UNITED STATES OF AMERICA
FOOD AND DRUG ADMINISTRATION
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CIRCULATORY SYSTEM DEVICES PANEL
OF THE MEDICAL DEVICES ADVISORY COMMITTEE
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PMA DISCUSSION, RECOMMENDATIONS,
AND VOTING
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WEDNESDAY,
JULY 28, 2004
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The
above-entitled Advisory Panel Meeting convened in the Grand Ballroom of the
Holiday Inn, Two Montgomery Village Avenue, Gaithersburg, Maryland, pursuant to
notice, at 9:00 a.m., Warren K. Laskey, M.D., Acting Chairperson, presiding.
PANEL MEMBERS PRESENT:
WARREN K. LASKEY, M.D., Acting Chairperson,
Uniformed
Services
University of Health Sciences
MITCHELL KRUCOFF, M.D., Voting Member, Duke
University
Medical
Center
WILLIAM H. MAISEL, M.D., M.P.H., Voting Member,
Brigham
& Women's Hospital
SHARON-LISE T. NORMAND, Ph.D., Voting Member,
Harvard
School
of Public Health
JEFFREY A. BRINKER, M.D., Consultant, Johns
Hopkins
Hospital
NORMAN S. KATO, M.D., Consultant, Cardiac Care
Medical
Group
JOHN C. SOMBERG, M.D., Consultant, American
Institute of Therapeutics
PANEL MEMBERS PRESENT: (cont'd)
ALBERT L. WALDO, M.D. (via telephone),
Consultant,
University Hospitals of Cleveland
CLYDE YANCY, M.D., University of Texas
Southwestern
Medical
Center
MICHAEL MORTON, Industry Representative, Cardiac
Surgery,
North America Sorin Group
CHRISTINE MOORE, Consumer Representative
GERETTA WOOD, Executive Secretary
BRAM ZUCKERMAN, Division Director, FDA
PRESENTERS:
Sponsor Presentation - Guidant Panel Attendees:
JOHN P. BOEHMER, M.D.
MICHAEL R. BRISTOW, M.D., Ph.D.
PETER E. CARSON, M.D.
DAVID L. DeMETS, Ph.D.
ARTHUR M. FELDMAN, M.D.
LESLIE A. SAXON, M.D.
U.S. Food and Drug Administration Presentation:
OWEN P. FARIS, Ph.D.
BARBARA KRASNICKA, Ph.D.
SCOTT PROESTEL, M.D.
A-G-E-N-D-A
PAGE
I. Call to
Order 3
II. Open
Public Session 10
III. Sponsor
Presentation: Guidant 12
Corporation
IV. Questions
and Answers 82
V. FDA
Presentation 109
VI. Questions
and Answers 136
ADJOURN
- BREAK FOR LUNCH 158
VII. Call
to Order 159
VIII. Open
Committee Discussion 160
IX. Open
Public Session 304
P-R-O-C-E-E-D-I-N-G-S
(9:01
a.m.)
ACTING
CHAIR LASKEY: Well, good morning. It being 9:00, I'd like to call us to order.
This
morning we meet discussing the pre-market application for the Guidant Cardiac
Resynchronization Therapy Defibrillators, P010012, Supplement 26.
And
we'll begin as usual with Ms. Wood reading the conflict of interest statement.
MS.
WOOD: The following announcement
addresses conflict of interest issues associated with this meeting and is made
a part of the record to preclude even the appearance of an impropriety. To determine if any conflict existed, the
agency reviewed the submitted agenda and all financial interests reported by
the committee participants.
The
conflict of interest statutes prohibit special government employees from
participating in matters that could affect their or their employers' financial
interests. However, the agency has
determined that participation of certain members and consultants, the need for
whose services outweighs the potential conflict of interest involved, is in the
best interest of the government.
Therefore,
waivers have been granted for Drs. Jeffrey Brinker, Mitchell Krucoff, William
Maisel, John Somberg, and Albert Waldo, for their interests in firms that could
potentially be affected by the panel's recommendations.
The
waivers for Drs. Brinker, Krucoff, Maisel, Somberg, and Waldo involve a grant
to their institution for the sponsor study.
The panelists had no knowledge of the funding and had no involvement in
data generation or analysis. Dr.
Krucoff's waiver also involves consulting for the sponsor on unrelated matters
for which he receives an annual fee of less than $10,001, and consulting with a
firm that has a financial interest in a competitor or unrelated matters for
which he receives an annual fee of less than $10,001.
The
waivers allow these individuals to participate fully in today's
deliberations. Copies of these waivers
may be obtained from the agency's Freedom of Information Office, Room 12A-15 of
the Parklawn Building.
We
would like to note for the record that the agency took into consideration other
matters regarding Drs. Brinker, Krucoff, and Dr. Clyde Yancy. These panelists reported past or current
interest involving firms at issue but in matters that are not related to
today's agenda.
The
agency has determined, therefore, that these individuals may participate fully
in the panel's deliberations. The
agency also would like to note that Dr. Warren Laskey has consented to serve as
chair for the duration of this meeting.
In the event that the discussions involve any other products or firms
not already on the agenda for which an FDA participant has a financial
interest, the participant should excuse him or herself from such involvement,
and the exclusion will be noted for the record.
With
respect to all other participants, we ask in the interest of fairness that all
persons making statements or presentations disclose any current or previous
financial involvement with any firm whose products they may wish to comment
upon.
ACTING
CHAIR LASKEY: I'd like to have the
panel members introduce themselves, beginning on my right.
DR.
ZUCKERMAN: Dr. Waldo, can you hear us?
DR.
WALDO: Yes, I can.
DR.
ZUCKERMAN: Can you introduce yourself,
please?
DR.
WALDO: I'm Dr. Albert Waldo from Case
Western Reserve University.
DR.
ZUCKERMAN: Bram Zuckerman, Director,
FDA Division of Cardiovascular Devices.
DR.
KATO: Norman Kato, private practice,
Encino, California.
DR.
YANCY: Clyde Yancy, UT Southwestern,
Dallas.
DR.
MAISEL: William Maisel, Cardiovascular
Division, Brigham & Women's Hospital in Boston.
DR.
BRINKER: Jeff Brinker, Johns Hopkins.
DR.
NORMAND: Sharon-Lise Normand,
Statistician, Harvard Medical School and Harvard School of Public Health.
ACTING
CHAIR LASKEY: Warren Laskey. I'm an Interventional Cardiologist, the
Uniformed Services University.
MS.
WOOD: Geretta Wood, Executive
Secretary.
DR.
KRUCOFF: Mitch Krucoff, Cardiologist at
Duke. I'm Director of the
Cardiovascular Devices Unit at the Duke Clinical Research Institute.
DR.
SOMBERG: John Somberg, Rush University.
MS.
MOORE: Christine Moore, Consumer
Representative.
MR.
MORTON: Michael Morton. I'm the Industry Representative. I'm employed by Sorin Group.
ACTING
CHAIR LASKEY: Thank you.
And,
Geretta, could you please read the voting status statement.
MS.
WOOD: Pursuant to the authority granted
under the Medical Devices Advisory Committee charter, dated October 27, 1990,
and as amended August 18, 1999, I appoint the following individuals as
voting members of the Circulatory System Devices Panel for this meeting on July
28, 2004: Warren Laskey, M.D., serving
as Chairperson; Norman S. Kato, M.D.; Clyde Yancy, M.D.; John C. Somberg,
M.D.; Albert L. Waldo, M.D.; Jeffrey A.
Brinker, M.D.
For
the record, these individuals are special government employees and are
consultants to this panel under the Medical Devices Advisory Committee. They have undergone the customary conflict
of interest review and have reviewed the material to be considered at this
meeting.
This
is signed by Daniel G. Schultz, M.D., Director, Center for Devices and
Radiological Health, and dated July 23, 2004.
ACTING
CHAIR LASKEY: Thank you.
Before
we begin the open public hearing portion, I'd like to read the following
statement. Both the Food and Drug
Administration and the public believe in a transparent process for
information-gathering and decision-making.
To ensure such transparency at the open public hearing session of the
Advisory Committee meeting, FDA believes it is important to understand the
context of an individual's presentation.
For
this reason, FDA encourages you, the open public hearing speaker, at the
beginning of your written or oral statement to advise the committee of any
financial relationship that you may have with the sponsor, its product, and, if
known, its direct competitors. For
example, this financial information may include the sponsor's payment of your
travel, lodging, or other expenses in connection with your attendance at the
meeting.
Likewise,
FDA encourages you at the beginning of your statement to advise the committee
if you do not have any such financial relationships. If you choose not to address this issue of financial
relationships at the beginning of your statement, it will not preclude you from
speaking.
That
being said, I'd like to ask the audience if there's anyone who wishes to
address the panel on today's topic, or any other topic. If not, then I'm delighted to close the open
public hearing portion and proceed with the sponsor's presentation.
DR.
WALDO: Excuse me. This is Al Waldo. It's very, very hard for me to hear you.
DR.
ZUCKERMAN: Okay.
DR.
WALDO: I can hear you. Is that you, Bram?
DR.
ZUCKERMAN: Yes.
DR.
WALDO: I can hear you very well, but
anyone distant from the mike is very hard for me to hear.
DR.
SOMBERG: You have to put the telephone
receiver near where the speaker is.
DR.
ZUCKERMAN: Okay.
DR.
SOMBERG: It's not going to work near
the microphone. It's ‑‑
DR.
ZUCKERMAN: Yes. We're about to get a better telephone. Let me check on that.
(Pause.)
MS.
WOOD: We would just like to remind the
sponsor to please introduce yourself and state your connection with the company
and any conflict of interest that you might have.
(Pause.)
Go
ahead and get set up, but we'll try to wait just a minute to make sure we can
patch Dr. Waldo in where he can hear your presentation.
(Pause.)
ACTING
CHAIR LASKEY: Please forgive the
appearance of chaos up here. If you
would, proceed.
DR.
FELDMAN: Thank you.
Good
morning. I'm Arthur Feldman from
Jefferson Medical College in Philadelphia, and I'm very pleased to be able to
be here this morning to be one of the panel that will be presenting to you data
this morning from the COMPANION trial.
My
conflict of interests include the fact that I'm a consultant for numerous
companies, both in general cardiology and in the heart failure arena, including
I received travel expenses and room and board to come here today, as well as a
modest honorarium.
I
was an investigator for the COMPANION trial, and I served as the co-chairman of
that trial.
I'd
like to begin by introducing to you the members of the trial that are here
today and will be presenting to you first.
First is Dr. John Boehmer who is an Associate Professor of Medicine and
Surgery at the Penn State College of Medicine; Dr. Michael Bristow, who is the
Gilbert Blout Professor of Medicine and co-Director of the Cardiovascular
Institute at the University of Colorado; Dr. Peter Carson, who chaired the
Morbidity and Mortality Committee and is Associate Professor of Medicine at
Georgetown. Dr. Bristow is also the
co-chair of the Steering Committee.
Dr.
David DeMets, who directed the Statistical Data Analysis Center for this trial
and is professor and chair of the Department of Biostatistics and Medical
Informatics at the University of Wisconsin; Dr. Leslie Saxon, a member of the
Steering Committee, who is Professor of Medicine and Director of Cardiac
Physiology ‑‑ or Electrophysiology, excuse me, at the University of
Southern California; and Dr. Jonathan Steinberg who is a member of the
Morbidity and Mortality Committee and is Chief of the Division of Cardiology at
Roosevelt/St. Luke's Hospital in New York.
This
morning, the agenda as seen before you here, I'm going to start by reviewing
some of the background for the COMPANION trial and for giving you a study
overview of the COMPANION trial.
Dr.
Peter Carson will then speak to data handling from the trial and the
adjudication process. Dr. Michael
Bristow will present the effectiveness results. Dr. David DeMets will present the statistical
considerations. And then, Dr. Saxon
will present the safety data and will summarize the study conclusions on behalf
of the Steering Committee.
I'd
like to first just preface my remarks with a little bit of the regulatory
history for this trial. You can see
here that the pre-IDE meeting was held in June of 1999. The FDA sent an agreement letter in
September of '99, and the first patient was enrolled in this trial in January
of 2000. The study was stopped on the
recommendation of the Data and Safety Monitoring Committee on 11/18/02, and
subsequent notices were filed with the FDA.
This
next slide just makes the point that there were numerous and extensive
interactions between the sponsor and the FDA during the course of this
trial. These include reviewers' memos,
which are found in your packets, and also systems safety communications with
the approval of CONTAK CD and EASYTRAK lead systems; in May of '02, the renewal
TR approval based on CONTAK TR substudy data in 104.
Next
slide.
Now,
I think many of you are aware of the background to this study, but I think it's
worthwhile to review it in brief. I
think this panel is certainly aware of the fact that heart failure is a disease
of epidemic proportions in the United States affecting nearly six million
people, that it's a progressive disease, and that it's characterized by very
high morbidity and mortality.
Over
the past two decades, a number of pharmacologic therapies have been evaluated
and have proven salutory in both prolonging survival and improving outcomes in
patients with this disease. However, it
has been recognized now for over a decade that approximately 30 percent of
patients with heart failure have a prolongation in conduction that results in a
dysynchrony in cardiac contractility, and it further impairs myocardial
function as well as adversely affecting the biology of the already-failing
myocardium. And, unfortunately,
pharmacologic agents do not address this pathophysiologic problem.
Resynchronization
through electrical stimulation of both ventricles, or cardiac resynchronization
therapy, has been shown to improve myocardial function, reverse ventricular
remodeling, and actually improve the biology of the failing heart.
Next
slide.
So
how does CRT therapy work? Well, this
is a diagrammatic drawing. You can see
a blockage right here in the conduction system, and CRT therapy works by simply
placing electrodes on the surface of the heart and then having these both ‑‑
having these timed appropriately to synchronize the contraction of the two
ventricles.
Initially,
about eight to nine years ago, these pacemakers were placed, or these leads
were placed, on the surface of the heart using an approach through a
thoracotomy. This was found to be
beneficial in terms of improving cardiac hemodynamics. However, obviously, the morbidity associated
with a thoracotomy was somewhat problematic in this group of patients.
More
recently, leads have been developed which were used in this study, which
allowed a totally percutaneous implantation by placing a lead through the
coronary sinus, then down the great coronary vein, and approaching the surface
of the left ventricle, with the right ventricular lead being placed consistent
with standard lead placements for pacemaker devices.
Next
slide.
We'll
use some new terminology in the presentation that has come into the world of
heart failure over the past few years.
This includes CRT or cardiac resynchronization therapy. This is a generic term that describes the
therapy independent of the device; CRT-P, which describes a device with
biventricular pacing capabilities alone; and then, CRT-D, which describes a
device with both biventricular pacing and defibrillation capabilities.
Now,
we had a number of rationales for the COMPANION trial. The first was that CRT-P or CRT-D devices
have the potential, because of their effects on remodeling, to reduce mortality
in a heart failure hospitalization's in-patients with advanced heart failure.
Now,
at the time that COMPANION was started ‑‑ in fact, up 'til today ‑‑
there have been no appropriately powered clinical trials that were designed on
an intention-to-treat basis that have prospectively investigated the effect of
CRT on mortality or on hospitalizations.
Now,
this was important because it was really these two endpoints which were keys to
understanding the efficacy of this treatment and the importance of this
treatment for the heart failure population, and specifically for the heart
failure physician.
Next
slide.
So
the COMPANION trial was designed to determine if CRT-P or CRT-D resulted in a
significant reduction of a composite of time to first all-cause hospitalization
or all-cause mortality when compared with optimal pharmacologic therapy
alone. Combined endpoints incorporating
both mortality and hospitalization are a standard for primary endpoints to
receive a robust heart failure clinical trial endpoint.
The
motivation behind this composite endpoint was the desire to address both
mortality and morbidity. Incorporating
all-cause hospitalization into a composite endpoint helps to address the
challenge of competing risk and raises the bar for demonstrating effectiveness
of CRT when compared to other heart failure trials.
This
is the study design of the COMPANION trial.
You can see that after enrollment patients underwent baseline
testing. They were then randomized to
one of three arms ‑‑ either to optimal pharmacologic therapy or
OPT, OPT plus CRT-P, and OPT plus CRT-D.
The
randomization was one to two to two, and I make this point so that you will
recognize during later presentations the fact that there were twice as many
patients in the OPT/CRT-D group as in the OPT group.
Another
important feature of this trial was that the clock started ticking at the time
of randomization. So, in other words,
if an event occurred between randomization and device implant in any of these
patients, that was considered as an endpoint for the trial, despite the fact
that the device had not yet been implanted.
So this was a very conservative approach to analysis of the trial.
A
two-day window was set for implantation.
The randomization was stratified, both by site and by beta blocker
therapy, and the hospitalizations associated with the investigational device ‑‑
in other words, hospitalizations to implant a device ‑‑ were not
considered as a study endpoint, because obviously if they were then each
patient, at the time of randomization, would actually be a study endpoint.
Next
slide.
I
would point out also that we will concentrate today ‑‑ we will
focus exclusively today ‑‑ on this OPT and CRT-D group and its
comparison with OPT alone. And the
reason for that was that the OPT and CRT-P data was previously supplied to the
agency and was used in the approval for this device.
Now,
the indications currently for a CRT-D device are seen here. They include New York Heart Association
Class III or IV symptoms despite optimal pharmacologic therapy, a QRS greater
than or equal to 120 milliseconds, an ejection fraction less than or equal to
35 percent, and an indication for conventional ICD.
We
are proposing, based on the data that you'll see today, that these indications
should be expanded to now include the same patient population ‑‑
that is, symptomatic patients with QRSs greater than or equal to 120
milliseconds and an ejection fraction of less than or equal to 35 percent, but
also a current ICD indication or COMPANION patient population criteria.
Now,
the composite primary endpoint for this trial was the composite of time to
first all-cause hospitalization or all-cause mortality event. This composite endpoint included mortality
to account for mortality as a competing risk.
It was analyzed as time to first event as measured, again, from the
randomization visit, not from the implantation.
The
analysis was intentioned to treat from the time of randomization, and per
agreement with the FDA, and in order to preserve hospitalization as a valid,
morbidity clinical endpoint, the investigational device implant was not
considered to be a hospitalization event.
Next
slide.
So
the primary endpoint consisted of a composite of death from any cause and
hospitalization for any cause. However,
it also included IV inotrophs or vasoactive drugs being administered for four
hours in an outpatient hospital or physician office, because this was viewed as
an instance of the primary endpoint with respect to hospitalization.
Now,
secondary endpoints for the trial included all-cause mortality with the highest
order secondary endpoint being all-cause mortality, and this was analyzed by
intention to treat and it was analyzed as time to event as measured from the
randomization visit, and cardiac morbidity also analyzed by intention to treat.
This
slide shows the main entry criteria for the COMPANION trial. It included New York Heart Association Class
III or IV symptoms, optimal pharmacologic therapy which was defined as loop
diuretics, beta blockers, ACE inhibitors, and spironolactone.
Patients
could be enrolled if they were found to be intolerant of these agents. However, if they were on a beta blocker or
an ACE inhibitor, it needed to be at a stable dose for greater than three
months in the case of beta blockers, and for greater than one month in the case
of ACE inhibitors. Spironolactone also
had to be at a stable dose for greater than one month.
The
ejection fraction had to be less than or equal to 35 percent with a left
ventricular end diastolic dimension of greater than or equal to 60
millimeters. And the QRS had to be
greater than or equal to 120 milliseconds with a PR interval of greater than
150 milliseconds.
Each
patient was required to have had a heart failure hospitalization between one
and 12 months prior to enrollment, and there could be no indication for either
a pacemaker or for an ICD.
This,
again, shows the study design. Again,
I'd point out that after randomization patients were randomized to one of three
arms. I think it's important to also
note that the patients who received the device had a hospitalization or a visit
with both the physicians and the study nurse at this point, and then
subsequently all patients were seen at one week, one month, and then every
three months.
We
made a number of statistical assumptions in establishing the goals for this
trial. The trial was powered to detect
a 25 percent relative reduction in 12-month event rates in each device arm
versus optimal pharmacologic therapy for both the primary and the secondary
all-cause mortality endpoints.
Alpha
allocation was set at 0.02 for CRT-P versus OPT and at 0.03 for CRT-D versus
OPT. This shows you down in the bottom
part ‑‑ portion of the slide the assumed event rate for mortality
or hospitalization in the control group and in terms ‑‑ and
mortality endpoint in the control group, this being 24 percent mortality and 40
percent event rate for mortality or hospitalization.
This
was the expected absolute reduction or the assumed absolute reduction ‑‑
10 percent in mortality or hospitalizations, and six percent in mortality ‑‑
to give a power of greater than 90 percent for the primary endpoint and 80
percent for the mortality endpoint.
This
was an event-driven trial with a target number of 1,000 first events to be
detected for a 25 percent reduction for the primary endpoint. There was sequential monitoring of both the
primary and the secondary all-cause mortality endpoint events performed by the
DSMB every six months during the course of the trial.
Now,
the management of the trial is seen on this slide, and it was independent of
the sponsors. The Steering Committee
was charged with providing overall guidance and leadership of the study. The Morbidity and Mortality Committee
developed a process and the precise operational criteria for adjudication of
the study endpoints, and then reviewed and adjudicated deaths and
hospitalizations.
The
Data and Safety Monitoring Board reviewed study outcomes, including safety at
prescribed intervals. The independent
statistical group provided statistical support as well as guidance, and the
contract research organization administrated the study and acted as a
clearinghouse for CRFs and study monitoring.
This shows the relationships between the
various entities that were part of this study.
You can see that the contract research organization received information
from the independent statistical group.
It gave data from patient centers to the Morbidity and Mortality
Committee for their adjudication. It
interacted with the sponsor.
The
independent statistical group provided information to the Data and Safety
Monitoring Board, who in turn made recommendations to the Steering
Committee. And there was also
interaction between the sponsor and the Steering Committee, and the sponsor
communicated with the Food and Drug Administration.
During
the context of this study, there were three occasions or approximately three
occasions when there was direct interaction between components of the study
outside of this diagram. First, the
Morbidity and Mortality Committee communicated with the Steering Committee to
clarify hospitalization as a calendar date change.
Second,
the Data and Safety Monitoring Board communicated with the Food and Drug
Administration regarding instances of coronary venous trauma and to provide
information about changes that were made in the protocol for administration of
these devices as a result of this finding.
And
then, finally, the independent statistical group interacted with the Steering
Committee in recommending gathering of post-withdrawal data.
Next
slide.
I'd
like to now turn the podium over to Dr. Peter Carson, who will discuss data
handling and the adjudication process.
DR. CARSON: Thank you, Dr. Feldman.
I'm
Peter Carson, and I am speaking to you this morning as the Chairman of the
Morbidity and Mortality Committee of COMPANION. My conflicts are as chairman of that committee and also as a
member of the panel for Guidant today.
I have no other relationship to the sponsor.
The
slide that is up at this point is looking at the data flow process from the
standpoint of the Morbidity and Mortality Committee. A patient event that occurred would be reported on a clinical report
form to the CRO, and all hospitalizations, four-hour inotrope use as an
outpatient and deaths would then be assembled as a dossier and sent to the
Morbidity and Mortality Committee to adjudicate.
The
Morbidity and Mortality Committee then would meet in a process that I'll
describe a little more later, adjudicate these events, communicate them back to
the CRO, which would then further communicate them to the statistical group. There would be a final report that would
then go to the sponsor.
The
Morbidity and Mortality Committee communicated only with the CRO and with the
Steering Committee. The Steering
Committee communication was through me, and I was an ex officio member of the
Steering Committee. And I would
emphasize that the M&M Committee had no contact with the sponsor through
the course of the trial.
Next
slide.
The
Morbidity and Mortality Committee was composed of seven cardiologists, and I
want to take special mention of them.
This was a remarkable group, and I feel like I'm a position to say so as
I have chaired or been a member of virtually every Endpoint Committee in heart
failure over the last 12 years. This
group had great expertise in heart failure, clinical trials, regulatory
experience, and also electrophysiology.
And
it is well that this group had this expertise ‑‑ if we could go to
the next slide ‑‑ because the committee performed a number of
functions, developed the process and precise operational criteria for
adjudication of study endpoints. We
reviewed and adjudicated deaths and hospitalizations. For those deaths, we defined and adjudicated a mode of death, and
we also adjudicated the relationship of death to device implant.
Regarding
hospitalization, further, we defined and adjudicated specific causes of
hospitalization. And, finally, we
adjudicated cardiac morbidity.
Next
slide.
In
consideration of ‑‑ regarding operational definitions, some of the
committee's criteria involved these thoughts.
For a hospitalization event, an event should be of sufficient morbidity
to enter a composite with mortality, and should also have verifiable
components.
For
cause-specific mortality, we assessed that the cause of death would be the
event that defined the patient's clinical course or altered it, and it should
be definitions that have been used in previous clinical trials.
For
cause-specific hospitalizations, similarly, we wanted to indicate the primary
reason for hospitalization. With
evidence from specific treatment and response, we again wanted definitions that
had been used in other clinical trials.
I should note that, per protocol, we did not adjudicate elective
implants or reimplant hospitalizations.
Next
slide.
For
mode of death analysis, as said, the primary mode of death related to the event
that led to death. We did not usually
adjudicate according to the terminal event.
We
principally assessed cardiac deaths, because that's what occurred in
COMPANION. The two principal causes are
sudden, unexpected, and pump failure, and you see short descriptions of these
modes of death on this slide. As with
other parameters on this slide, fuller definitions are in the Morbidity and
Mortality Committee manual.
Other
causes, as you see, for cardiac deaths include ischemic deaths in two ways ‑‑
cardiac procedure, other cardiac.
Vascular deaths, non-cardiac deaths.
And for those cases in which there was simply no data available, these
cases would be assessed as unknown or unclassifiable.
In
terms of the relation of device implant to mortality, we used a schema that was
typical of intervention trials ‑‑ pre-operative, after
randomization but before implant; peri-operative, within 30 days;
post-operative, after 30 days. We
assessed the relationship as non-applicable if this was a patient in the OPT
arm or a CRT-D patient who never received a device. Procedure-related and device-related were also assessed, and
these details are once again in the operations manual of the committee.
For
hospitalizations, let me principally say a word about heart failure
hospitalizations. We were looking for a
principal diagnosis of heart failure.
We looked for increases signs or symptoms of heart failure. And treatment had to include intravenous
therapy, either diuretic or another type of vasoactive drug, or it could be
other parenteral therapy on occasion, or we also assessed its significant
alteration in oral therapy could also be included in the diagnosis of a heart
failure hospitalization.
We
adjudicated many other causes of cardiac hospitalization. I should also add that we also adjudicated
all non-cardiac hospitalizations also, and that is quite unique for any heart
failure trial.
The
cardiac morbidity index is seen on this slide.
This is from the protocol.
Please recall that hospitalization was assessed as the primary reason
when we looked at it, and, therefore, one of the purposes of the cardiac
morbidity scale was to pick up other morbidities that might have happened
during the hospitalization or other important components of that initial reason
for hospitalization.
Bear
in mind that all of these aspects of cardiac morbidity would be reflecting
cardiac worsening. That was their
design, and that was the way the committee adjudicated them.
Next
slide.
The
M&M Committee adjudication process involved the CRO collating clinical
summary and event information from investigational centers. This was to involve hospitalizations. It involved a calendar date change, and I'll
show you the hospitalization CRF for that later. Also, outpatient IV or vasoactive drug use for greater than four
hours on another CRF, and, of course, all deaths.
Please
note the committee did not screen adverse experiences. All AEs in submission were reported by
center, reviewed by the CRO, and submitted to the Data and Safety Monitoring
Board in a summary format.
A
little further detail on the adjudication process in terms of what we received
from the CRO, and I should point out that the documentation in the COMPANION
trial was among the best I've seen in any clinical trial I've been associated
with.
This
involved hospitalization data, admission summary and physical, discharge
summary, lab reports, progress notes when we needed them. Death data included a physician narrative,
clinic notes, and a discharge summary if the patient had had a recent previous
hospitalization.
A
primary and secondary reviewer were assigned to each event, and they reviewed,
presented the cases to the committee, and a vote was taken for each
adjudication. It should be pointed out
that the patient ID, randomization arm, physician center, etcetera, were all
removed from the documentation that both reviewers and the committee saw. The process for each committee meeting was
documented with meeting minutes.
I
should make a statement about M&M Committee blinding. I think as you probably all realize, in a
device trial such as COMPANION, blinding is largely problematic. For mortality events, the committee
adjudicated the relation of device and implant procedure to death, so,
therefore, the committee had to be unblinded to whether the patient had a
device or not.
For
hospitalization events, while, as I said, all identifying data was removed to
the degree possible, the nature of a hospitalization or the events themselves
or statements in the narrative, even if you black them out, might reveal or
hint the presence of a device.
However,
please keep in mind that the committee functions in equipoise regarding the
study hypothesis, and, therefore, the knowledge of the treatment arm should not
interfere or influence adjudication of individual events. And the committee at no time had knowledge
of cumulative events or assembled data.
Further,
while CRO members were present at committee meetings, no sponsor representative
was ever present, and all communication was to the CRO or to the Steering
Committee.
Next
slide.
Now,
there has been concern about the definition of hospitalization adjudication,
and just a few comments to make here.
The committee believed that the protocol intended that an event be
significantly or sufficiently morbid to enter into a composite endpoint with
death.
It
is also true that all trials prior to COMPANION had used a parameter of a
24-hour duration hospitalization. For
these reasons, the committee initially used a 24-hour duration as the
descriptor of an all-cause hospitalization.
Now,
the largest experience in this area prior to COMPANION was MERIT heart failure
and VALHeFT. In both of those trials,
the committees ultimately used a descriptor of a calendar date change, and they
did so for the same reasons as we did, which is that early in the adjudication
process it became apparent that discharge times were not uniformly available.
Therefore,
the committee agreed to adopt what was a more verifiable and precise approach
of a calendar date change. This
operational criteria was approved by the Steering Committee and utilized for
all hospitalizations and included in all analyses.
There
were 113 hospitalizations adjudicated prior to the adoption of this
criteria. All were reviewed, none
changed. If you look on the next slide,
you see two things that are quite important.
One is the flow of events through the course of the trial, noting that
the first Endpoint Committee meeting was 3/16/01, and that on 1/19/01, after
113 events, we particularly used to use ‑‑ we used a calendar date
change.
Then,
for a hospitalization, this is the overall stream of events that occurred
through the course of the trial. This
is why I particularly compliment this committee. I should also say that the hospitalization CRF was in place at
the start of the trial, and it was the same hospitalization CRF for the entire
trial.
If
you go to the next slide, this is the hospitalization CRF. What this hospitalization CRF asked the site
to report was what day the patient was admitted and what day the patient was
discharged. It did not ask for
times. The committee did realize during
the course of adjudicating that first 113 events that we could not accurately
ascertain always the discharge summary.
We
felt we would be vulnerable to the issue of the times, and, therefore, we felt
this was clearly verifiable. Note that
this form was in place at the very beginning of the trial.
Next
slide.
In
terms of ‑‑ Dr. Feldman talked to you about four-hour inotrope or
vasoactive therapy use. We used this
definition for the adjudication of these events. This is actually the wording of the definition that is out of the
cardiac morbidity area of the protocol.
I
should comment that four-hour endpoint of IV inotrope or vasoactive therapy use
has really been the only way that this endpoint has ever been used in clinical
trials, and it provides assurance that the administration of IV therapy is
clinically meaningful and is a hospitalization equivalent.
Next
slide.
And
just like with the hospitalization CRF, this was the CRF that the sites always
used that had the four-hour distinction for IV vasoactive or inotrope use. So this was also used from the beginning of
the trial onward.
Next
slide.
Let
me conclude by saying that the COMPANION Endpoint Committee provided
operational criteria for events occurring during the study. The classifications used were those used in
previous clinical trials. They provided
verifiable data and maximized capture of significant events.
The
adjudication process consisted of activities that are the standard practice for
clinical trials in heart failure.
Thank
you.
ACTING
CHAIR LASKEY: Thank you.
Dr.
Bristow, if you would kindly indulge us for a moment, we're going to try and
get Dr. Waldo back online. So can we
just take a minute?
I
was just told it wasn't going to take a while, so either we move ahead or ‑‑
five-minute break? Mike, is that all
right?
DR.
BRISTOW: Sure.
ACTING
CHAIR LASKEY: All right. Five-minute break, please, and we'll ‑‑
we will regroup.
Thank
you.
(Whereupon, the
proceedings in the foregoing matter went off the record at 9:44 a.m. and went
back on the record at 10:00 a.m.)
ACTING
CHAIR LASKEY: Thank you for your
indulgence. I guess we're functional,
as we say. So we'll continue with Dr.
Bristow's presentation.
DR.
BRISTOW: Thank you, Dr. Laskey.
It's
my privilege to present the effectiveness results of COMPANION. I'm Mike Bristow from the University of
Colorado. I was a co-chairman of the
Steering Committee. My other relevant
conflicts are that I'm a consultant to Guidant, and I also receive research
support to Guidant.
MS.
WOOD: Sir, pull the mike up just a
little.
DR.
BRISTOW: The first slide is the
geographic location of the study centers.
This was entirely a U.S. study conducted in 120 U.S. centers averaging
12 patients enrolled per center. This
gives some of the baseline demographics and other historical data in the two
treatment groups.
The
first point in the baseline data is that none of these parameters that we're
going to be describing are different between the two treatment groups. So the age is late sixties, which is a
little older than standard heart failure clinical trials that have reported
lately.
We
had a substantial number of women, a little higher than most heart failure
clinical trials, so 67, 69 percent male.
And the New York Heart Class ‑‑ all Class III and IV. This was an advanced heart failure study.
Duration
of heart failure is typical for a heart failure ‑‑ chronic heart
failure clinical trial, three to four years.
Severe LD dysfunction, average EF, 22 percent. Dilated chrome EPI phenotype, as mandated in the protocol, was
6.7 centimeter ventricles.
Heart
rate a little lower than is usually seen in heart failure clinical trials,
reflecting a background therapy of beta block aid ‑‑ one of the
lowest, if not the lowest, systolic blood pressure at a heart failure clinical
trial reporting at least oral agents ‑‑ in this case, obviously, a
device trial at 112.
Next
slide.
Moderate
exercise, six-minute walk, on the high side PR intervals and QRS durations
based on the protocol, 55 to 60 percent ischemic typical for a heart failure
trial enriched in diabetes, also typical for a heart failure trial, 45 percent. Seventy percent left bundle.
Background
therapy shown here ‑‑ approximately 90 percent of patients on an
ACE or an ARB, 66 or 68 percent on a beta blocker, virtually all patients on a
loop diuretic, and 55 percent on spironolactone, probably representing the
upper limit of tolerability of this agent in an advanced heart failure
population.
This
slide gives some of the details on trial termination. On November 18, 2002, the DSMB recommended to the Steering
Committee that enrollment be stopped for two reasons. First and foremost, this was an event-driven trial with a target
number of events of 1,000, and it was the opinion of the DSMB at that time that
that target had been reached, based on the number of endpoints that they were
reviewing at that time ‑‑ 941.
And
then, projecting the number of endpoints that had not yet come in ‑‑
and, in fact, the final number of endpoints analyzed in COMPANION was
1,020. The second point was that the
effectiveness boundaries for the primary endpoint and mortality had been
crossed in the CRT-D group at that time.
So
the Steering Committee followed this recommendation, stopped enrollment at
1,520 randomized patients on that date, and established a study cutoff date for
gathering efficacy date as November 30, 2002.
These
are the sequential monitoring Z values that the DSMB was observing over
time, and you can see out here at the end of the trial the boundary for the
primary endpoint being crossed.
These
are the Kaplan-Meier curves for the primary endpoint, which is a composite of
time to mortality or all-cause hospitalization. And the OPT or control group is in red. The interrupted line and the solid blue line is CRT-D.
The
first point is that the 12-month event rate in the OPT group was 68 percent,
which is somewhat higher than we had projected. In the CRT-D group, the 12-month event rate was reduced to 56
percent. That's a 12 percent absolute
reduction.
The
hazard ratio for these two curves is .80, statistically significant, relative
risk reduction of 20 percent.
Therefore, a P value adjusted for sequential monitoring ending up being
.011, which is under the critical value of .03.
Now,
in terms of the components of this primary endpoint, if ‑‑ taking
both groups together, 90 percent of the primary endpoints were
hospitalization. Seven and a half
percent were mortality, approximately.
And only two and a half percent were the IV inotrope use.
Next
slide.
This
adds on to the Kaplan-Meier curve the results in the CRT-P group for the
primary endpoint. And you can see that
the CRT-P group actually is virtually superimposable to the CRT-D group. In other words, the treatment effect for the
primary endpoint heavily driven by hospitalization, is virtually identical in
the CRT-D and CRT-P group.
Next
slide.
These
are some subgroup analyses, hazard ratios for standard subgroups that are
looked at for the ‑‑ in heart failure trials for the primary
endpoint, and the important point is that all of these point estimates lie to
the left of unity, indicating homogeneity, essentially, of treatment effect for
the primary endpoint.
Next
slide.
This
is the sequential monitoring data for the Z statistic that DSMB was following
for all-cause mortality. And you can
see the boundary effectiveness, boundary being crossed here at the end of the
trial for mortality.
These
are the Kaplan-Meier curves for the secondary endpoint of all-cause
mortality. Obviously, these curves are
very different. The 12-month event rate
in the OPT group was 19 percent ‑‑ a little less than predicted ‑‑
down to 12 percent in the CRT-D group, absolute risk reduction of seven
percent. The hazard ratio for these
curves is .64. That's a 36 percent
relative risk reduction, highly statistically significant P value.
Next
slide.
This
adds on the mortality results for the CRT-P group. And unlike for the primary endpoint, these curves are somewhat
different. So this is CRT‑P,
which has a hazard ratio of .76 compared to the .64 for CRT-D. And so two-thirds of the reduction in
mortality in this trial was achieved in the CRT-P group compared to the CRT-D
group.
Next
slide.
This
gives some of the subgroup analysis data for all-cause mortality. And much like the primary endpoint, the vast
majority of these point estimates lie to the left of unity, indicating
homogeneity of treatment effect across subgroups.
Next
slide.
This
is some of the death classification data from Dr. Carson's Morbidity and
Mortality Committee. The majority of
deaths in this study, as you would imagine, are cardiac ‑‑ around
three-fourths. So here is the crude
mortality rate in the OPT arm versus CRT-D, 18.8 versus 12.8 percent,
statistically significant.
Here
is the subdivision by the two major types of cardiac death ‑‑
adjudicated pump failure and sudden death.
There are either trends or statistically significant reductions in both
of these modes of death, with a greater degree of reduction perhaps, for sudden
death. And here are the other more
minor modes of death that were classified.
Next
slide.
So
this slide gives the projected event rates and treatment results based on what
actually happened. So as we've already
said, we projected that the primary endpoint event rate would be 40 percent at
12 months, and 24 percent for the secondary endpoint ‑‑ the event
rate at 12 months, the actual ‑‑ in the OPT group.
The
actual event rates achieved are shown here ‑‑ 68 percent, greater
obviously, for OPT for primary endpoint, and a little bit less for all-cause
mortality. So going down here to the
relative reductions, we assumed that we would get 25 percent relative risk
reduction, and we ‑‑ for the primary endpoint, and we ended up with
20.
We
assumed 25 percent for mortality, ended up with 36. What really counts for statistical significance is a combination
of the event rate and the absolute risk reduction. And in the case of the primary endpoint and mortality, the
absolute risk reduction was a little greater than we anticipated ‑‑
10 versus 12 for the primary endpoint, six versus seven for all-cause mortality.
We
measured cardiac morbidity by protocol in this trial. So there was a cardiac morbidity index designed to encompass all
significant events that could happen to a heart failure patient ‑‑
significant clinical events, including in this case serious device-related
hospitalizations.
Now,
there is no standard definition for cardiac morbidity for advanced heart
failure trials. You can't reach into
the bucket and pull out a standard definition for this. So the protocol defined cardiac morbidity for
the COMPANION trial, and this endpoint was intended to measure frequency and
duration of all cardiac morbid events as defined in the protocol.
So
these are data for the aggregate of the cardiac morbidity index, in terms of
frequency per patient, frequency per patient per year, and duration. OPT is in red, and CRT-D is in blue. And you can see there's a reduction in these
morbidity measurements in the CRT-D group for all three of these types of
measures.
And
this breaks it out by component of the morbidity index. And for the ‑‑ at least for the
high prevalence components of this index, there is a reduction in the CRT-D
group. For example, hospitalization for
a acute decompensation heart failure, you see the degree of reduction here. Statistically significant.
Next
slide.
COMPANION,
I'll have to say, after working in heart failure clinical trials for nearly 25
years, was a bit of a challenging study to conduct, and for that matter to
design. The first sort of hurdle that
had to be overcome, as we knew that we were not going to be successful with
every implant, but we also wanted to conduct this as intention to treat with
randomization triggering essentially the tabulation of endpoints. We didn't want to wait for successful
implants and then start tabulating, which typically has been done in device
trials.
We
knew we had to drag along the upfront implant lack of success rate, and so in
the CRT-D group the success rate was 91 percent. So right up front, we're dragging along nine percent of patients
who did not get a device and could not have a treatment effect. So we have to overcome that with efficacy
over time.
Another
major challenge here that wasn't fully anticipated when the trial began,
because I don't believe it could have been, was that there were several devices
that were approved and, in fact, marketed while this trial was in progress ‑‑
several CRT devices. So a CRT-P device
was approved, a CRT-D device, and there were expanded indications for ICD based
on the beta trial, beta II trial, that came on the scene. And, of course, this created competition
essentially for enrollment.
And
so these challenges slowed enrollment and made maintaining patients in the
study somewhat of a challenge. So this
is enrollment by month over time in COMPANION, and you can see up until mid
2001 we're kind of zinging along here with increasing rates of enrollment. And then these devices started being
approved and marketed, and this is probably no coincidence ‑‑ that
our enrollment rate begins to drop.
Next
slide.
So
we had to have a response to that as a trial in terms of how to cope with this
and deal with this. So CRT device
approval while COMPANION was in progress clearly influenced investigator
equipoise. Investigators were faced
with the difficult choice of continuing to enroll and treat patients in
COMPANION or basically put a device in them in an open label fashion or drop
them into that therapy if they were COMPANION patients.
So
the Steering Committee strongly discouraged that and, through direct
communication with investigators, made them aware that the only way this could
happen in COMPANION ‑‑ that is, a patient could get an open label
drop-in device ‑‑ would be if they had progressive heart failure to
the point of having a heart failure hospitalization ‑‑ in other
words, would be endpointed first in COMPANION.
And
the investigators were required to consult with a Steering Committee member
prior to implanting device and produce on paper the evidence that this patient
had progressive heart failure.
Next
slide.
Nevertheless,
we did experience a disproportionate withdrawal rate in COMPANION in the OPT
group. And when this was first fully
appreciated, early 2003, the numbers were a withdrawal rate in the OPT group,
in-patients who had not previously had a primary endpoint of 13 percent, versus
two percent in the CRT-D group.
The
study, of course, was based on intention to treat, and due diligence in this
setting requires accounting for as many patients as possible. So Dr. DeMets, the independent statistician
in COMPANION, recommended to the Steering Committee to obtain vital status and
hospitalization status on all of the withdrawn patients.
In
order to do that and be in compliance with HIPAA regulations, we essentially
had to write a new protocol and reconsent patients that had withdrawn prior to
11/30/02, who had not had a primary endpoint.
Next
slide.
And
so we did that, and this was a very painful process requiring a total of seven
months, delaying publication of COMPANION and delaying this meeting today. So IRB-approved protocol had to occur in
each center. The patients had to sign a
written consent.
And,
therefore, data-gathering was just as it had been in patients who had not been
withdrawn. That is, case report forms
for the withdrawal contact were filled out, but ‑‑ which is in
addition to the standard, but also that the standard hospitalization, the CRFs
were filled out, and the data were handled and adjudicated just as other data
were thereafter.
Next
slide.
So here is what happened in terms of
withdrawals. So in terms of all
patients withdrawn, 26 percent in the OPT group versus 6.6 in the CRT ‑‑
now, these are final numbers, not the preliminary numbers I showed you
earlier. So in terms of patients who
had not had a primary endpoint, which is the important issue, 14 percent in OPT
versus 1.5 percent in CRT-D. This is
prior to the reconsent process.
And
so then we go through the reconsent. We
end up finding these extra endpoints, identifying these extra endpoints, 14 in
the OPT group, or 4.5 percent of the total, and .7 percent CRT-D. And then the real issue is: what are you left with at the end of all
this?
These
are the number of patients with no ascertainment ‑‑ that is, truly
withdrawn, no ascertainment ‑‑ after that withdrawal, which is down
to four percent in the OPT group and .7 percent in the CRT-D group. And the important number here is actually
what happens in the CRT-D group, because if we missed endpoints there obviously
we ‑‑ we might bias the results in favor of the therapy.
And
as you can see, this number is extremely small and certainly in keeping with
dropout and withdrawal rates in heart failure clinical trials that are
conducted in the most rigorous manner.
Next
slide.
So
this is what happened in terms of withdrawals for mortality. Same numbers up here, starting with 26 and
six. It ends up being 14 for patients
who have had a primary ‑‑ or have not had a primary endpoint. And the bottom line is we end up with only
4.9 percent withdrawn with no ascertainment percentage for OPT, and one percent
for CRT-D. And so 95 percent of
patients in the OPT arm basically are followed to a conclusion.
Next
slide.
And
so the bottom line on this differential withdrawal is shown here. The measures taken ‑‑ an
IRB-approved reconsent process, minimize the impact of withdrawals. In addition, the more complete data ‑‑
these more complete data ‑‑ that is, the data that included the
withdrawal ‑‑ as it turns out were not qualitatively different from
data censored at time of withdrawal.
The
data really didn't change. It's just
more robust. As a result, we do not
believe withdrawals adversely affected the results of COMPANION.
Next.
In
summary, the COMPANION patient population was well balanced across groups. There is no baseline imbalance that could
explain the treatment outcomes. In
COMPANION, there were statistically significant and clinically meaningful
reductions in the primary endpoint of first all-cause mortality or all-cause
hospitalization by 20 percent, a 36 percent reduction in all-cause mortality,
and a reduction in various cardiac morbidity measurements.
And
as I just said, the reconsent process we don't believe jeopardized the trial
and did not create important bias.
Thank
you.
Now,
Dr. DeMets will present some statistical considerations.
DR.
DeMETS: Thank you. I was asked by the Steering Committee to
join you today to make a few comments on some of the statistical considerations
that were raised in the view of COMPANION.
My
primary role in this study was to serve as the independent statistician for
COMPANION. That was done through a
contract between Guidant and the CRO with the University of Wisconsin. That's my only financial involvement other
than payment for the trip to be with you today.
So,
as I said, my primary role is to support the COMPANION Data Monitoring
Committee. I did have the opportunity
to be involved a bit with the protocol design at the beginning, and our
statistical center was the primary source of data for the New England Journal
publication. Some of the analyses that
we did were in fact included in the ‑‑ in your ‑‑ in
the submission.
So
I listed here five issues that sort of were raised to some extent during the
review process, and I'm going to comment on each of them sequentially.
The
issue of proportional hazards was raised, and I'd like to just make a few
comments. First of all, the
Kaplan-Meier curves, which are traditional ways to present time to event, did
not make any assumptions about proportional hazards. And, furthermore, the proportional hazards assumption is really
not required for the log rank test.
That's
testing the null hypothesis. That's a
well-known result in sequential literature.
So that is not a requirement.
There are certainly some ‑‑ certain properties where that's
not required.
As
a footnote, the cost proportional hazards model is ‑‑ the only covariate in treatment. In fact, it is algebraically identical to
the log rank tests. So even for that
particular case it's not required.
Now,
the log rank test certainly has good statistical properties for something we
call a stochastic ordering. To the
non-statistician, one manifestation of that is that the survival curves don't
cross.
So
if you look at the primary endpoint, which Dr. Bristow just presented to you,
the important feature here is that these two survival curves don't cross. This is for all-cause mortality and
all-cause hospitalization. And the
second slide ‑‑ next slide ‑‑ for all-cause mortality
is ‑‑ also, they do not cross.
So
with regard ‑‑ next ‑‑ with regard to the proportional
hazards function, one, it's not required for the log rank test. But even so, the hazards are not drastically
non-proportional. We looked at this
pretty carefully, fitting models, looking at log plots.
But,
in addition, the sponsor asked Dr. Kenny Larntz, who is a consultant to them,
to do some further analysis looking at what he called Schoenfeld residuals, and
the correlation between those residuals in time shows no correlation. So from my perspective, as an independent
statistician, there really aren't any concerns about applying the log rank test
to this particular set of data.
Now,
we often use hazard ratios as a handy statistic to summarize treatment
effect. And, of course, if it's ‑‑
if the model, as appropriate, then, is ‑‑ as I said, it's a very
useful statistic. But even if the
hazard ratio is not constant, the simple hazard ratio is still an average of
those hazards that may perhaps be changing.
However,
one could look at other summary statistics.
And so relative risk at, say, one year is one particular way you could
summarize the effects. So I've done
that for both mortality and mortality plus hospitalization. And as you can see here, the ‑‑
whether you look at the hazard ratio or the relative risk at one year, these
results don't change a whole lot.
Next.
Another
sometimes common way to summarize time to event data is to look at the median
time to failure, and the proper way to do that is to use the Kaplan-Meier
curves and look at the 50th percentile.
For this particular trial, for mortality, we don't have 50 percent
mortality for the patients in this time, so you can't do that.
I'll
just make the comment that you can't just simply take the observation ‑‑
observed failure times and take an average, because that methodology doesn't
take into account staggered entry, censoring, and all of those aspects that are
factors in real survival time in terms of event trials.
Next.
The
issue of hospitalization is another important topic. In survival analysis, all of the methods that we use make a very
important assumption that the censoring that we look at is independent of the
risk ‑‑ underlying risk.
Well, in COMPANION, clearly mortality is a competing risk for
hospitalization, or for any other cause-specific hospitalization for that
matter.
Thus,
the rationale which is traditional in heart failure trials at this point in
time, is to look at death plus all-cause hospitalization, or perhaps death plus
a cause-specific. You can look at
hospitalization alone, and we are often tempted to do that, but just ‑‑
you have to keep in mind that in a formal sense there is a potential for bias
because of the competing risk, and that's certainly the case here in COMPANION.
Mike
‑‑ Dr. Bristow talked a little bit about the post-withdrawal
events. Again here you have to look at
the assumptions that we used to do the analysis. Both the log rank test and the Kaplan-Meier survival curves
assume, again, that censoring is independent of the disease process.
Furthermore,
intention to treat requires that all patients randomized in all events for the
specified endpoint are counted. The
definition is consistent with the ICH guidelines in Document E-9.
We
certainly agree that COMPANION has had informative censoring due to the
disproportionate withdrawal in the censoring related to the treatment arm. Therefore, if you just take the data without
following the patients up post-withdrawal, you really don't have analysis that
is in some sense unbiased. And in a
strict sense, it's not valid.
The
only solution to that problem, and one that's, again, time-honored in clinical
trials, is to try to eliminate or minimize the censoring or loss to
follow-up. So that requires, as I
recommended to the Steering Committee at the conclusion of COMPANION, that they
do everything possible to follow those patients up.
As
Dr. Bristow has shown you ‑‑ next slide ‑‑ for both the
primary endpoint and mortality, we started out with a number ‑‑ 80
in OPT arm and 300 in the CRT-D arm ‑‑ which was from my
perspective an unacceptable high rate to leave on the table. So through the process which you described,
we got that number down to the 12 in OPT and four in CRT-D.
So
it's now down to a number that's ‑‑ while not perfect, it's
certainly consistent with other trials.
And the important point, as you said, is we have four ‑‑
potentially four patients for whom ascertainment from the time of withdrawal to
the end of the study December 1st we don't know.
And
for mortality, again, we whittled it down to 15 versus six. So I think that I commend the sponsor and
the Steering Committee for pursuing this with the vigor it took and the time it
took, but I think you need to get those numbers down to that level to eliminate
any potential for uncertainty.
The
issue of alpha allocation, we have two treatment arms to control here. One can divide the .05 alpha in a variety of
ways. You can divide it in half. In COMPANION, it was divided .03 versus .02,
reflecting the priority and the focus of most importance to the Steering
Committee and to the sponsor.
It
was stated in the protocol clearly, and it was in the sample size section, and
it was discussed and agreed to between the sponsor and the FDA. Survival is, in this study, the leading
secondary endpoint, and in some sense the ultimate endpoint for heart failure
trials. It has been treated as though
it had a separate alpha allocation, and this, again, was discussed and agreed
when the sponsor and the FDA had their pretrial discussions.
The
reason I think this is satisfactory is that mortality is a special
endpoint. It's not one that's subject
to interpretation, modifications, definitions.
And it's the only endpoint that I would grant that special status
to. So it is a secondary endpoint with
its own .05 alpha, as we have interpreted and presented in the trial.
So
from my perspective, the alpha allocation for death and hospitalization is
appropriate, and the same is true for mortality.
The
issue of subgroups ‑‑ subgroups are intriguing, but they always
must be done, analyzed, and looked at cautiously. It's important to remember that subgroups must be defined
properly, and by that we mean using baseline data only. However, even in this setting where we
looked at baseline data, we have had problems historically in our heart failure
trials.
Many
of you are familiar with the PRAISE I and PRAISE II trials ‑‑
properly-defined, baseline-defined, subgroup was identify an ideology, but, in fact,
it was not able to be verified in its subsequent trial in PRAISE II.
Well,
why is that perhaps? Subgroups are
small. The estimates are not reliable,
and you expect some variation. From my
perspective, you should look at subgroups with what I consider an eyeball test,
general overall consistency, don't demand perfect consistency ‑‑
you shouldn't expect it. You can use it
to validate previous hypotheses and perhaps generate new ones.
As
Dr. Bristow showed you in COMPANION for the primary endpoint, these hazard
ratios are generally pretty consistent, all showing sort of a positive effect
with some variation, as you would expect.
Next.
Not
only is there consistency across the subgroups, but to me what was most
remarkable is that COMPANION, like other positive heart failure trials we've
seen, shows a remarkable consistency across the primary and the whole portfolio
of secondary endpoints, whether it's mortality or mortality plus
hospitalization or cause-specific hospitalization, quality of life, life
functions, and so forth.
So
this kind of consistency is what we've seen in other trials that have been
already alluded to such as MERIT, CIBIS-II, COPERNICUS.
To
summarize, the log rank analysis is valid.
Portionality hazards is not required.
Stochastic ordering is really the ‑‑ was really what we
really need. The bias from the
informative censoring was resolved to the extent possible by the followup. I think the allocation of the alpha is
appropriate. Look at subgroups, but
look at them cautiously, and, as I said, the overall consistency for me was
impressive and consistent with other trials that I've been involved with.
Thank
you very much.
DR.
SAXON: My name is Leslie Saxon. I'm from University of Southern
California. My disclosures include the
fact that I receive research funds from the sponsor and serve as an
advisor. I own no equity.
My
task today is to describe, first, the safety of CRT-D, the device used in this
trial. As way of background, the CONTAK
CD device or the CRT-D device used in COMPANION, and the EASYTRAK lead, have
been approved in a patient population with current indications for both CRT-D
therapy and an ICD. This is based on
the results of the CONTAK CD study.
There were no OTR or CRT-P device used in COMPANION, and EASYTRAK lead
have, in addition, been approved for the COMPANION patient population based on
COMPANION exercise substudy data.
Nonetheless,
adverse event reporting in this trial was complete and inclusive, and adverse
events were defined as any undesirable clinical event. Centers were required to report all adverse
events, whether they were related to the device or not. Complications, as a subclassification of
AEs, were defined as adverse events resulting in the need for invasive
intervention to correct, loss of significant device function, death, or
permanent disability. And this was in
accordance with FDA guidelines that were established in 2000.
Observations
were another category of AEs that were defined as events that were resolved
non-invasively and were generally transient or reversible. While system safety evaluation in COMPANION
was not predefined in the protocol, we did evaluate CRT safety according to the
system safety definition, which is that system safety is defined as
complications related to any of the implanted components or their ‑‑
or the associated implant procedure in those patients who were successfully
implanted with the CRT-D system.
This
is measured as the complication-free rate, and this has been used in previous
FDA approved files, and it is measured over a six-month interval
post-randomization. It is considered to
be acceptable at a lower bound of 95 percent confidence interval, if the
complication-free rate is greater than 70 percent.
Other
safety definitions utilized in this trial and others include device
safety. This is a more inclusive
definition than systems safety. It
includes both complications and observations related to any of the implanted
components or associated implant procedures.
This
was reported for all patients, randomized to CRT-D devices as opposed to system
safety, which is all patients implanted.
Patient-related safety is an even broader category, referring to
complications or observations associated with the patient's underlying medical
condition. This AE is reported for all
patients randomized to CRT-D as well as those randomized to optimal
pharmacologic therapy, and this excludes adverse events that are attributable
to the device or the procedure.
These,
then, are the system safety results.
System-related complications were observed in 12.6 percent. This is of successfully implanted
patients. This gives a complication-free
rate of 87.4 percent with a 95 percent lower bound of 85.1 percent. Those events that occurred in greater than
one percent frequency included loss of LV capture observed in 4.6 percent of
patients, los of right atrial capture seen in 1.7 percent, and phrenic nerve
stimulation in 1.5 percent.
The
graph to the right shows the percent subsystem related complication-free rate
at 87 percent, well above the lower acceptance boundary, and equal to or
exceeding that of other performed CRT trials.
This
slide provides the system and device safety data. As I just stated, the system safety percent of patients
experiencing a system safety event were 12.6.
This number increases when including the graph to the right showing
device safety as it includes all patients randomized, not just successfully
implanted, in terms of complications but also expands the definition to include
observations listed to the right.
Patient-related
safety ‑‑ the more inclusive category of all patients randomized
according to the total complications and observations, are shown in this
slide. That's why the numbers are
somewhat higher. This would include a
total of all complications and observations in the OPT group versus the CRT-D
group for more serious complications, and then observations given on the right.
This
table illustrates the system-related adverse events in all patients
successfully implanted through ‑‑ from randomization to six months
that occurred greater than one percent of the time. The columns in yellow indicate ‑‑ I would draw your
attention there ‑‑ indicate those instances that required an
intervention or resulted in a loss of therapy.
So
while phrenic nerve stimulation was observed in 60 patients, it only required
invasive intervention in three. And in
one patient, it resulted in loss of therapy due to the need to turn or not to
cause ‑‑ not to have LV stimulation due to persistent stimulation.
Loss
of LV capture threshold was observed in 36 patients, and the majority of this
did require a reintervention but was successfully resolved in all but three
instances. Loss of RV capture and loss
of right atrial capture were also seen and is consistent with other device
trials.
Okay. The next slide indicates procedure-related
adverse events in all patients randomized, and includes things such as
post-surgical wound discomfort, hematomas, and coronary sinus traumas. What should be noted, again, is those that
required invasive intervention or resulted in loss of therapy. Coronary sinus venous trauma did result in
the need for invasive intervention in 1.2 percent of patients but did not result
in loss of therapy, only an instance of device infection required, loss of
therapy due to the need to remove the device.
We'd
now like to address the Steering Committee's response ‑‑ we'd now
like to provide the Steering Committee's responses to the FDA questions. The background to this is that the Steering
Committee felt strongly that it would be helpful to the FDA to comprehensively
address the reviewers' questions as part of our presentation.
The
sponsor shared the FDA Director's comments with the Steering Committee, and the
FDA encouraged the sponsor to address these questions through the thoughts of
the Steering Committee members.
Let's
start with the first question from the FDA reviewers, which relates to the
hospitalization definition. Number one,
please comment on whether modifications to the hospitalization definition
impact the interpretation of the primary endpoint. The Steering Committee feels that the hospitalization definition
has been applied consistently throughout the trial.
The
original case report forms dated 1999, and submitted with the initial IDE, have
the date of hospital admission and discharge and included a note of four-hour
need for IV inotrope or vasoactive therapy.
Therefore, the hospital data are complete, and the definition was, in
fact, consistently applied for the entire study population.
Further,
the primary efficacy endpoint hospitalization piece was not, in fact, modified
three times or changed three times as was mentioned in one of the reviewer's
comments. Rather, the primary endpoint
remained the same throughout and included, again, any death, any
hospitalization with a calendar date change or use of IV inotropic or
vasoactive therapy lasting greater than four hours, administered in an
outpatient setting, to treat decompensated heart failure.
Adjudicated
events needs to have precise definitions for verification and
consistencies. Endpoint Committees
typically provide these definitions, and these definitions are typically, in
addition, refined early in the trial as was the case after four percent of the
hospitalizations were adjudicated in this trial.
Two,
hospitalization definition impact.
Please comment on the impact of modifications to the hospitalization
definition on the interpretation of the secondary endpoint of mortality. The independent Steering Committee does not
agree that the hospitalization definition was, in fact, modified. The validity of the primary endpoint
definition, and, therefore, its statistical significance allow for analysis of
secondary endpoints.
Further,
the all-cause mortality endpoint, as Dr. DeMets suggested, represents a
particularly robust outcome and has been a historical gold standard for heart
failure device trials.
Three
‑‑ are the data from the COMPANION clinical trial sufficient to
support an expanded patient population for the sponsor's CRT-D device? The Steering Committee feels that this was a
large, multi-center clinical trial properly and rigorously conducted under the
guidelines of an independent Steering Committee, Data Safety and Monitoring
Board, statistical group, and Mortality and Morbidity Committee.
The
trial design employed an endpoint of all-cause mortality or all-cause
hospitalization. The conservative
nature of this endpoint required a higher standard of clinical evidence to demonstrate
effectiveness. The results are
sufficient to support expanded indications as demonstrated by meeting both the
primary and secondary endpoint and, in addition, demonstrating remarkably
consistent, multiple relevant positive endpoints across multiple subgroups.
Four,
indications for use. With respect to
statements in the indication for use regarding the primary endpoint ‑‑
A) Are the data from COMPANION sufficient to support claims based on the
primary endpoint results? This study
demonstrated a statistically significant 20 percent reduction for the primary
endpoint of all-cause hospitalization or all-cause mortality and support the
claims. The secondary endpoint events
were consistently adjudicated by the independent Mortality and Morbidity
Committee.
B)
If so, please comment on whether the language of the proposed indications for
use statement adequately describes the endpoint. In particular, please discuss whether the term "all-cause
hospitalization" is appropriate.
We feel that the language accurately describes this endpoint. The definition of all-cause mortality is
identical to that employed by the Morbidity and Mortality Committee in the
adjudication process.
In
addition, we feel that it is a more conservative and more comprehensive
methodology than what is typically used or may be used in other heart failure
trials such as a cardiovascular or heart failure hospitalization endpoint, and,
importantly, is consistent with the pretrial mandate of the FDA.
Five,
with respect to statements in the indication for use regarding the secondary
endpoint of mortality, are the results from the COMPANION clinical trial
sufficient to support a mortality benefit claim for the sponsor of CRT-D
devices in the COMPANION population?
The
study demonstrated a statistically significant reduction in time to all-cause
mortality of 36 percent. This
improvement is in addition to the benefit conferred by optimal pharmacologic
therapy. Therefore, the mortality
results support this indication.
Six,
please comment on whether the CRT-D labeling should characterize the total
number of hospitalizations and length of time patients spent in the hospital
for the CRT-D and OPT arms of the companion trial. No, we do not think the labeling should reflect this, because the
issue of competing risk makes analysis of hospitalization days alone
problematic and inaccurate.
E)
If so, please comment on whether device implant hospitalization should be
included as part of that analysis.
Again, no, in terms of device implantations. The FDA did approve the study design, which specifically excluded
implant hospitalizations from analysis, because to do so would be to give each
patient a primary endpoint event at the time that they were admitted to receive
device therapy.
However,
adverse events reporting occurred from the time of randomization and was
comprehensive and complete, not from successful device implant as has been
employed in other trials. And,
therefore, all adverse events were captured and reported in the analysis. Thus, the implant hospitalization and risks
are adequately addressed in the proposed labeling.
Seven,
please comment on whether the CRT-D labeling should present adverse events from
the CRT-D and OPT arms of the COMPANION trial in a consolidated manner that
would allow their comparison. The
safety of previous CRT-D devices that have been approved has traditionally been
based on the system safety definition ‑‑ that is, complications
related to the implanted system. It is
consistent with that methodology.
The
proposed summary of safety and effectiveness currently lists adverse events
from both groups. The sponsor has
indicated to the Steering Committee that they are willing to work with the FDA
to prepare an appropriate format for accurately presenting adverse events. That is consistent with the pre-agreed
investigational plan.
Eight,
please comment on whether data obtained from patients after withdrawal should
be used in any of the analyses described in the device labeling. Again, we emphasize that this trial was
designed as an intention to treat trial.
Thus, all data must be included to avoid bias. And any treatment comparison that does not include all events is
not valid.
In
the COMPANION trial, these efforts to complete the data set were designed, in
fact, to minimize bias, due to the differential withdrawal rate observed in the
OPT group. The Steering Committee felt
that it was obligated to make every reasonable effort to ascertain the primary
event status of the withdrawn patients.
I'd
like to conclude by stating that the COMPANION study incorporated a primary
endpoint of all-cause mortality and all-cause hospitalization. That is the most rigorous evaluation of CRT
therapy performed to date. When added
to optimal pharmacologic therapy in patients with moderate to severe heart
failure, left ventricular dysfunction, and QRS delay, time to all-cause
mortality or all-cause hospitalization was significantly reduced by 20 percent.
Time
to all-cause mortality was significantly reduced by CRT-D therapy ‑‑
has a ratio of .64 by 36 percent.
Finally,
CRT-D is safe for use in this patient population, with a safety profile similar
to or exceeding that demonstrated in prior CRT-D studies performed in less
advanced heart failure patients.
That
concludes our comments on the Steering Committee.
ACTING
CHAIR LASKEY: Thank you very much,
folks. That was all-encompassing.
I'd
like to, at this point, ask the panel ‑‑ we're actually right on
schedule. So before we take a break at
11:00, we potentially have a few minutes up here to query the sponsor for the
usual burning issues.
Dr.
Brinker?
DR.
BRINKER: I realize and agree with the
concept that the initial hospitalization for device implant did not count
against hospitalization. What I'm a
little bit uncertain of is, if a patient had an unsuccessful primary implant,
and had as many ‑‑ well, numerically many, maybe not
proportionately many, patients had one or two or even three more implant
attempts, were the subsequent implant attempts counted as hospitalizations?
DR.
FELDMAN: Yes. We can actually show you the absolute numbers on that. They are important to look at ‑‑
if that's okay.
Leslie,
do you want to ‑‑
DR.
SAXON: In order to maintain consistency
related to this concept of not primary endpoint of ND patients for devices, we,
in fact, did not count the second attempt.
So there were initially 15 percent of patients who were not successfully
implanted. Those that were taken back
included ‑‑ excuse me. I
want to just look at this.
So reattempt was not done in 31. The remainder ‑‑ 50 ‑‑
were taken back for a second attempt, and that ‑‑ that was
considered an index hospitalization for implant and not counted.
DR.
BRINKER: I can understand from a
physiologic point of view that studying the disease while you review that ‑‑
it seems to me that the impact of the second procedure has as much morbidity,
if you will, associated with it, possibly more, than a four-hour
hospitalization for a vasoactive drug in an emergency room. So I'm concerned a bit that the bottom line
doesn't reflect that.
DR.
FELDMAN: Well, I think, first of all,
we're looking at endpoints not over a short window of time, which is what
you're looking at with a reimplant. But
in this trial we were really looking at endpoints over a very long period of
time. And the two endpoints that we're
most concerned with in caring for a heart failure patient is either mortality
or hospitalization.
We
want patients to live longer, and we want them to feel better. So I think we recognize the fact that
upfront there is a certain procedural intervention that is associated either
with putting the device in, or in a very small number of patients putting a
device in a second intervention if you will.
But over the long term we're looking at what happens to these patients,
and I think that's a more appropriate comparator.
DR.
BRINKER: Well, let me just take this to
‑‑ a little further. I
think that a second and third and perhaps even fourth reoperation for a failed
implant is not a short-term issue necessarily, number one. Number two, we are looking at single events
as indices of an endpoint, in terms of hospitalization.
So
one issue would be that these single events in some ways are used as surrogates
for the likelihood of the patient having a worsening ‑‑ a worse
clinical status that extends beyond that single event. And that's one justification for treating in
a single hospitalization as an endpoint, if it got heart failure therapy, let's
say, for four hours versus a second implant.
But
I ‑‑ it's not absolutely clear to me that one single
hospitalization for four hours of vasoactive therapy is, in fact, an issue that
indicates a worsened ‑‑ prolonged worsened state of heart
failure. So one question that I would
ask you is: do you have any information
about cumulative per patient hospitalizations?
Does
one hospitalization always mean that over a period, a year or two, that these
people would be repeat? Or did many of
them, in fact, have only one hospitalization?
And that would be equatable to a repeat surgical procedure for implant.
DR.
BRISTOW: Before we address that issue,
let me just add a little more comment on your first point. The patients in the OPT group who dropped in
for devices, those hospitalizations, those elected an implant hospitalization
also didn't count. So we consistently
applied the standard that if it was an implant hospitalization, done
electively, out of the context of any other reason to hospitalize, that
wouldn't count, just like it ‑‑ up front, so that ‑‑
DR.
BRINKER: Well, but again, I make the
differentiation between a primary implant, which is ‑‑
DR.
BRISTOW: Right.
DR.
BRINKER: ‑‑ I agree should
not be counted against it.
DR.
BRISTOW: Right.
DR.
BRINKER: But second and third means
that there was a problem with the first, and that being assigned to that
therapy imposes an additional risk.
DR.
BRISTOW: Well, and that could possibly
be. We'll try to comment further. But I want to make the point, shown on this
slide, that an implant hospitalization is not the same thing as any other kind
of hospitalization for a heart failure patient.
So
this gives the duration in days of hospitalization for implants. And notice the implants in the OPT
group. These are the drop-in implants
around three days versus what happens with a medical hospitalization if you
will, getting up close to eight days' duration.
So
it's a completely different thing in terms of the impact on a patient and what
it means in terms of natural history, we would argue, whether it's a device
implant related or it's a real medically-driven hospitalization.
Now,
in terms of what happens, if you get hospitalized once, does that set you up
for subsequent hospitalizations? The
answer for a heart failure patient is yes.
What can we provide from COMPANION to support that? We have the multiple hospitalization backup
slide.
We
don't have ‑‑ we probably can't give you direct evidence that
you're looking for. But as you'll see
on the clustering of number of hospitalizations, there are many patients
hospitalized multiple times, which is the expected ‑‑ one
hospitalization begets further hospitalization. That's, in fact, why we have that as an inclusion criteria,
because we know it increases the event rate for hospitalization to have a
historical hospitalization by two- to threefold in fact, as well as a mortality
rate.
DR.
FELDMAN: While we're looking for that,
let me make one other comment, and then I think Dr. Saxon wants to make a
comment as well. You mentioned the fact
that there were three or four attempts in patients. In fact, only three patients had a second attempt. No patients had three or four attempts, and ‑‑
DR.
BRINKER: My reading of that was that ‑‑
you mean a second attempt after the first one.
DR.
FELDMAN: Right. Here's the actual data.
DR.
BRINKER: So that's three. That's three procedures.
DR.
FELDMAN: Right.
DR.
BRINKER: That's what I was referring
to.
DR.
FELDMAN: But that only occurred in
three patients.
DR.
BRINKER: Right.
DR.
FELDMAN: And here is the data. So you can see that ‑‑
DR.
BRINKER: But two occurred in, what, 15
percent, did you say?
DR.
FELDMAN: No, no, only ‑‑
excuse me ‑‑ 8.4 percent.
So here's the actual data.
Here's 98.8 percent, here's the success rate for the first attempt,
here's a first reattempt and the success rate, and here's the second reattempt
and the success rate. But here you only
see three patients, and here you only have 50 patients out of a total of 588
patients. So a very small number had to
be ‑‑
DR.
BRINKER: Well, in here it's eight
percent had at least one more, and half a percent had at least two more. So these, as you know from watching some of
these procedures, especially ones that are complicated the first time, can be
long duration, high radiation exposure, a lot of other morbidity, both on the
patient and the physician.
So
they're not easy things, and I was just trying to equate this with the
four-hour drug ‑‑ now, the fact has been brought up that the
average time in the hospital for events, where it was actually quite long mean
time, in the range of eight days, suggests that actually the ‑‑
suggests to me at least something that I didn't see quickly before in your
data, and that is that the absolute number of ER or physician visits that
resulted in a four-hour infusion made up presumably a very small number of the
actual hospitalizations.
DR.
BRISTOW: Yes, 2.5 percent of the total
primary endpoints. 2.5 percent on the
average between the two treatment arms was ‑‑ the IV was really a
trivial number of events as a contributor to the primary event.
DR.
FELDMAN: Leslie, do you want to
comment?
DR.
SAXON: Just a couple of additional
comments specific to your concern related to the second first attempt. Number one, we did capture all significant
morbidities that may have occurred as a result of that second attempt
hospitalization. While the
hospitalization didn't count against the primary endpoint, any badness or major
morbidity associated with that was, in fact, counted, as was every AE that was
then adjudicated by the Data Safety and Monitoring Board.
The
other piece is that because we understood what this procedure involved, and I
myself have implanted many of these devices, what we encouraged investigators
to do in the trial was if the trial exceeded four hours, or there were issues
related to difficulty in cannulating the cornerstones or one of the other
technical pieces, that they feel free to bring the patient back.
So
a reattempt was considered something that could occur in order to limit implant
time, limit potential morbidity, and this was the consensus after looking at
the early data and just with our knowledge of the procedure itself. So I think that the ‑‑ you know,
to focus on that second attempt as being a potentially more morbid event is, in
fact, not true in many of the cases, that we encourage people to stop, think
about the case, and take the patient back, rather than ‑‑ if that
patient had any particular features that were ‑‑
DR.
FELDMAN: Mike, did you find that
slide? Okay.
ACTING
CHAIR LASKEY: Thank you.
Dr.
Krucoff, do you have ‑‑
DR.
KRUCOFF: Just a quick question about
the communication pattern. I'm sure,
being as it's you guys, you can understand one of the things we're going to try
and do or wrestle with is to understand where all of these changing definitions
or just issues seem to have arisen between what you know is coming in the FDA's
view of the strong events, and ultimately have an understanding.
You
had a couple of slides that were put up on data flow process, and several of
you have commented on that. And I
wonder, is anybody here from the external CRO?
Or can anybody help me understand the background link of what data
flowed from the external CRO to the sponsor, and ultimately, along the way,
what the process was, then, for communicating as definitions were refined or
evolved over the course of the trial in communicating back to FDA?
MR.
WHITE: Hi. I'm Bill White, President and CEO of C2R. We were the external CRO involved with this
trial. As the slide presents, what we
were entailed with doing ‑‑ what we did for the M&M Committee
was very simple. We collected all of
the case report forms that came in from the centers, and then we went through a
laborious process of accumulating the discharge summaries and the supporting
documentation and hospital records.
We
prepared case narratives for every case.
That included a summary of the hospitalizations, all the case report
forms, all of the documentation, and we prepared those in booklets for every
meeting. The meetings were then
scheduled on a routine basis with the committee, at which time we would send
the books out from our office to the members of the committee.
We
would send individual booklets to the primary and secondary reviewers, and they
would make all booklets available to the committee for the meetings. During the meetings for the M&M
Committees, we were always present, minutes were taken, all of the votes ‑‑
the material was reviewed, the adjudication process was documented, case report
forms were filled out, all case report forms for the adjudication process were
then signed by the Chairman, which is Dr. Carson.
At
that point, all of the books were retained by us, and brought back to our
office. At that point, what we did with
the data was that data became part of the official database, in our clinical
trial database, and that data was forwarded on a period basis with our monthly
transmittals to the independent statistician, Dr. DeMets' group.
We
did not forward any data at any time to the sponsor. The data always went from our office, from the M&M Committee
case report form, to the independent statistician who did his analysis and then
reported it to the Data and Safety Monitoring Board.
So
that's what we did.
DR.
KRUCOFF: Okay. So then, David, your data would go directly
to the DSMB, one way?
DR.
DeMETS: Yes. We prepared sort of an additional detailed monitoring report,
which covered things from recruitment to primary safety, the whole double
package, and we reported to the Monitoring Committee. At no time did we communicate anything about those reports to the
sponsor. The only communication was with
the Data Monitoring Committee, with the one exception that was noted when we
had a discussion with the FDA about a different matter.
DR.
KRUCOFF: That was the coronary
sinus ‑‑
DR.
DeMETS: Yes, that's right.
DR.
KRUCOFF: Okay. And then, is it fair to say ‑‑
can somebody say the feedback from the line from DSMB to Steering Committee is
simply the sort of go/no-go kind of communication, generic ‑‑
DR.
DeMETS: Yes. The Chairman of the Steering Committee wrote a very perfunctory
letter saying the committee met, reviewed the data, and recommended to
continue.
DR.
KRUCOFF: And then, the Steering
Committee to the sponsor communications, can somebody characterize what those
were likely to be?
DR.
BRISTOW: Yes. The sponsor had a representative in an ex officio sense on
Steering Committee calls. And whenever
the Steering Committee ‑‑ in addition to that, whenever the
Steering Committee thought there was an issue requiring sponsor input, we would
communicate with them directly.
DR.
FELDMAN: Does that ‑‑
DR.
KRUCOFF: That was very helpful. Thanks.
Maybe we can get ‑‑
ACTING
CHAIR LASKEY: Yes, Dr. Yancy.
DR.
YANCY: Just two questions. The first one is within the context of what
Dr. Carson shared with us. Looking at
slide 56, it's evident that the actual admit rates were higher than
projected. And so for clarification
purposes, since Dr. Saxon addressed the hospitalization question quite
substantially, was the change in hospitalization more an operational change, so
that it would be easier for them to track and follow as opposed to trying to
enrich the event rate?
Because
that has been a problem of a number of heart failure trials, and has
necessitated a change in hospitalization.
It looks as if this was more for the purposes of accurate data tracking. If you could just clarify that, if you
would.
DR.
CARSON: Yes. The change in the completing of the definition, if you will, for
hospitalization, then, was related to trying to make verifiable data possible. We had thought that a 24-hour endpoint would
be a reasonable one to use. And as I
had said in my comments, during the previous trials that had used this endpoint
‑‑ maybe we could just go to backup slide 2.
This
had been the endpoint that had been used.
This was the way the ‑‑ the definition, really, for
hospitalization has been an evolving one.
You are very well aware that all-cause mortality had been the gold
standard for trials for many years.
We
didn't really see hospitalizations being adjudicated or included in primary
endpoints, really, until the PRAISE trial in 1993. And that had a ‑‑ CV morbidity was a hospitalization
for life-threatening CV cause, and it was for greater than 24 hours.
MERIT
heart failure did all-cause mortality and all-cause hospitalization, and they
started with a visit that was described in the protocol as being greater than
24 hours. But yet, if you look in their
methods ‑‑ their methods paper, you find that the Endpoint
Committee added a calendar date change if the dates ‑‑ if the times
couldn't be verified.
VALHeFT
had nothing in the primary protocol about time of hospitalization. The Endpoint Committee added on 24-hour
duration, and then I chaired that committee and we realized that we weren't
getting verifiable discharge times in many patients, particularly foreign
sites. So we went to a calendar date
change.
And
then ‑‑ now, COMPANION fits in a little bit between VALHeFT and ‑‑
I have Overture on the bottom there.
And we thought because we were at U.S. centers that we might be able to
get admission and discharge times. The
data, as you saw on the adjudication form, was in terms of calendar date
change. When the committee looked
within the records and tried to find the discharge times, we found that we
couldn't always do that.
And
we felt we were vulnerable, then, to a group coming back and saying to us,
"Well, could you really verify that these were 24-hour times? Could you really get the discharge
times?" We would have had to say
we couldn't always get those.
So
we felt that a 24-hour date change was not something that was verifiable enough
for this endpoint, and we felt that a calendar date change, which had then been
evolving into being really the standard for clinical trials, was what we should
use. That was after a small number of
events had been done, so it was entirely for date clarity.
DR.
DeMETS: Just a further comment. We didn't convey any sense of event rates to
anybody. It would have been difficult
for them to keep score. They perhaps
could have with a ‑‑ but they ‑‑ it wasn't something
they were aware of the dates, so they didn't know anything about event rates at
that point in time.
DR.
BRISTOW: Well, I will underscore
that. We have been under the assumption
that it was going to take 2,200 patients to achieve this 1,000 target events. And, in fact, when we were called in to the
DSMB in November 2002 and said that you've got your target number of events, we
were, frankly, shocked that the event rate was that high. We had no sense that the event rate was that
high on the Steering Committee.
DR.
YANCY: One other question, Dr.
Carson. Given the threshold that you
set for the calendar date change, do you have any feel for the number and the
kind of clinical experiences that didn't met that threshold? Were these just parenteral diuretics for a
slight change in symptoms? Was it a
large number? Small number? Do you have any feel for those that didn't
reach that threshold?
DR.
CARSON: We would ‑‑ because
the data that was collected was in terms of a calendar date change from the
sites, we would not have had events that then we would have excluded.
I
do have to say that, as I have thought about this in multiple clinical trials,
I would have to say that these events would have to be exceedingly rare in
which a patient would be admitted to the hospital, not treated in an outpatient
setting, but admitted to the hospital, and then discharged sometime late at
night after therapy.
It's
not a practice I am familiar with as a practicing clinical cardiologist for
close to 20 years. And I think within
the clinical trial milieu you have to be exceedingly rare. This has been of concern previously. This was brought up when VALHeFT presented
its data in 2001, and at the time we did not have data then either. No clinical trial has really presented ‑‑
has really collected data that I know of on these kind of events.
The
VALHeFT question before the panel in 2001 did bring up the issue, and the
Overture trial, for example, went back and looked at their heart failure
hospitalizations and found a very small number of them that were, in fact, less
than a 24-hour period or did not involve a calendar date change. So I'm afraid I don't have any data beyond
that.
DR.
YANCY: No, that's helpful. It seems as if it was, then, largely
operational. I just have one short
question for Dr. Saxon. It has to do
with the safety issue. The chart that
is slide 99 shows that the coronary venous trauma occurred in 3.7 percent of
cases. And it appeared to be of no
really meaningful consequence.
I'd
just like to understand if those were episodes of tamponade that were just
monitored or if these really were inconsequential with just extravasation of
dying. Can you just help us understand
that? At first glance, it seems like it
would be a fairly traumatic event. But
it seems as if the consequences were less so.
DR.
SAXON: Great. I'm happy to answer that.
Let me just reflect back to your question to Dr. Carson, which was what
was sort of types of things that occurred in this trial that might ‑‑
that occurred in this trial that might not meet the calendar date change.
And
one thing we could look at would be, for instance, lead revisions for any
reason. Thirty-six of the 50 lead
revisions did trigger a calendar date change, so a minority didn't, just to
give you a sense of those types of events.
Related
to coronary sinus trauma, you're right, the majority of coronary sinus venous
traumas, which were carefully classified in this trial as either dissections,
meaning that there was simply dye in the lumen of the vessel, a perforation
indicating that the dye was free-flowing beyond the vessel but did not require
an intervention, required observation alone, and in some instances one even
proceeded with the implant, who had tamponade would be defined as requiring an
intervention or resulting in some type of event.
So
when you look at coronary venous trauma, the majority of those events were
staining or required a non-invasive or just an observation period for
resolution. But some of them ‑‑
some of the perforations as well as obviously the tamponades did require some
type of invasive procedure to correct.
DR.
YANCY: Thank you.
ACTING
CHAIR LASKEY: Dr. Somberg, and then
we'll take a break.
DR.
SOMBERG: Dr. Bristow, you were
discussing the issue of the availability of devices in the course of the trial,
and that this was considered a problem because people might want to take their
patient out of the study and give them the benefit of something that was
approved.
For
that reason, it was introduced ‑‑ if I'm paraphrasing you
correctly, it was introduced ‑‑ the concept that to do that there
would have to be a worsening of congestive heart failure, and that would have
to be an indexed hospitalization.
With
that said, wouldn't that then be sort of an admonition or a call to increase
the number of hospitalizations in the CRT-P group? And if that be the case, or possibly the case, can you show me a
data breakdown of the number of hospitalizations in CRT-P before that edict was
announced and after it?
DR.
BRISTOW: Well, I can't pinpoint the
data. All I can say is that the primary
event rate was linearly consistent over time.
That is, there was no inflection of the primary event driven by
hospitalizations ‑‑ 90 percent of the primary events
hospitalizations. There was no change
in the primary event rate over time in the OPT group, and ‑‑
DR.
SOMBERG: Am I right to assume that was
sort of like a midpoint decision in the trial?
Because looking at that peak of entry, and then a decline rapidly ‑‑
DR.
BRISTOW: Yes. So that obviously ‑‑ that decision had to be made
after these devices were available. So
it's ‑‑ you saw the enrollment per month, a bell-shaped curve, and
it was beyond the peak of that bell-shaped curve and we began to institute
these measures. And it did not lead to
an increase in the number of primary endpoints.
And
I can tell you that, you know, we often rejected the data as not being
adequate. They had to provide an
admission note if the patient was in the hospital, clearly showing that there
was progression of heart failure. They
had to provide data on the treatment of heart failure, which had to be
substantive. That is, it had to be IV
therapy such as IV Lasix, for example.
Backup slide 19.
So
this was a very stringent process. The
Steering Committee was aware that this had the potential to, as you paraphrase
your thoughts, create endpoints. But I
don't believe this actually did based on the stringency of the process.
And
I will also say that the investigators were strongly encouraged to maintain
their equipoise. So here are cumulative
‑‑ this is cumulative by month.
So that's not ‑‑ there's another ‑‑ yes, you
don't see a turn up anywhere. Log log
plot would be good. There's no spike,
there's no up-tick in that curve, and there are better curves to look at perhaps.
But
what I was saying ‑‑ okay.
Now, that last little point is out there where there's maybe one patient
left in the OPT group out there at the end.
So that needs to be ignored. But
‑‑
DR.
SOMBERG: Doesn't this need to be at a
flexion point of 5.5?
DR.
BRISTOW: So there wasn't any change in
event rate over time. And, again, the
investigators really did a great job of maintaining their equipoise. Our message to them was, we haven't proven
this therapy works in this kind of advanced heart failure population.
And
the data that you're seeing or that led to the approval of these devices were
based on much less sick patients. These
were not hard endpoints. This wasn't
true intention to treat from the start of randomization ‑‑ none of
these data. And I would say that 95
percent of the investigators truly believe that and maintain their equipoise.
All
right. Here we go. This is the best slide for this
purpose. This is the actual rate by
month, and you can see the OPT group is not up-ticking anywhere.
ACTING
CHAIR LASKEY: Well, it's a notable
finding, because this panel has seen expansions in use of devices shortly
following the approval. So this would
be certainly unique and an exception.
But ‑‑ do you have one more question?
DR.
SOMBERG: Yes, I have one more. The other thing was it was mentioned the
duration of hospitalizations might be different between the initial implant and
the CHF therapy. I wonder if you have
the data in terms of duration of hospitalization for the CRT-D versus the CRT ‑‑
DR.
BRISTOW: Yes. We showed earlier ‑‑ data we have to show you we had
on earlier.
DR.
FELDMAN: Here it is.
DR.
BRISTOW: Here is what we have. And so this is implant hospitalizations,
elective implant hospitalizations, in either group, drop-ins in the case of
OPT, and then CRT-D upfront or reimplant attempts versus medical
hospitalization that were part of the primary endpoint.
DR.
SOMBERG: Yes. But I'm asking to see the total hospitalizations of the two
groups in terms of duration.
DR.
BRISTOW: Okay. We have ‑‑ that would be in the
morbidity data we showed. So just give
us a second; we'll pull that up.
Again,
as has been alluded to a couple of times, looking at hospitalization data in
isolation in a trial where there's a competing risk of death of
problematic. And so we always start
with a disclaimer. But if you go to the
right, this cardiac morbidity is in hospitalized patients is how it was
done. So it's the duration of ‑‑
it's not purely hospitalization. It's the
duration of the event driven by hospitalization.
And,
obviously, there seems to be a difference in favor of CRT-D. It's not exactly what you're looking for,
but it's driven by what you're looking for.
ACTING
CHAIR LASKEY: Great. Thank you.
I
have 11:15. Let's regroup at 11:30 and
have the FDA presentation.
Thank
you very much.
(Whereupon, the
proceedings in the foregoing matter went off the record at 11:18 a.m. and went
back on the record at 11:34 a.m.)
ACTING
CHAIR LASKEY: We're doing well, folks,
if we can take our seats and resume.
Thank you. I promise that
everyone gets where they need to be this afternoon, so let's move forward.
DR.
FARIS: Ready to get started.
ACTING
CHAIR LASKEY: Thank you, sir.
DR.
FARIS: Good morning. My name is Owen Faris and I'm FDA's lead
reviewer for this submission in which the sponsor is seeking expanded
indications and claims for their CRT-D devices. The physical reviewer for this submission was Dr. Barbara
Krasnicka. The clinical reviewers were
Dr. Scott Proestel and Dr. Ileana Pina and bioresearch monitoring was directed
by Rachel Solomon. The regulatory
background for the COMPANION clinical trial is extensive and includes the
following important events.
The
COMPANION was approved under a binding agreement between the sponsor and FDA
formalized September 8th, 1999. On
January 20th, 2000 the first patient was enrolled. On May 2nd, 2002, the sponsors CONTAK CD device received FDA
approval. On November 30th, 2002, the
COMPANION trial was stopped for reasons previously discussed by the
sponsor. On January 26th, 2004, the
sponsor's CONTAK TR, Renewal TR devices
received FDA approval. Thus, at that
point, both devices which had been studied in the COMPANION trial were market
approved.
On
March 26th, 2004, the submission currently under review was received by
FDA. The formal agreements between FDA
and the sponsor regarding the COMPANION clinical trial included agreement on
the inclusion and exclusion criteria, the primary and secondary hypothesis and
the statistical analysis plan. It was
agreed that the statistical plan would not support CRT-D versus CRT-P
comparison. In addition, to address the
issue of multiplicity, the statistical plan required consistency across the
primary and secondary end points in order to evaluate the results from any one
end point.
The
sponsor's proposed indication requests the following changes based upon results
from the COMPANION clinical trial; an expanded indication to include the entire
population described in COMPANION and new claims based on the primary composite
end point as well as the secondary end point of mortality.
The
proposed indication reads as follows; Guidant Cardiac Resynchronization Therapy
Defibrillators are indicated for patients with moderate to severe heart
failure, NYHA III/IV, and remain symptomatic despite stabile optimal heart
failure drug therapy and have left ventricular dysfunction, EF less than or
equal to 35 percent and QRS duration greater than or equal to 120 milliseconds. Guidant Cardiac Resynchronization Therapy
Defibrillators have demonstrated the following outcomes in the indicated
patient population specified above.
Reduction in risk of "all-cause" mortality or first
"all-cause" hospitalization, note hospitalization is defined as
administration of IV inotropes or vasoactive drugs greater than four hours
outpatient or inpatient or admission to the hospital that includes or extends
beyond a counter date change, reduction in risk of "all-cause"
mortality, reduction of heart failure symptoms.
FDA's
review covered the following areas; COMPANION primary and secondary end point
results, COMPANION hospitalizations and adverse events, consistency with a
pre-specified clinical and statistical plans and presentation of data and
device labeling. At this time, I would
like to introduce Dr. Barbara Krasnicka to present FDA's statistical review.
DR.
KRASNICKA: In my presentation, I will
focus in on the problems connected with the study design, data quality and
study scholar analysis. As it was
mentioned before, the objective of this study was to demonstrate the safety and
effectiveness of the OPT plus CRT-D and OPT plus CRT-P through the comparison
with OPT alone. In this statistical
review, only a comparison of CRT-D versus OPT will be presented. As mentioned before, the COMPANION trial was
a prospective multi-center randomized study on patients suffering heart
failure.
The
clinical trial for all the group, sequential design. The study was planned to stop after 1,000 primary end point
events would be identified. It was
expected that compared to the OPT alone, the CRT-D could reduce combine
"all-cause" mortality and "all-cause" hospitalization which
was the primary effectiveness end point.
And "all-cause" mortality and cardiac morbidity which were the
secondary effectiveness end points. The
safety end point was not specified.
Quality
of data is influenced by clear definitions of response variables and methods
used towards data collection, editing and assessment. The primary effectiveness end point was
modified three times during the study.
The end point was originally defined as "all-cause" mortality
and "all-cause" hospitalization where "all-cause"
hospitalization was defined as admission to a hospital for any reason. In addition, this end point would include
emergency room visits that resulted in IV therapy. "All cause" hospitalization definition was finally
revised as the one for which the discharge date was different from the
admission date or as hospitalization longer than four hours during which
patients received IV therapy.
The
collection of hospitalization events was based only on admission and discharge
dates, not taking into account exact time.
Therefore, the capture of hospitalization event longer than four hours
during which patients receive IV therapy, was based on the duration of the IV
therapy as recorded in the follow-up case report form.
However,
some hospitalization events did not have a case report form. Therefore, there are some concerns that such
events may not be captured. The study
stopped in December 2002. Some patients
were followed up only for a few weeks or days.
At the moment of trial stopping 941 primary end point events had been
submitted. This means the target number
of primary events had been approximately reached. However, there were many withdrawals from the study. The withdrawal rate was especially high in
the OPT group. At 12 months, it was 21
percent in the OPT group but only four percent in the CRT-D group.
FDA
is concerned that worsening of patients health status was probably the reason
for many withdrawals. Due to many
withdrawals and an imbalance between the two treatment groups in the number of
withdrawn patients, the withdrawn patients were asked to consent again to
collect end points data and status. FDA
is concerned that post-withdrawal information regarding hospitalization may be
unreliable.
The
differences between groups with respect to the primary effectiveness end point
and all "all-cause" mortality work is low grant statistics. Kaplan-Meier method was applied to estimate
the survivor functions for the two groups and the Cox Model was used to
estimate hazard ratio. In the case of
cardiac morbidity and adverse events, mainly the exploratory analysis were
performed.
Now,
let us discuss the statistical analysis of the primary effectiveness end
point. This means analysis related to
combine "all-cause" mortality and "all-cause"
hospitalization. The data set contained
202 and 386 primary events in the OPT and CRT-D arms respectively. It is worth noting that the primary end
point was driven mainly by hospitalization events which constitute over 92
percent of all primary end points.
This
slide shows the class of estimates of event free functions based on the
Kaplan-Meier method. The figure demonstrates some separation of both curves
over time but the curves are clearly separated only in a period of time, about
one year after randomization. After 800
days, the estimations are based on the relatively small number of observations
and may be unreliable.
To
perform meaningful survivor analysis, for example, to apply the Kaplan-Meier
method, some assumption should be made, among other assumptions are quality of
data set was good, the primary effectiveness and definition was not changed,
and censoring was non-informative.
Censoring is non-informative if it is independent of the occurrence of
an event. This means patients'
withdrawals should be at random and should not be caused by deterioration n the
health condition of a patient. It is
essential to notice that the fundamental for the survival analysis assumption
of non-informative censoring may not be satisfied for this study. The even free time of some patients was
censored due to worsening of their health status.
Therefore,
the censoring may be informative. This
means it may not be independent of the occurrence of an event. Now, let us assume that the before mentioned
assumptions are valid and we can take a closer look at the event rate changes. Changes over time of the event rate are
given in this table. The smallest
differences, one to two percent, is an event rate between the two groups occur
during the first several days and around 200 days after randomization, and the
largest difference, 10 percent, took place about 400 days.
Under
our temporary assumptions the results of statistical analysis are as
follows. Survivor functions for the
CRT-D and OPT groups are different at significant level 0.025 based on the
Wilcoxin test which is more appropriate than log rank test in this
situation. The Cox proportional hazard
model supplies the hazard ratio equal 0.81, at significant level 0.015. It is worth noting that hazard functions
clause and Schoenfeld residuals may not support proportionality assumption
which is essential for the Cox model.
Therefore,
the claim that CRT-D therapy reduces the relative risk about 20 percent is
questionable. The results of the
statistical analysis for the primary effectiveness end point may be problematic
because the primary effectiveness end point definition was changed during the
study. The assumptions on the line
statistical models use may not be satisfied.
The censoring mechanics applied may not be independent on the occurrence
of the end point. The censoring was
probably informative.
The
hazard functions and the Schoenfeld residuals suggest that the proportionality
assumption which is essential for the Cox model, may not be valid in this
case. Statistical analysis for
"all-cause" mortality secondary end point raises similar statistical
concerns as the primary effectiveness end point analysis and will be discussed
here shortly. Let us now assume that
the censoring is non-informative. We
can use the Kaplan-Meier method to estimate the survival function for the two
groups. The effect of CRT-D therapy on
the "all-cause" mortality is presented in this figure. The plus show that the estimated survival
functions are different and the survivor function for the CRT-D group is almost
always greater than or equal to the one for the OPT group.
Please
pay attention to the scale on the vertical axis. In this figure, the scale is the same as in the figures for the
primary effectiveness end point. In the
next figure, the scale on the vertical axis was changed and confidence
intervals for the Kaplan-Meier survival functions were added. The black curves are the survival functions
shown in the previous slide. The red
lines are the upper and lower confidence limits of the survivor functions for
the OPT group, while the blue ones are for the CRT-D group. The confidence intervals for the survivor
functions are crossing each other and even crossing the CRT-D survivor function
itself.
Changes
of the death rate over time by treatment groups are shown in this table. During the first 150 days after
randomization, the differences in death rates between the two groups are small,
maximum two percent, however, at 400 days, death rates for the CRT-D and OPT
groups were 12 and 22 percent respectively, so therefore there is a difference
in the survivor at 400 days is about nine percent in favor of the CRT-D
group.
In
the case of "all-cause" mortality and the tentative assumptions, survivor functions for the CRT-D and
OPT groups are different at significant level 0.003. The Cox model supplied the hazard ratio 0.64 at significant level
0.003. But for the
"all-cause" mortality, again, the statistical results may be
problematic because the assumptions underlying the statistical methods used may
not be satisfied. Hazard functions and
the Schoenfeld residuals do not
reasonably support the proportionality assumptions that is essential for
the Cox model.
Now
let us discuss the cardiac morbidity.
Sponsor considered only cardiac morbidity events which occurred in
hospitals but some events could and did take place outside hospitals. The hospital cardiac deaths is only a part
of the cardiac morbidity. There were
five cardiac deaths in the CRT-D group and three cardiac deaths in the OPT
group during the first 30 days after randomization; whereas, numbers of only
hospital deaths was zero and two respectively.
This is shown in this table.
Therefore, cardiac morbidity based only on hospitalization data that was
used by the sponsor does not supply the full information on all cardiac
morbidity events.
Adverse
events were defined by the sponsor as undesirable clinical outcomes and
included device related events as well as events related to the patient's
general condition. This table presents
the over times summary of all adverse events through six months. We can observe that over time the number of
events increases rapidly. During
additional 120 days, the numbers are double in the two groups. Assuming that each was to follow up patient
before the six months was free, the adverse event rates were 3.21 and 2.05 for
CRT-D and OPT groups respectively.
Using
the worst case scenario, the adverse event rate through six months was 3.73 for
the CRT-D arm while the similar rate for the OPT group was 2.80. According to both, the worst case and best
scenario analysis, the OPT patients experienced fewer adverse events during six
months after randomization. It is worth
noting that the validity of sponsor statistical analysis is of concern since
correlation between multi-events within a patient was ignored. Time of an adverse event occurrence was not
taken into account. Many follow-up
patients were excluded. Therefore, all
exploratory analysis should be interpreted with caution.
The
statistical review conclusions are as follows: treatment comparisons for the
primary effectiveness and mortality end points should be interpreted with
caution because of changes of "all-cause" hospitalization
definitions, withdrawals not clearly independent of outcome, and open label and
design. All cardiac morbidity events
that occurred outside hospitals were not taken into account. Lost follow-up patients, correlation within
a patient and times of the events occurrence were not included in the sponsor's
statistical analysis of cardiac morbidity and averse events. Thank you for your attention. Now, Dr. Proestel will present clinical
review of the study.
DR.
PROESTEL: Hello, thank you. I am Scott Proestel. I'm the Medical Officer at the US Food and
Drug Administration. For my
presentation, I will very briefly
summarize COMPANION design, issues surrounding the primary end point and
secondary end points, some additional FDA efficacy analysis that were performed
as well as a safety analysis.
We've
already reviewed the COMPANION trial quite well, I believe, so I will skip
through a number of slides. And I think
you're familiar with this as well. This
describes the primary and secondary end points. As you know, the primary end point was timed to
"all-cause" mortality plus "all-cause"
hospitalization. The secondary end
points for the trial are listed as well.
The results have been quite well reviewed as well. Just briefly 1638 patients were enrolled,
93 percent were randomized. Enrollment
occurred between January 2000 and November 2002.
As
you can see on the slide, those are the numbers of patients that were
ultimately enrolled in each cohort.
Here are the baseline characteristics for the three cohorts. In particular, I'd certainly like to focus
on the CRT-D and the OPT cohorts. Two
things that I would like to mention is that within the cohorts, there was a
modestly higher proportion of Class IV and ischemic patients in the OPT
arm. Mortality in Class IV patients was
2.9 times higher than in Class III patients and 1.7 times higher in ischemic
patients than in non-ischemic.
Therefore, both of these imbalances favor the device arm.
This
slide provides additional baseline characteristics which appear to be
well-matched. One thing I'd like to say
as well is that my presentation will provide only descriptive statistics and
should be considered adjunctive to the statistical findings discussed by Dr.
Krasnicka. All events from
randomization until patient withdrawal or November 30th, 2002 are
included. This is the primary end point
that was specified in the protocol which I believe you're all familiar at this
point.
However,
the definition changed three times during the trial. The definition initially was changed in March 2001 to include
only hospitalizations lasting greater than 24 hours. This definition changed again in February 2002 to include only
hospitalizations for which the discharge date deferred from the admission
date. Regarding the infusion
requirement, there was no required duration specified in the protocol, although
a duration of greater than four hours was ultimately used in the analysis.
As
the sponsor has provided case report forms from the beginning of the trial that
also specified this greater than four-hour time requirement, it appears that
this last change to the definition did not occur during the trial. A compelling explanation for the change in
definition would have been that the new definition is inherent to the old;
meaning that to be hospitalized necessarily means staying in the hospital
overnight. However, this is not the
case.
First,
if this were true, the revisions would not have been necessary. Second, the trial temporarily used a
different definition, meaning requiring that a hospitalization be greater than
24 hours in duration. Finally, I have
only a decade of experience in clinical medicine, but during that time I have
hospitalized patients for less than 24 hours and for less than an overnight
stay so can state with certainty that neither requirement is inherent to being
hospitalized. So far from adding
clarity, the requirement of a minimum
duration makes the definition more complicated. After all, to establish the duration of hospitalization, one
needs an admission order and a discharge order. However, to abide by the pre-specified definition of the primary
end point, one only needs the admission order.
If
the intent was to require a hospitalization of a certain duration, one would
argue that it should have been stated up front. So what was the ultimate definition of the primary end
point? While this is a busy slide that
is somewhat the point, the definition was considerably more narrow than the
encompassing claim of "all-cause" mortality plus
"all-cause" hospitalization.
So as can be seen, the hospitalization had to be associated with a date
change, could not be a hospitalization associated with an implant or a repeat
attempt at implant and could not be considered elective and associated with the
device. In addition, events that were
not hospitalizations were considered as such for the purpose of the primary end
point.
Getting
back to the issue of the changes that occurred to the primary end point, the
first question one could ask is whether the new primary end point is clinically
important. I think that the answer is,
is yes and in fact, it is likely more important than the original version due
to the requirement for a longer hospitalization. However, the next question that must be asked is, do the changes
that occurred in the primary end point undermine our belief in the observed
effect?
This
is a concern for FDA because if the primary end point is modified in response
to events occurring during the trial, this would allow for the possibility of
modifying the end point in such as way as to favor the device arm. This is one of the issues that FDA will ask
the panel to address.
This
slide presents data related to "all-cause" mortality which was a
secondary end point. In addition, all
cardiac death and the sub-groups of pump failure deaths and sudden cardiac
death are provided. This table presents
all deaths during the trial, including those that may have occurred following
subject withdrawal if that data was available and is presented in terms of
death per 100 patient years of follow-up.
The CRT-D arm is associated with a reduction not only in sudden cardiac
death and pump failure death but in cardiac death overall and
"all-cause" mortality. There
has been some concern in the public that the CRT aspect of the device, of the
CRT-D device, might be associated with an increase in sudden cardiac
death. However, as can be seen here,
the improvement in pump failure death overwhelms the modest increase in sudden
cardiac death leading to an improvement in cardiac death and "all-cause"
mortality associated with the CRT intervention.
So
solely for the purposes of understanding the CRT aspect of the CRT-D device,
these point estimates might be considered reassuring. Cardiac morbidity was another secondary end point. It was defined as the occurrence of the
following events listed on this slide and I believe this has been addressed
before, so I won't read them to you.
These events were also considered cardiac morbid events.
However,
the definition that was used did not match the definition provided in the
protocol. The definition that was used
for cardiac morbidity was any hospitalization during which one of these
specified cardiac morbid events occurred.
Therefore, a single hospitalization that had multiple cardiac morbid
events would only count once towards the end point. Using this definition, as you can see, there was a mean of 0.5
events per year in the CRT-D arm and 1.0 events per year on the OPT arm. The FDA does not have the data to calculate
the original cardiac morbid end point as specified in the protocol.
I
would like now to discuss some additional analysis that were performed for the
purposes of device labeling which may help to clarify the results of the
study. These were not specified end
points for the trial. This may, in some
way, address a concern that Dr. Brinker had discussed. As the primary end point only counted the
time to first event, any subsequent hospitalizations were not counted. Therefore, FDA felt it would be informative
to perform an additional calculation, the "all-cause" hospitalization
rate which was not specified in the protocol.
In this evaluation of hospitalizations for any cause, which included
implant attempt hospitalization, there was a mean of two hospitalizations per
year in the CRT-D arm and 1.6 hospitalizations per year in the OPT arm.
In
addition, the CRT-D patients were in the hospital for a mean of 11 days during
the year and in the OPT arm 10.7 days per year. There have been arguments made as to why it might not be
reasonable or appropriate to include the implant attempt hospitalizations in an
"all-cause" hospitalization analysis which I would like to now
address.
It
has been argued that the implant hospitalization is a single non-recurring
event. It is not. Forty-nine of the patients had to undergo
two implant hospitalizations and two patients underwent three. And in approximately four to six years the
device subjects would need to be hospitalized again to have the device replaced
due to battery depletion. Even if one
believes that the implant hospitalizations were recurring but at a trivial
rate, the rate was certainly greater than that for say cholecystectomy which
was included as a hospitalization during the study and luckily occurs no more
than once in a lifetime.
The
fact of the matter is that each of the causes of hospitalization is occurring
at a given rate and the implant attempt hospitalization is not even the one
associated with the lowest rate, so why exclude it. It has also been argued that the -- including the implant attempt
does not characterize the effect of the device. This is true and this is the point. The encompassing claim of "all-cause" hospitalization
by its very nature includes events that may not be tightly linked or linked at
all to the action of the device. Indeed
elective hospitalizations were included as events that counted towards the
primary end point, so once again, why exclude implant attempts?
Finally,
even if one decides to ignore implant hospitalizations, it may be worth noting
that the effect of the device on hospitalization was not of sufficient
magnitude during the trial to account for the implant hospitalizations that
were required to get the device. I
would like to emphasize that FDA is not advocating a change in the primary end
point. We are merely attempting to make
the case that this additional analysis of "all-cause" hospitalization
is reasonable, clinically relevant and may aid patients and physicians in their
understanding of what may be expected with this device therapy.
This
slide provides the FDA analysis of the implant hospitalizations which was
considered important to characterize despite not being an end point of the
trial. As can be seen, 541 patients had
a successful implant, 47 has unsuccessful implant and seven were randomized to
CRT-D but never underwent a procedure.
The mean duration of hospitalization was 2.9 days.
With
respect to safety, FDA reviewed all adverse events during the trial. These were defined as undesirable clinical
outcomes, including device related events as well as events related to a
patient's general condition. The first
set of numbers provides the total number of adverse events, not adjusting for
the larger number of subjects in the CRT-D arm and the moderately longer
follow-up in that arm. The rates adjust
for these issues and you can see that the device arm had a greater rate of
adverse events. However, the adverse
events in the device arm were not of a rate or severity beyond that which might
be expected for the intervention.
Indeed,
as can be seen in this slide, the proportion of adverse events that were
complications was actually lower in the device arm. An observation was defined as a clinical adverse event that was
correctable by non-invasive measures and a complication defined as a clinical
adverse even which required invasive measures to correct. Therefore, complications on average are more
likely to be significant adverse events.
And it is reassuring that the proportion of adverse events that were
complications was, in fact, lower in the CRT-D cohort.
What
I would like to do now is let Dr. Owen Faris present conclusions for the FDA
presentation. Thank you.
DR.
FARIS: In summary, FDA's review covered
the following areas; COMPANION primary and secondary implant results, COMPANION
hospitalizations and adverse events, consistency with pre-specified clinical
and statistical plans and presentation of the data on device labeling. With regards to the primary end point,
modifications were made to the hospitalization definition, part of the primary
end point, during the course of the COMPANION trial. Fundamental statistical assumptions underlying some analyses may
not have been met. Where the COMPANION
demonstrated a benefit, the primary end point as originally defined is
unknown. FDA requests guidance from the
panel in interpreting the modified primary end point.
With
regards to the secondary end point of mortality, the CRT-D device was
associated with a decrease in "all-cause" mortality compared to
OPT. However, fundamental statistical
assumptions underlying parts of the analysis may not have been met. Since the pre-specified statistical plan
required consistency between the primary and secondary end points, FDA requests
guidance from the panel in assessing the impact of modifications to the primary
end point on interpretation of the mortality benefit.
With
regards to additional concerns raised by FDA's review, the sponsor's analyses
included data obtained from patients after withdrawal. When implant hospitalizations were included,
the CRT-D device was associated with an increase in "all-cause"
hospitalizations compared to OPT. The
CRT-D device was associated with an increase in adverse events compared to
OPT. FDA requests guidance from the
panel in determining how these considerations should impact the sponsor's CRT-D
labeling.
Thank
you very much.
ACTING
CHAIR LASKEY: Thank you. Panel members? Dr. Normand.
DR.
NORMAND: I just want to beat a dead
horse again, but I need to get some clarification on the definition of
"all-cause" mortality. So
just to state it in my understanding of what's been presented, it is my
understanding that the initial protocol stated "all-cause" mortality
and didn't -- I guess didn't give a time frame for it. Is that correct?
DR.
PROESTEL: The definition for death
remained constant throughout the trial.
DR.
NORMAND: Okay, but it was just -- it
said, I'm sorry, "all-cause" hospitalization was just
"all-cause" hospitalization.
There was no timeframe of the "all-cause" hospitalization.
DR.
PROESTEL: Not in the protocol.
DR.
NORMAND: Not in the protocol. So that -- no one pushed for a
definition. One just said, okay,
"all-cause" hospitalization.
DR.
PROESTEL: With the caveats of the
greater than four hours of IV infusion and that the implant attempt would not
be counted. Beyond that, it was
"all-cause" hospitalization including elective hospitalizations.
DR.
NORMAND: Okay, and another point of
clarification. It's indicated that the
definition changed three times.
Hospitalizations greater than 24 hours and then the next one was a
hospital in which a calendar date it
was apparent. It seems to me for the
first to be true, the second has to be true.
Anything greater than 24 hours by definition the calendar date has to
change.
DR.
PROESTEL: Right, correct.
DR.
NORMAND: So if my understanding is
correct and I may be wrong about this, if you're going with the greater than 24
hours, then indeed, using the second definition, hospitalizations for which
there was a calendar date change, you could actually include patients that were
hospitalized for less than 24 hours, correct?
DR.
PROESTEL: Correct.
DR.
NORMAND: Okay, and then my last just
clarification, help me think through some things. It is, I think you indicated that there was -- there were
revisions but I heard a little bit earlier that there was never a revision of
the data collection form. Did you mean
revisions to the numbers that reported to FDA or did you mean revisions to the
data collection instrument?
DR.
PROESTEL: Revisions to the primary end
point, I mean, you can collect data on a case report form that is not
necessarily -- in fact, most of the data on the case report form is not related
to the primary end point. So the fact
that that data is on the case report form, certainly does not mean that the
primary end point was, in fact, a date change or 24 hours. It should have
been what was stated in the protocol.
DR.
NORMAND: Thank you very much.
ACTING
CHAIR LASKEY: All right, next? Yeah.
DR.
KRUCOFF: Dr. Krasnicka, I'm going to
ask you for help because -- and I want to talk just about mortality, okay,
death. Your contention that I'm just
going to need some education on, I guess, about the underlying assumptions for
the Cox model.
DR.
KRASNICKA: Yes.
DR.
KRUCOFF: Does that effect the mortality
reports and effect of the device on mortality in this model?
DR.
KRASNICKA: Yes. This means -- the second part, the sponsor
plan is that there is 66 percent of reduction in related risk if the assumption
is not -- we don't know exactly, again, because it's really this estimation is
biased.
DR.
KRUCOFF: So to the relative lay person,
can you help me understand what's bad about this?
DR.
KRASNICKA: I can show you Schoenfeld
residuals and you can see how this estimation is change over time. It's from the plus to minus and this is
mortality -- slide. The next one. And you can --
DR.
KRUCOFF: Would you mind getting closer
to the mike, I can barely hear you.
DR.
KRASNICKA: You can see that the
coefficients at treatment in Cox model is changing from the plus to minus and
then to plus. This means that the
proportionality assumption is not true of the Cox model and we cannot claim,
for example, that there is 66 percent of the reduction in related risk.
DR.
NORMAND: Perhaps if I could -- if I
could maybe just ask a question to perhaps clarify the answer. I guess part of the panel members are
wondering if the Cox -- if you use a Cox model to analyze the data, and you
reported an estimate based on a Cox model in which the proportionality
assumption is violated, I think that's what you're suggesting.
DR.
KRASNICKA: Yes.
DR.
NORMAND: The Cox model, that the
proportionality assumption was violated, in which case it says that they cross
and you wouldn't want to say that it, indeed, was a -- you know, one way or the
other. They crossed and so sometimes
it's good and sometimes it's bad. Is
that a fair characterization of what you're --
DR.
KRASNICKA: Yes, yes.
DR.
KRUCOFF: Okay, so to my mind, when I
look at this, what I see is that, in fact, the relative benefit to death rate
over time in a population treated and not treated with the device, may be
different at different times --
DR.
KRASNICKA: Yes, yes.
DR.
KRUCOFF: -- along the time.
DR.
KRASNICKA: Yes.
DR.
KRUCOFF: It's not uniformally
beneficial.
DR.
KRASNICKA: Yes.
DR.
KRUCOFF: But how much impact does that
then have on the end conclusion or inability to reach a conclusion that at the
end of 300 days or a fixed time period that ultimately in a population who has
some heterogeneity through a range of mechanisms that may behave differently at
different times, that at the end of a prolonged observation, you could make a
wrong claim.
DR.
KRASNICKA: The best way it would be
adjusted for the baseline providers and to check if, for example, the models
are correct, are good for this case, and to check for example, how centers have
impact on the result because in the case of the survival analysis, really you
have to adjust for the covariance to get not bias estimation of the
treatment. It's completely
different. For example, in the case of
binary outcome, at one year, you don't need, really to adjust for the covariance. That --
DR.
KRUCOFF: So has anybody done that? Have you guys done that? Can anybody show us any adjustments?
DR.
KRASNICKA: No, I got that set only for
really two, three weeks and I didn't have time.
DR.
KRUCOFF: All right, one other
clarification question and I'm done.
We've obviously heard clearly that there's a concern about whether the
censoring process was informative.
DR.
KRASNICKA: Yes.
DR.
KRUCOFF: But as I understand it, at
least, if it is, if basically patients who in the OPT arm, were getting sicker
so they got pulled so they could not be a violation, go and get their device
through other means, if the presumption is those patients were getting sicker
and they are withdrawn, doesn't that -- isn't that actually unfavorable for the
device?
DR.
KRASNICKA: Yes, but when you look at
the "all-cause" hospitalization definition, definition was changed
and really all hospitalization for any reason was dropped and when I was
thinking that maybe the patients from the CRT-D group got problem with device,
and for example, went to hospital for one, two hours, so we don't know really,
what's happened with the primary effectiveness end point.
DR.
KRUCOFF: Okay, I understand the
definition got changed, but I think this is going to be really important. To me, are you saying that there's some
relationship in your mind? Are you guys
thinking that the change in the definition of "all-cause"
hospitalization somehow relates to an informed or biased censoring or
withdrawal of patients from the OPT group?
Or are these separate issues?
DR.
KRASNICKA: Separate issue.
DR.
KRUCOFF: They're separate issues. So all I was asking is, on the informed --
on the concern about informative censor.
That's all I was asking --
DR.
KRASNICKA: Yes, okay.
DR.
KRUCOFF: -- is if I understand the
concern, which is a real concern, at least the way I see that one issue, it's
actually unfavorable to the device if patients who are getting sick are in the
control -- the in OPT arm, are getting dropped out --
DR.
KRASNICKA: Yes.
DR.
KRUCOFF: -- that would be unfavorable
for the device. Is that not true --
DR.
KRASNICKA: Yes, could be.
DR.
KRUCOFF: -- in terms of claiming a
benefit for the device?
DR.
NORMAND: I think you could make
arguments along a number of different directions on that. I just feel I have to say this.
DR.
KRUCOFF: I'm just asking a question.
DR.
NORMAND: No, and I'll give you at least
my opinion on that. And that is if --
certainly one could argue that they could be healthier, there's no doubt about
that, but one sicker -- but only may say they're healthy enough to receive the
device, so there is some selection. So
you could in some ways argue about them, yes, maybe they were sick enough to
get the device, but yet, they had to be healthy enough to actually receive the
device in the absence of this. So there
is a selection process in there that does raise a concern -- not raise a
concern but --
DR.
KRUCOFF: But assignment to the device
was randomized.
DR.
NORMAND: Well, no, you're saying there
are a group of people -- I'm asking a hypothetical question, so there's a
hypothetical question where someone was randomized to treatment one or
treatment two. I'm saying it
hypothetically because I don't want to -- I don't know the answer to this in
this particular situation but if they were randomized to treatment one or
treatment two and another therapy becomes available and someone says,
"Gee, I want to get it, I want to pull out of this and get this",
there are considerations that say, "Yeah, I recommend you actually do
that".
And,
yes, they may be sick enough to need the new device but often there are
patients that get devices that are healthier, because they're robust enough to
actually get the device rather than the physician saying, "No, stay on the
current treatment". So you could
argue both ways.
DR.
SOMBERG: But the trouble with that is
it sort of addresses the question that Dr. Proestel showed me that there was
really no major inflection point in the -- in the data because that would
occurred during the course of the trial when these devices became available and
there wasn't a change in the number of patients who were in the pharmacologic
therapy were then being censored from the study. Am I correct in that?
DR.
NORMAND: I'm not sure about the answer
to that question but I am sure about the answer to the question that it's not
necessarily true that it would have favored the therapy arm if some people
left. I can't conjecture on why there
wasn't because normally you see a big jump.
DR.
KRUCOFF: I'm sorry, I lied. I have one other quick clarification, Scott,
at least because it's on the record. In your slide, showing the baseline
characteristics, I just want to make sure that I heard what you said versus
what I see. The Class III, Class IV
ischemic population, Class IV population slightly higher incidents in the CRT-D
arm, than in the --
DR.
PROESTEL: The ischemic and the Class
IVS were --
DR.
KRUCOFF: Were higher in the OPT than in
the CRT --
DR.
PROESTEL: Right.
DR.
KRUCOFF: Okay.
DR.
PROESTEL: Did I say that the other way?
DR.
KRUCOFF: I'm not sure what I heard or
what you said.
DR.
PROESTEL: Okay.
ACTING
CHAIR LASKEY: All right, this is not a
rhetorical question. For this
statistician again, my -- when I look at the data presented by the sponsor in
these figures, these blocks, the survival curves. There are two pieces of data reported here. The first is the log rank statistic that
compares the two survival curves which is the standard way to do product limit
survival analysis. And then there's
this hazard ratio which comes out of another analysis. Is that correct?
DR.
KRASNICKA: Yes, yes, correct.
ACTING
CHAIR LASKEY: That comes out of a Cox
proportional hazards regression.
DR.
KRASNICKA: Yes.
ACTING
CHAIR LASKEY: And that's a different
set of statistics than the standard product limit Kaplan-Meier set of
statistics. And that's I think, part of
the confusion up here, is that on one plot both of these, quote
"results" are being reported and yet, the problem you're having with
the Cox proportional hazards has been well articulated but it's -- I guess the
other issue is how we interpret the Kaplan-Meier curves and I guess we'll come
back to that this afternoon, but there's two separate analyses going on here.
DR.
KRASNICKA: Yes. Completely separate.
ACTING
CHAIR LASKEY: Yeah. Thank you.
Dr. Somberg, are you not hungry?
DR.
SOMBERG: No, not really. I'm on Central Time, remember that. It's not lunch time yet. I'll make it very quick. Number one, I'm going to play devil's advocate
for a moment here and the -- while there's debate whether the four-hour
infusion was to be counted or not between what we heard of the sponsor's
presentation or the academic investigator's, I should say, presentation, and
the FDA. Let me ask you, does it really
matter, because it only contributed, I think we said four percent?
DR.
PROESTEL: Well, basically, we are
cataloging the changes to the end point.
In fact, the case report form originally was designed to capture greater
than four hours from the beginning of the trial, so I don't see that as a
problem. I do think that the other two
changes to the primary end point are concerning because they occurred during
the trial.
DR.
SOMBERG: Okay, I hear you, and my other
next question is the study withdrawals, that was a very high number, 20, 25
percent and that's what really got the investigators to decide to go back and
to reconsent and to go through it. I
was very impressed how thorough that was but I understand that comment was made
that there's a question of the reliability, that it may be unreliable and may
have added a bias into a blind. I mean,
isn't that to be commended, to go back and to look at it. If we left that 25 percent and we found that
20 percent difference, then we would have said, "Hey, look, that could
have contributed, but now we've gone back.
It was reduced to next to nothing and why is there a bias, why is it
unreliable?
DR.
PROESTEL: Well, there's a number of
issues. One is there is an -- if you
allow -- that would be, I guess, the fifth change or well, maybe the fourth
change. You know, there should be some
limit on the number of ways one can reinterpret the design of the trial. And while I certainly agree that this
additional information is valuable, I think it's worth considering that the
original specified plan should also be presented with that data and this would
be adjunctive data that could be included.
Another
issue, as far as the reliability, I'm
going to try and find a piece of paper.
It provides the description the sponsor provided for what was done. You can chat amongst yourselves.
ACTING
CHAIR LASKEY: While we're doing that,
is Dr. Waldo still with us?
DR.
WALDO: Yes, I am.
ACTING
CHAIR LASKEY: Great. Did you have any queries for the FDA?
DR.
WALDO: I mean, I think this whole
discussion of the statistics is critical.
I share with my colleagues, I'm not a statistician and I think I have to
tell you honestly, when I first read this, I -- my tilt button went off because
of all the numerous changes. I mean,
the first change was well over a year after into the trial. The second change was still a year
later. I mean, that just bothered me
but again, I have to rely on my statistical colleagues to say if that's --
something which is intuitive has merit in terms of my being upset. I just think that was really bad.
Of
course, I mean, you -- and this -- and we kept hearing that this was -- all
previous trials had done it this way.
Why didn't they design it that way from the beginning? I think that was a problem. And I think I need some more statistical
help.
The
other thing that bothered me was that some of the adverse -- some of the things
with the implantation of the pacemakers were considered as adverse events
because of the way that they were -- with the revised definition. So in other words, if you had a revised lead
or something like that and you didn't have to stay overnight in the hospital,
that was just an adverse event and it didn't require hospitalization, the
reason that really bothers me, again, I notice, I think I heard there weren't
that many revisions but I don't know how many other things there were, but what
bothers me about that, is that really we've heard over and over again from both
the presenters and from the FDA analysis that this whole thing was driven by
hospitalizations, I thought 90 percent roughly I think is right, of the events,
so hospitalization, I think, is really critical.
And
I share a lot of the concerns about how you consider hospitalization because
the hospitalization is the reason that you reach the end point in this trial
and you make conclusions. So if you
just give devices a buy as they seem to have done, I don't think that's valid. It just doesn't make any sense to me. It doesn't make economic sense. I think when you consider all things with
patients, they have to understand that you know, that the hospitalization is
part of this. So that bothers me also
because it's hospitalization driven.
In
fact, I'd be honest with you. I was thinking
that if I were designing this trial and I'm an electrician and not a plumber,
but I would have thought that mortality was a critical part of this and it's
not the major driver of the primary end point.
And I was even asking -- well, so I'm saying a lot of things. I have two other points. I'm saying too many things before lunch, I
think, but I have read many, many times the approved indication and the request
for change that Guidant is asking for and I have difficulty sorting out the
difference. So, I mean, that's even a
more fundamental question for me. What
are we here to talk about, because I haven't appreciated the difference between
the approval that I understand they have and the change that they're asking
for. So that many -- and I have a few
other things listed by maybe that's enough to start for now.
ACTING
CHAIR LASKEY: Right, we'll come around
to general critique comments this afternoon, but I just wondered whether you
had any questions for the three FDA presenters but --
DR.
WALDO: Well, I only worry about that my
relative unsophistication in understanding statistics and I respect the
statisticians and I know Dr. DeMets, too, and I think he's a well-respected
person, so I wish that the two groups of statisticians could maybe come to some
understanding or do we understand there are disagreements between them because
I'm not sophisticated enough to challenge one or the other. I do very much worry about all of these
hospitalization changes and in a the study driven by hospitalization where
that's really what has driven all -- virtually all the conclusions in this
trial, that this seems very messy and very worrisome to me.
ACTING
CHAIR LASKEY: All right, well, rest
assured we'll try and get some consensus for you this afternoon. Thank you, Dr. Waldo. We'll get --
DR.
WALDO: Sorry, I couldn't be there. I got to Baltimore, but the plane wouldn't
land.
DR.
PROESTEL: I'm sorry, just to follow up,
we had discussed this issue with Guidant and they provided a response. It's a withdrawn patient consent process and
I'd like to just read a portion of this so that you might understand our
concern. "Guidant determined that
if patients did not withdraw their consent at the time of discontinuation in
the trial, they would not require reconsent.
Rather they would be covered by the original study consent if the
coordinator was aware of the patient's status and did not require consulting
the family or medical records. A second
letter was sent to the principal investigators on March 6th, 2003 clarifying
this information. A copy of this letter
is attached for reference".
This
letter cites, "to review their patient's consent status from the patient
device status form attached, if the withdrawal reason selected was either 13,
patient refused follow-up or possibly 88 other if explanation given indicates
consent was withdrawn. The situation
would require reconsent with the additional informed consent as outlined in the
February 20th, 2003 letter". This
is the important part. "All other
reasons for withdrawal would allow the research coordinator to fill out
required CRFs including withdrawal contact and treatment modification if
patient received his device if data was known without contacting the patient,
family or medical records".
So
to me this indicated that data was being filled in to CRFs based on memory
which I think is unreliable.
DR.
SOMBERG: I mean, I hear what you're
saying but I'm not sure that states that.
It says that they would fill out the CRFs if they didn't feel that it
required a secondary consent form filling because of those two issues. If a data coordinator fills out a CRF, and
we can ask the group here that monitored the studies, they would have to go
back to the source records. I mean, I
do investigations all the time and my brain is zilch for remembering what
happened yesterday in terms of all sorts of things because you hear a constant
in-flow of data so you go back to the source records. So I don't think there's that implication there because I think
that goes to the heart of the matter is the changes and, you know, I grant you there may be, and we can have a
debate on this and all that but if there were changes, does it increase the
unreliability and I thought going back and reconsenting and going down to only
about four patients that were not in the data base was a remarkable success
from a potential failure of having 20, 25 percent not filled in. So I think we should go back after maybe
lunch and see if it was just on guesstimates on what the data was or the data
coordinators were actually instructed at each site to use source records and
did they not get monitored and have the source records checked.
ACTING
CHAIR LASKEY: I don't. So do we have access to that, what you just
read? Maybe you could make some copies
for us. It's somewhat at odds with what
Dr. Bristow described the process as being, so it would just be helpful. I'm really suggesting that we break for
lunch at this point. I have 12:40. Let us regroup at 1:40 and we'll
resume. Thank you very much.
(Whereupon
at 12:40 p.m. a luncheon recess was taken.)
A-F-T-E-R-N-O-O-N S-E-S-S-I-O-N
(1:45 p.m.)
ACTING
CHAIR LASKEY: All right, people, thank
you for coming back on schedule. It
being 1:45, I'd like to resume and before we have our lead reviewer give his
review, the FDA had one more point to clarify something that came up during our
conversation with Dr. Waldo.
DR.
FARIS: FDA would just like to offer
clarification on one important point that was raised. Dr. Waldo asked a question about the significance of the
population change in the indication statement.
The sponsor's current indication requires that a patient meet the
specified heart failure criteria and also have a conventional indications for
and ICD. The sponsor is seeking removal
of the ICD indication requirement based on the COMPANION results.
DR.
WALDO: Thank you.
ACTING
CHAIR LASKEY: Welcome back, Dr. Waldo.
DR.
WALDO: Thank you.
ACTING
CHAIR LASKEY: All right, we'll start
out with Dr. Maisel giving his review.
Bill?
DR.
MAISEL: Thank you. Good afternoon. I will not review in detail any of the data that has been
eloquently presented by both the sponsor and the FDA and I think many of the
important issues have already been touched on.
I would like to focus on a few of the contentious issues which, in my
mind, include a few things. One is the
hospitalizations. Second are the
withdrawals. Third is the mortality end
points and then finally I'd like to talk about some of the safety issues. So I will start with the hospitalization
issue.
Just
as a point of clarification from the sponsor, I'm interested in understanding
exactly what it was that prompted the changed in definition of the
hospitalization end point. One quote I
heard this morning was to make verifiable data possible. So is it your position that the reason the
hospitalization end point was changed was so that the data could be interpreted
correctly that you were receiving in the case report forms? It's a yes or no question.
DR.
CARSON: The answer to that then is,
yes. The -- once again, to reiterate
and maybe I can just amplify this because it keeps coming up, maybe amplify a
little bit more what was said this morning, the -- for every trial in which
hospitalization has been used in heart failure as a primary or secondary end
point there's been a duration criteria.
The duration criteria has not always been stated in the protocol. It wasn't stated in the VALHeFT. It was stated in the MERIT Heart Failure
protocol but then the committee went to a calendar date change from a
24-hour. I'm sorry.
DR.
MAISEL: I understand -- you can stay
there. I understand a lot of those
issues and I don't want to rehash them.
What I'm trying to understand is, you also said that you felt that
events that were less than 24 hours in duration were, "exceedingly
rare". So I'm trying to understand
if you felt that those less than 24-hour hospitalization events were
exceedingly rare, why you felt so strongly about changing the primary end point
which obviously has led us to a great deal of --
DR.
CARSON: Discussion.
DR.
MAISEL: -- discussion.
DR.
CARSON: First of all, I would say from
my standpoint, the standpoint of the morbidity and mortality committee, on the
steering committee, the end point did not change. The end point committee, in a sense, finalized the criteria for
"all-cause" hospitalization by presenting a 24-hour barrier. That was, in part, because it had been done
in previous clinical trials to that time and also it represented a day in the
hospital and I think as everyone is pretty well aware, many hospitalization
systems define a hospitalization as being something over 23 hours.
Now,
what I said this morning was that a calendar date change, hospitalizations that
did not involve a calendar date change, I believe, are rare and a little
difficult to figure out what they would be.
So 24-hour -- less than 24-hour hospitalizations are not necessarily
rare. In fact, in this trial, and we
have a backup slide on this, I think about 16 percent of the patients in CRT-D
had a hospitalization for less than one -- than a 24-hour period. About 20 percent in CRT did. So there --
DR.
MAISEL: And what about OPT?
DR.
CARSON: I'm sorry, 20 percent in OPT
and 16 percent in CRT.
DR.
MAISEL: Okay. I guess, my point simply is that while it seems that your
intention was to make it easier to interpret the end point, I think you added a
great deal of confusion and I think the simple was the patient hospitalized or
not, while I understand the issues regarding whether that was the appropriate
end point to pick, it was picked and I don't agree with the position that you
clarified things by changing it. I
think it obviously, in my view would have been a lot easier just to count how
many people were hospitalized as was initially intended. And I'll give you a chance in a minute to
respond to that.
DR.
CARSON: Okay.
DR.
MAISEL: The other issue I had was I'm
trying to understand exactly when it was that hospitalizations were first
adjudicated. There's a statement in
Section 6-1 on page 4 that says, quote, "No hospitalizations were
adjudicated until the 6/23/01 meeting".
Is that accurate?
DR.
CARSON: That's incorrect. That's not correct.
DR.
MAISEL: Okay, so were they first
adjudicated in March 2001?
DR.
CARSON: The first adjudication meeting
was March 16th, 2001.
DR.
MAISEL: So is it fair to say that the
data was not analyzed or looked at until those events were adjudicated? What I'm trying to understand as well is
that in Section 5-4 on page 14, there is a graph of the DSMB analysis. And the first point where there is an
analysis is dated November 10th, 2000 and it says, "combined mortality and
hospitalization end point", and it has a Z statistic. So I'm trying to understand how they were
able to analyze the end point prior to any end point adjudication, if you could
clarify that for me.
DR.
CARSON: I think that would probably be
a question for -- one would say then that what they were looking at was
unadjudicated data for the primary outcome.
That would have been the only way that could have been done because we
did not meet until March 16th of `01.
That was the first time -- the first meeting we had and prior to the
start of that meeting and let me emphasize again, prior to any end point ever
being adjudicated, the 24-hour duration hospitalization was in place.
DR.
MAISEL: So the earlier discussion we
had this morning where it was stated that the data went to the M & M
committee and then back to the clinical research organization and then to the
statistician and then to the DMSB was not necessarily always the case.
DR.
CARSON: Well, the adjudicated forms,
the adjudication data, would have gone to the M & M committee. The adjudication data would have been
adjudicated by us. Whether there was
another communication of unadjudicated data, maybe Dr. DeMets could tell.
DR.
DeMETS: Yeah, the thing is quite common
in monitoring trials and groups like mine.
It would be reports for
monitoring, that is you take what you have, the best most up to date data you
have, so at that point in time, you're correct M & M committee would not
have met but we clearly had data on unadjudicated events, mortality and so you
typically present the best data you have, which is a mixture along the way of
adjudicated, unadjudicated, at that point in time was all unadjudicated, and as
they move along, you have a mixture of adjudicated events and plus the
non-adjudicated and then you'll probably -- we always do, at least at our place,
provide a table which has got the adjudicated, but that's always behind.
So
while it's adjudicated, it's old news.
So -- but we were looking at what the team was looking at which we
reported to them at that point in time would have been unadjudicated, but they
would have seen that or known that.
DR.
MAISEL: Right, but my obvious point is
that I'm concerned that there was statistical analysis that was performed prior
to the changing of the definition of hospitalization and if you look at the Z
statistic, it's in favor of the OPT group.
The Z statistic is minus 2.057.
If you go to Section 5-3, page 42, you show the DSMB same analysis for
"all-cause" mortality and the Z statistic favors the device. And so what that says to me is that the
negative Z statistic was strongly because of a large number of hospitalizations
in the device group. And so this was
known as of November 2000 and so it just begs the question of you know, five,
four months later now, there's a meeting to discuss changing the definition and
while I certainly understand and respect the statements that have been made
that there's no communication, et cetera, you know, on paper it seems that the
fact that there were a lot of hospitalizations in the CRT-D group early on, was
clear at the time of that, that the definition was changed.
DR.
CARSON: Could I just maybe help with
one comment here? Recall that what the
sites were being requested to send were events that from the original CRF that
had a date change. So, in fact, all of
those hospitalizations then would have come to the external CRO. There would not have been an additional
group of hospitalizations. Those
hospitalizations all then eventually came to us after they assembled with all
the clinical materials that would make it possible for us to have an opinion on
each case.
So
Dave, I think that would be --
MS.
WOOD: If I could interrupt for just a
minute, just a procedural issue, the tables should be left free. If you have a question to answer, please
come to the podium. That allows the
advisory committee to interface with both the FDA and the sponsor. Thank you.
DR.
DeMETS: I apologize for my lack of
protocol. Yes, there was no
communication. In fact, we followed
almost to the letter the current independent monitoring committee charter,
draft charter, that was issued in November 2001 to alleviate just the kind of
concerns that you are pondering. That
is by having an independent statistical center, an independent monitoring
committee, an independent M & M committee which did not communicate those
kind of concerns are to be addressed in that way. So that's why the FDA charter was written that way. That's why it's been conventional practice for
the past 30 years, I suppose. So there
was the communication to prevent those kind of issues being an issue.
DR.
MAISEL: Okay, thank you. It was also -- it was stated in the FDA
review but I'm not sure I saw it in the sponsor review, that it was not
possible to go back and analyze the data based on the initial definition of all
hospitalizations, recognizing that the implant hospitalization was not going to
be included. Is that an accurate
statement, that you do not have the data on "all-cause"
hospitalization putting aside the device implants? In other words, hospitalizations that were -- any
hospitalization, the original definition in the protocol.
DR.
CARSON: Well, there would be -- what we
don't have particularly from my standpoint, Dr. Bristow may have something to
add, but there is not data in which there was not -- the sites were asked to
report according to the case report form and that involved a calendar date
change. So there is -- there's not data
then on hospitalizations who did not meet any sort of duration criteria.
DR.
MAISEL: Because it was stated this
morning that -- and I believe it's on one of the forms that it says, quote,
"You must use this form for each hospitalization". So was that -- were you -- I mean, if I were
doing it, I would have tried to collect as much hospitalization data as
possible and then if you were going to narrow the scope, I understand that, but
it was stated this morning that the participants were asked to submit a form
for every hospitalization. Is that not
true? They were asked to adjudicate the
event themselves and only submit the form if there was a hospital date change
or they submitted a form for every hospitalization?
DR.
BRISTOW: Only if there was a hospital
date change did they submit a form. Let
me provide a little background here in terms of the "all-cause"
hospitalization notion so -- on June 17th, 1999, we met with the FDA about the
thoughts for this protocol and the concept was that we would be running a
clinical end point that would include hospitalization and death was a competing
risk. And some discussion took place
with the FDA regarding what that hospitalization would be.
Our
notion, and I'll give you some direct quotes here, I brought the wrong thing to
the podium, unfortunately. My direct
quote though was something like a real hospitalization in fact, DRG 127 for
heart failure and so our original notion was that we were going to run a
competing risk, primary end point of death and heart failure hospitalization or
at the least, cardiovascular hospitalization because this is the
hospitalization component that can be benefitted by an effective heart failure
treatment.
So
the idea was that we have a real hospitalization, not something where
somebody's blood pressure is found to be 120, not 60 or his INR is found to be
two, not seven and then gets discharged right away. This study would count real hospitalizations, DRG 127 including
heart failure. So right from the
beginning, the idea was to eliminate these trivial things that could happen,
use of hospitalization for short stay, for example, real hospitalization and
then the notion of "all-cause" actually came from the FDA.
They
said, "Well, fine, you know, measuring heart failure, cardiovascular
hospitalization is okay, but we want you to measure all real
hospitalizations. We want you to
capture the stuff that might be a fallout from device use and
implantation. Okay, if you have a
complication of a device requiring a hospitalization, subsequent
hospitalization, we want that captured".
And
so we agreed, "Okay, we'll do this". Now, this is not ordinarily done
in a heart failure clinical trial because you're dragging along a lot of
noise. In our case, about a third of
the total hospitalizations were non-cardiovascular and were not going to impact
favorably on that with a heart failure treatment, but because this was the
mandate from the FDA, this is where "all-cause" comes from. Spreading out the mode of hospitalization,
the cause specific aspect beyond cardiovascular or heart failure into non-cardiovascular,
it never met stuff that really isn't a hospitalization. It doesn't really require a hospitalization
and we can track this back historically.
So
of course, what happened in COMPANION is we had a much greater treatment effect
on cardiovascular hospitalization. In
fact, the hazard ratio is something like --
ACTING
CHAIR LASKEY: Thirty-six percent.
DR.
BRISTOW: No, it's not quite that. It's .72 and for heart failure
hospitalization, the hazard ratio is .6.
So the total comes from measuring non-cardiovascular hospitalizations.
DR.
MAISEL: I don't debate the well-meaning
or potentially even the appropriateness of the definition that you ultimately
ended up with. I think there are a
couple of important points. Number one
is a device trial is not the same as a heart failure pharmacologic trial
obviously. Number 2 is, I'm still a
little unclear as to why this conversation that took place in March 2001 didn't
take place in 1999 when the protocol was written and maybe you can shed some
light on that.
DR.
BRISTOW: Frankly, I guess I can take
some of the credit for this. The
steering committee and myself specifically, never thought this was a
substantive change. This is the
technical way the end points committee does its business and this is the way
that I have handled it as a steering committee member previously. We let the end points committee decide how
they're going to do things. They do
state of the art things. They tend to
be the same people from trial to trial and to me, this really never made any
difference. They had to use a system
that would allow them to have a verifiable real hospitalization in the spirit
of the protocol.
To
me this was technical detail as opposed to a substantive change in the primary
end point. That is the reason why we
didn't basically say, you know, "Sponsor, you've got to tell the FDA blah,
blah, blah". We just never thought
that this was anything substantive.
DR.
MAISEL: Okay, I'd like to shift gears a
little bit and talk a little bit about the withdrawals.
DR.
CARSON: Can I just answer one more
thing because you brought it up at the beginning of this question and that was
the fact that the end point duration was 24 hours and then it was a calendar
date change. I just wanted to
re-emphasize that this was done because the data that was being collected on
the case report form was a calendar date change. When the committee looked to try and pull out to verify that
these were 24-hour admissions when it was a single calendar date change, we
could not verifiably do that. And
that's why we made that switch.
DR.
MAISEL: Okay, thank you. It's been well-documented that the
withdrawal rate was much higher in the pharmacologic, the OPT group compared to
the CRT groups and I think we all recognize the reasons for those withdrawals
regarding implantation of CRT devices.
I guess I have a couple comments and then you can respond. Number one is, it seems obvious to me from
reading the instructions to investigators that that was going to result in a
large number of withdrawals, I think, forcing physicians to get approval to do
what is a medically indicated procedure in a patient, I think would
automatically result in withdrawal.
So
did you consider -- I mean, to be what I probably would have done was simply
given them very specific instructions about who could get a CRT device. Essentially, it seems to me that they were
-- physicians were forced to withdraw their patients if they wanted to do what
was right for their patient.
DR.
BRISTOW: Well, you have to understand
that the withdrawal rate began to go up when these devices became on the market
and then we sort of reacted to this emerging problem that we had. And you know, the truth of the fact is that
we had not proven that either of these devices works in this patient
population. And our position was that
if you're an investigator, you ought to have that report about the treatment in
your trial and this is unproven therapy and you really shouldn't be doing
this.
But,
yes, there comes a time and just for patient care, if you have an approved
something but there is what has to happen.
There really has to be deterioration and it has to be documented. We felt that was a reasonable way to do
things. So, what would happen, of
course, as has been mentioned earlier, you know, the patients that were
withdrawn probably were the ones getting sick.
And, of course, if they're withdrawn and we never find out the end
point, that's going to work against the device. On the other hand, we don't know -- as someone else mentioned, we
actually don't know how this is going to work out. So the ethical mandate is to go get all that data.
DR.
MAISEL: Yeah, I think you should be
commended for an extremely thorough and difficult job of filling in the blanks
for all those withdrawn patients and certainly had you not done that, I'm sure
we would have spent a lot of time discussing that today. I'm a little bit concerned about how the
missing data, particularly in the hospitalizations, what's filled in. There's some patient scenarios given in
Section 6-2 on page 4 and one example is that, you know, a patient is contacted
by phone and reports that they had not been hospitalized in the last whatever
it is, 18 or 19 months and that was accepted as, you know, data and an end
point, and I think we can all recognize the inherent unreliability in data like
that.
I'm
concerned about that, more for the hospitalization data than for the mortality
data. What efforts -- I think if a
patient -- well, maybe you can clarify for me.
If a patient denied being hospitalized, they got marked down as not
hospitalized and if they said they were hospitalized, the data was tracked
down; is that --
DR.
BRISTOW: Oh, yes, absolutely. I mean, the only risk from this, I believe
-- I mean, the same procedures were undertaken as for non-withdrawn patients
and the only risk here is that you would have under-reporting. You just wouldn't be able to get all the
events, in which case, that would lead to a lower event rate in the
disproportionate withdrawal group, which would be the OPT group. Again, the bias would be against the
device.
But
we -- I mean, the coordinators, investigators were instructed to go get these
data. They had to have source
documentation. This had to be
adjudicated, had to have the dossiers filled with all the source documentation
and so forth. So it was handled exactly
the same.
DR.
MAISEL: So, I guess to summarize my
position on the hospitalization, I would say I'm quite concerned about a number
of these issues, perhaps any one of which may have been possible to overlook
but the data analysis prior to the initial adjudication, the large number of
withdrawals, the unreliability of the data makes me concerned about
interpreting that end point as well as if you step back and ask the clinical
question, you have a patient in front of you.
You know, in my mind the initial hospitalization, while I certainly
recognize the goal to demonstrate efficacy of the device, taking a step back,
you know, if I have a patient in front of me and tell them that they're going
to be hospitalized, I think there's no conclusive evidence that that's the case
here.
DR.
BRISTOW: Well, another point is, it's
not just hospitalization that you're effecting, heart failure hospitalizations
primarily, but some other cardiovascular perhaps. With that goes improved quality of life, improved exercise
tolerance, all the stuff that relates to interrupting the cycle of progressive
heart failure. We haven't presented any
of that data because that was used for previous approval of the device. But it's not just the hospitalization, it's
everything that goes with progressive heart failure is benefited.
DR.
MAISEL: I completed agree with what you
just said. With regard to the mortality
end point, I'm comforted by the statistical analyses that have been presented
today. I think in the log rank or
Wilcoxin statistical evaluation whichever you prefer, both demonstrated in an
unadjusted analysis that mortality was improved in the CRT-D group. I recognize the shortcomings of the Cox
proportional hazards analysis but that also showed a benefit.
I'm
more comforted by the withdrawal analysis of mortality simply because I think
it's much easier to identify vital status.
So I do believe that these devices do result in improved survival and
decreased mortality.
DR.
BRISTOW: In regard to that, I certainly
agree with that comment. The original
protocol actually gave some guidance for going after patient's mortality data,
vital status data, who had withdrawn.
It was in the protocol and what we added, really to that was to go after
the primary end point data as well, and we totally agree that the mortality
date is undoubtedly more reliable in the sense of getting the data out on a
withdrawn basis.
DR.
MAISEL: One of the questions that we've
been asked to consider is whether we can consider the mortality data in
isolation or whether it should be part of a further analysis and I agree with
your comments that the sub-study certainly suggests that the New York Heart
Association class improves, 6-Minute Walk improves, Minnesota Living with Heart
Failure, Quality of Life improves. I
think there is evidence that the device is improving heart failure
symptoms. I'm just not convinced about
the hospitalization piece.
Finally,
I'd just like to touch on safety and I'll stop in a couple of minutes. I do not agree with what was listed as the
primary safety outcome, which is complication in patients that were
successfully implanted. I think for
obvious reasons, this leaves out attempted device implants which have relevance
to device safety. If we consider an
extreme example. If 90 percent of patients
die getting a device implant and the 10 percent who got it had not
complications, your report would list 100 percent, you know, safety and zero
complications. So do we have data on
the patients in whom events were -- devices were attempted but not implanted
regarding their complications, and perhaps data on that quote "Primary
safety outcome" but for complications in patients who had an attempted --
DR.
SAXON: Right, so you're right, the
systems safety definition is -- it's an FDA convention established in 2000 is
the narrowest definition because it only includes complications and serious
things in patients that were actually implanted. The system safety shown on the right here is the issue that
you're interested in. This is more
encompassing. This is all randomized
patients including unsuccessful attempts.
This not only counts those more serious complications, but also includes
any observation. So I believe that's
the answer to your question.
DR.
MAISEL: So if I read that correctly,
there was a very small number -- the rate was essentially the same in the -- of
the complications of the attempted patients.
DR.
SAXON: Correct.
DR.
MAISEL: Okay. And then finally in the tables that are presented both in the
labeling and in our submission, there are times when the numbers don't add up
such as there might be a certain number of complications, a certain number of
observations and then the total number is not the same. I can give you an example, the phrenic
nerve/diaphragmatic stimulation, there were eight listed complications and 52
observations but it says the total is 58 and those sorts of discrepancies appear
in multiple places. Can you explain why
that is?
DR.
SAXON: Right, so some of the things
that you think of as being consistently related to the LV lead actually aren't. Some of them are related to the RV lead for
instance, so that would lead to a miscount.
Some can be counted in both bins because you can have phrenic nerve
stimulation that can either to away or need or not need a programming change or
an intervention to correct. Or you can
have new phrenic nerve stimulation that wasn't initially counted.
DR.
MAISEL: So there can be the same event
in multiple patients, I understand.
Well, why don't I stop there.
I'll let some of my colleagues fill in some of the blanks?
DR.
BOEHMER: Could I possibly interject
something about hospitalizations? Your
concern was the total hospital burden to the patient, not necessarily being
represented by "all-cause" hospitalization.
DR.
MAISEL: I would say that is a --
stepping back from the trial, that is a clinical -- a question I have as a
clinician analyzing the data or looking at the data.
DR.
BOEHMER: All right, well, as a
clinician that takes care of a great number of heart failure patients -- by the
way John Boehmer, Penn State College of Medicine. My conflicts are as a consultant for Guidant Corporation and
investigator and some reimbursement for travel here.
This
is hospitalization rate by months. Now,
when I talk to a patient about getting a device, they understand that they're
going to get a device. And I will need
to explain to them that they're going to get the device in a hospital, but what
happens -- but if I'm going to tell them that it's going to decrease their risk
of hospitalization, they're not going to be confused about the fact that
they're going to go in the hospital and get a device. What they want to know is, "What happens after I get the
device", and this is all hospitalizations. This is nothing held back and the skill doesn't help it a great
deal because they have to show the initial hospitalization for all the patients
randomized to CRT-D but immediately thereafter there's a drop in the rate of
hospitalization. That's maintained
until you get laid out in the trial when you start getting into issues of who's
left in the trial because there is a survival differential.
And
I think just the quality of these data are reassuring to me when I would be
talking to a patient. I would never
suggest to them that they're going to magically get this device without going
in the hospital. That would be
unreasonable. Additionally, as things
evolve, maybe they won't have to go in the hospital as much. Maybe the techniques will get better, maybe
the care of them will get better. In
fact, this is already a moving target.
So I think this way of looking at the data and the way we actually did
it in the trial to give us a pass on the initial hospitalization which was in
the protocol, I think this is the way a patient can understand it. Thank you.
ACTING
CHAIR LASKEY: Now that you've put up
that confusing graph to me, there were twice as many patients in the CRT-D as
in the OPT so could you go over the Y axis on this, please?
DR.
BOEHMER: I'd be happy to. Those are rates of hospitalizations;
hospitalization rates, number of hospitalizations over number of patients at
risk in any given time point. So the
denominator levels it out.
ACTING
CHAIR LASKEY: So it is divided by two.
DR.
BOEHMER: Uh-huh, it's divided by the
number of patients at risk at any given time.
ACTING
CHAIR LASKEY: Thank you. Okay, let's attempt to confine our comments
to 15 minutes each, if possible, and we'll start with Dr. Kato, comments or
questions.
DR.
KATO: Well, a question for the sponsor;
you mentioned that a number of patients had in the CRT-D cohort, dysetinaria
(phonetic)sepsis. I guess there were 10
deaths there and five in the CRT-P cohort.
Can you explain a little bit
more about the sepsis? Was this related
to the device?
DR.
SAXON: You're correct, there were a
number of septic deaths and I can just -- there are enough that I can go
through them with you. They're not clearly
related to the device implant either temporally or looking at the clinical
history. For instance, there's a leg
cellulitis that was thought to have a history pre-operatively. There was an acute appendicitis, a PIC line
dialysis issue, septic shock in a dialysis patient, not an uncommon event,
cellulitis proceeding to an osteomyelitis, substance and setting of renal
failure.
One
issue that may have temporally been related to the device, although there was
proceeding phlebitis or potential prostatitis, colitis. So the vast majority of these events were
not clearly related to the implant and could be attributed to another morbid
event.
DR.
KATO: Thank you. One other question is, you know, in the
final assessment looking at a CRT-D versus CRT-P, do you -- you know, what do
you actually think is the final reason, if you can summarize in a couple
sentences why the CRT-D does better. I
mean, is it just that they are being paced and then they're defibrillated or
whenever they go into that rhythm and that's their final safety net or do you
have some other hypothesis or actual data behind that?
DR.
BRISTOW: I think what we can stand
behind is there is a reduction in sudden death in the CRT-D group compared to
OPT. There's not in the CRT-P group and
that might be expected, obviously, from the ICD component. So the ICD component is adding a reduction
of sudden death. Both devices are
reducing pump failure deaths and then additional reduction in mortality by sudden deaths. So if you look at mortality or a composite,
including mortality, although it's washed out by hospitalizations for the
primary end point, the CRT-D is obviously doing better for mortality.
DR.
KATO: Is there any data that you could
obtain from the interrogation of these devices after the patient dies or
certainly in the CRT-D group, is there any interrogation data?
DR.
BRISTOW: We have no interrogation data
to share with you today. We're in the
process of rounding that up but we don't have any. We do have appropriate device firing data which Dr. Saxon could
review with you, if you'd like which is consistent with this device in other
settings, other trials, and so forth.
DR.
KATO: Well, then in the CRT-D group, I
mean, how often did the device fire?
DR.
BRISTOW: I think it was 11 percent of
patients at one year and 19 or 20 at two.
We can give you the exact data.
DR.
SAXON: Now, while we don't have the
deaths, we have the interrogations that we think are relatively reliable from
the centers for appropriate chalks and
that certainly looks like 11 percent a year and around 20 months at 19 percent
for VT or VF therapy.
ACTING
CHAIR LASKEY: One question, I hate to
keep bringing up this hospitalization issue but I guess one of my question is,
if you couldn't identify the time of
the admission and discharge and you have to resort to the change in calendar
date, which is actually a typical method for hospitals, even hospitals to
determine whether somebody is hospitalized or not, how could you determine
whether the patient was on intravenous pressor support for four hours?
DR.
BRISTOW: I'll actually ask Dr. Carson
who reviewed these data as the adjudicated.
There obviously, was a special form that was filled out, the IV infusion
form. He'll give more color on that.
DR.
CARSON: Yeah, I think that's correct,
there was a separate form that we tried -- it was a follow-up case report
form. This was what I showed on the --
on my formal remarks, presentation this morning. It was that form that was filled out by a site that would give
the exact times of intravenous infusion of an inotrope or vasoactive
agents. As I said, the sites were not
asked to provide the information on discharge times or admission times. We could find admission times pretty clearly
in charts, but we could not really find discharge times in most patients and I
think the discharge time, as you know, is subject to some variability relating
to social issues as well as medical issues.
DR.
KATO: Right, but I mean, so that when
you're doing an infusion time, there's no -- you didn't record the start and
stop time. You just said the --
DR.
CARSON: We asked the sites to provide
that information on this form. We did
ask them to do that.
DR.
KATO: And so they could do that but
they couldn't do the other --
DR.
CARSON: Well, they were not asked to
provide that data.
DR.
KATO: Okay. Thank you.
ACTING
CHAIR LASKEY: Dr. Yancy.
DR.
YANCY: Thank you, Warren. One question briefly and then a few
comments. And it pertains to one
particular graphic shown in the FDA analysis and it's specifically the FDA
analysis when we tally the secondary
end point and it shows sudden cardiac death event rate per 100 patient years
and numerically, at least the CRT-P group has a higher sudden cardiac death
rate. The question is, is that a
statistical blip or do we think that that's an issue that needs further
thought?
DR.
BRISTOW: Is that addressed to FDA?
DR.
YANCY: Whoever can answer that, if it's
FDA or if the sponsor can --
DR.
BRISTOW: Well, since you're referring
to the FDA analysis, why don't we allow them to comment, then we'll respond?
DR.
PROESTEL: Well, it was a concern that
had been brought up actually to us through public presentation. So we were curious to know in the CRT group
what was going on with sudden cardiac death.
I think for the purposes of the CRT-D device, the FDA can say that we
were reassured that in fact, pump failure death overwhelmed that increase in
sudden cardiac death. I mean, there's a
number of reasons why we should be skeptical about that sudden cardiac death
blip. It's obviously, a sub-group
analysis. It was not
pre-specified. There is the issue of
competing risk. You know, so what I
would say is that for the purposes of the CRT-D device, we were reassured that
in fact, "all-cause" cardiac death as well as "all-cause"
mortality was improved in the CRT arm.
And you know, it was -- as far as statistical significance, I wouldn't
calculate P values for those.
DR.
YANCY: Well, that's my reason for
bringing it up because I think that right now the record from this morning's
discussion states it was increased and I don't know that we can say that
comfortably and I would not want that to stand as a matter of fact.
DR.
PROESTEL: That's correct. These were really point estimates.
DR.
BRISTOW: We agree with that and, in
fact, if we can just show the Kaplan-Meier curves and so this is sudden death
Kaplan-Meier curves and basically there's no statistically significant
difference between A and B, which is CRT-P and OPT, the P value of .495.
DR.
YANCY: Thank you. Warren, my comments are more along the line
of my perspective as a clinician who does this kind of activity on a day to day
basis. And I don't know if this is
where you want me to speak to that or not but I think it's germane to the
discussion we've been having. And the
first thing I would say is with regard to the implication of hospitalization,
not all hospitalizations carry the same weight and in the context of a heart
failure patient, a heart failure hospitalization carries with it an
extraordinarily high incidence of rehospitalization and a 12 months very high
rate of mortality and so I think that if there is even a signal that the
hospitalization is impacted as a practitioner who takes care of desperately ill
patients with this condition, I think that signal needs to be respected.
But
I think even beyond that, as someone who actually helps participate in the
writing of guidelines that govern how heart failure medicine is practiced
across the country, there is pressing need to have clarity on where this
technology resides and I think for whatever worts we may have uncovered, this
is the best data base we have right now for patients with advanced disease who
are at very high risk for serious events hospitalization and death and so in my
judgment, I would want to go on record publicly for commending the
investigators for working with a difficult patient population and bringing
together important data and I think that even though we may quibble with some
of the definitions, and may have to wrestle with how this was dealt with
statistically, I honestly believe what I've heard so far is gymnastics and not
substantive and I would rather accept the implications as they are. So I have no further questions.
ACTING
CHAIR LASKEY: Dr. Brinker?
DR.
CARSON: Pardon me for a moment. Dr. Laskey, could I just make one
clarification on the response to Dr. Kato?
I just didn't want to confuse the issue of what you were asking because
I think there was some confusion in the morning between the four-hour inotrope
infusion and the hospitalization criteria.
In terms of events that were in the primary end point, hospitalizations
were "all-cause" with a duration criteria. They did not require four-hour inotropic use of anything. That was an outpatient end point to be
considered part of the primary end point.
And
in the response I gave to you earlier, we actually did not attempt to
necessarily capture whether an infusion was four hours or later during the
hospitalization except as part of the morbid end point but it was -- except to
count as one of the morbidity criteria.
The form that we used particularly was for the intravenous therapy as
part of the CRF for the morbid end point but it was the outpatient end point
that was particularly at issue.
ACTING
CHAIR LASKEY: Jeff?
DR.
BRINKER: I just have a few
questions. Have you tracked changes in
medications level between the two groups and in fact, whether --
DR.
BRISTOW: Yeah, we have and we'll show
you some data there.
DR.
BRINKER: While you're getting that up,
one of the concerns I have is that there's an implication in somebody's
reviewed this packet, I don't know who I can attribute it to, that the device
group had a higher incidence of hypotension dehydration thought to be due to
the maintenance of a medical therapy coupled with the beneficial effects of the
device resulting in an over-medication state, if you will.
And
I'm not going to argue that point at all because that would be a good end point
if such occurred, but what I really want to make sure is that one group or the
other perhaps had a decreased hospitalization rate because of medication
change.
DR.
SAXON: So patients did have an
outpatient follow-up, but it is true that in some patients who have this
well-described dramatic dieresis improvement in blood pressure with the onset
of resynchronization therapy need to be followed particularly if their
medication is not adjusted and, you know, it's very difficult to typically
adjust it or know how to adjust it. So
I would state that, yes, it is a possibility that a dramatic improvement in the
systolic response would cause a marked dieresis that could potentially in some
patients lead to an event like that, but I would suggest that the patients were
tracked in such a way that that was probably a very rare occurrence.
DR.
BRINKER: Just out of curiosity, are you
suggesting there should be a caution in the labeling? Are you suggesting that --
DR.
SAXON: No, I guess I'm responding to
your question, could you theoretically develop and I would say, yes, you
could. You could -- if you were, for
instance, requiring more diuretic dosage, you had an improvement in your
clinical condition --
DR.
BRINKER: We don't have any evidence of
that.
DR.
SAXON: -- there's no data that
indicates that that --
DR.
BOEHMER: Just one piece of data, one
piece of data that we do have, we do have ACE inhibitor and Beta Blocker doses
over time. The ACE inhibitor doses are
in an Alaprol (phonetic) equivalence.
If you saw a substantial number of patients with significant volume
depletion you would expect two things to occur to them. One is that they would become hypotensive. The second is that they would become
asotemic, both reasons that clinicians will obviously respond by reduction in
doses of ACE inhibitors and this is over the 12 months of the trial with every
time point, including the one week and one month time point and there's not
even a blip.
DR.
BRISTOW: And so with regard to the Beta
Blocker data, the majority of patients were on Carvedilol. It's a lower set of curves. OPT actually has a slightly higher average,
daily Carvedilol does throughout the trial.
I don't know if that's statistically significant. You can see the absolute difference. And then a minority of patients are on
Metroprolol and these are very small numbers as you get out there with OPT in
particular, 17 at the end, so there's no consistent change in Beta Blocker dose
and baseline Beta Blockers are exactly the same.
DR.
BRINKER: So what I might have expected
is a change if not a decrease in medical therapy in the device group and
increase in the drug treatment group and maybe we're missing diuretic therapy.
DR.
BRISTOW: Well, the idea is there
patients were maximally treated when they were enrolled, background medical
therapy. There was nothing else for
them to go on that had any proven benefit in heart failure and they were on
everything at supposedly the target doses that they should be on and so one
answer is, there was no room to maneuver it in an upward direction at
least.
DR.
BRINKER: My experience is there's
always room for Jell-O. There's almost
always some manipulation that can go on.
Maybe that did go on in terms of some diuretic or maybe even in the
other group in intravenous therapy.
DR.
BRISTOW: Perhaps, but, you know, these
are chronic heart failure patients taken care of by heart failure physicians,
physicians with at least an interest in heart failure and they were well
treated coming in and they were well treated throughout the trial.
DR.
BRINKER: This next question I have is a
little bit of a variation of the one I asked you before. And after thinking about it, I might not
have asked you the complete question.
That is, do you have difference in hospital burden maybe best described
in total days in the hospital in the two different groups rather than
admissions and durations averaging?
DR.
BRISTOW: Total days. Somebody grab that data. I don't think we have it on backup but we do
have a text of it. I can tell you the
hospital duration of the two groups because I gave it to Dr. Somberg
earlier. So the average days in the
hospital which is what I gave him, 8.6 days on CRT-D and 10.9 on OPT, this is
of the hospitalizations, the average days in the hospital. Total number of days -- is that normalized
to size of the cohort? Well, that's
double so that doesn't mean anything.
We don't have the data normalized to the size of the cohort for total
number of days.
So
the best thing I can give you is what I just gave you, the duration of the
hospital --
DR.
BRINKER: Would you agree, however, that
a better indication hospitalization burden is the total number of days rather
than -- assuming there's a meeting rather than --
DR.
BRISTOW: Yeah, I would agree with that
within the hospitalization measurement or the hospitalization event by itself,
the most sensitive measure is probably the total number of days. One could argue, it should be the total
number of days per patient, obviously which we just gave you. On the other hand, remember you've always --
in a trial like this where mortality is being effected by one -- by the
treatment, you have the issue of competing risk and so if you're an OPT patient
and you're dying with a higher incidence, you can't be hospitalized. So that's always an issue in these
hospitalization data which in and of themselves or by themselves, I think need
to be taken with some caution.
DR.
BRINKER: My final question is, how many
patients left the pharmacologic arm because they developed criteria for a
defibrillator. In other words, how many
people got a defibrillator alone?
DR.
BRISTOW: Okay, not many but we'll give
you the real number.
DR.
BRINKER: Two.
DR.
BRISTOW: Something like that. Two, okay, yes. That's it.
DR.
BRINKER: So interestingly, all the
other people left for presumably CRT-D.
DR.
BRISTOW: Uh-huh, right.
DR.
BRINKER: Okay, thank you.
DR.
BRISTOW: There were CRTs as well. We'll give you the actual number.
DR.
BRINKER: That's close enough. I don't want to burden you.
DR.
BOEHMER: Well, interestingly, there
were a substantial number of patients in the OPT group that were withdrawn and
not implanted with anything. As you can
see here, the total number withdrawn were 80.
Thirty-one received CRT-P which was the first device approved in the
course of the trial. Eleven received
CRT-D and two received an ICD, giving you a total of 44. About half the patients withdrawn did not
receive anything.
ACTING
CHAIR LASKEY: Well, then where did they
go? Did they just die?
DR.
BOEHMER: It's, I suppose, a common
circumstance in a clinical trial that the group not doing quite as well ends up
either withdrawing or stopping therapy at a higher rate, so those might be
explained in that regard. Not everyone
was withdrawn to receive the device.
That's the important part. It
might be -- you know, in centers such as mine, people travel a long distance to
come see me and if they ended up in a control group and the ride kept getting
longer and longer and the winters kept getting smellier, they may not come the
next time and withdraw consent.
DR.
BRISTOW: But to answer your question,
some were end pointed. We showed some
data about the number of end points we got out of the withdrawn patients. Some were not end pointed and we were able
to follow them till December 1, 2002 and others we could not ascertain, so it
was sort of a mixed bag in terms of what happened to them.
ACTING
CHAIR LASKEY: Good. Thank you.
Dr. Normand.
DR. NORMAND: Okay, I have a few detail-oriented questions and then some
general questions. And so the first
question I have has got to do with -- and I know I'm going back to the
beginning but inclusion and exclusion criteria and I just am not understanding
something and it's probably pretty obvious and that is I think people had to be
hospitalized for heart failure within the previous 12 months was an inclusion
criteria.
DR.
BRISTOW: Right.
DR.
NORMAND: But then the exclusion
criteria said you couldn't be hospitalized in 30 days prior to enrollment.
DR.
BRISTOW: Right.
DR.
NORMAND: So it's really within 11
months.
DR.
BRISTOW: So the concept here is we want
the previous heart failure hospitalization because that -- we know that that's
associated with a higher event rate mortality and subsequent heart failure
hospitalization, so that's the reason for that. But we didn't want unstable patients. We thought that would be a risk for device implantation.
DR.
NORMAND: Okay. Now, I have a question about the
randomization by center. At one point
there's a number of 128 centers and then it goes down to 116 centers. The difference are centers that never
recruited anybody?
DR.
BRISTOW: Yes, let me get some help with
that from someone, Dave or Fred or somebody, the 12 differential here. These are centers, I think, that did not
finish in -- as active centers, but let me get confirmation of that. Sorry, with the slow kinetics here. This is a question we had not anticipated,
as you can see.
DR.
NORMAND: I might have a few more about
the centers, so keep the binder open.
DR.
BRISTOW: We'll keep working on
that. Why don't we ask another
question?
DR.
NORMAND: Okay, the second question,
unfortunately is related to the centers and that is, I believe in the FDA --
maybe the FDA can answer this one, though.
The FDA indicated that several of the centers only randomized to one arm
-- one of the treatment, either just pharmacy or medical therapy or not. I just want to understand why was that the
case. Is it the case that the centers only had a accrued one person?
DR.
BRISTOW: Yeah. Yes, in some -- yeah, I think generally very
small numbers of patients and so the blocks that they had didn't allow
enrollment in the two groups. They
didn't get to those assignments.
DR.
NORMAND: So it's 12 centers and four
centers, 16 centers in total. I just
want to make sure that indeed that's the reason. The numbers were so small and hence, they couldn't be randomized.
DR.
BRISTOW: Right.
DR.
NORMAND: They were stuck in one group.
DR.
BRISTOW: Right.
DR.
NORMAND: Okay, I didn't see any of this
data so --
DR.
BRISTOW: Which is common -- which is
common in clinical trials to have these low enrollment centers and that's what
happens.
DR.
NORMAND: Okay. I just wanted to go a little bit over the
blinding and the collecting -- do you have an answer?
DR.
FELDMAN: Yeah, 116 centers had an OPT
patient and so the others had a non-OPT patient, either a CRT-D or a CRT-P.
DR.
KRASNICKA: OPT plus CRT-D, 116
patients.
DR.
NORMAND: Okay, and so the remainder
were on the other --
DR.
FELDMAN: Were on the CFT-P, that's what
that is, okay.
DR.
NORMAND: Okay. It's just nice to know. I didn't know what happened with the data,
that's all. I have a question about
blinding. This relates to collecting
data after the patients withdrew from the study and I do want to echo the
comment that I think this is an extraordinarily good thing that was done on
behalf of the sponsor and that is to collect data from patients that
withdraw. The intention to analysis is
only unbiased under certain conditions and when you have missing data, it's
biased. So I'm pleased that that was
done.
However,
I do have some questions regarding how the data were collected given that there
was no blinding, I think of certainly the deficient participants and the --
DR.
BRISTOW: Investigators and study
coordinators were unblinded. This is an
unblinded trial and that's one of the big factors, obviously, creating this
differential withdrawal.
DR.
NORMAND: So, again, how were the -- so
in terms of the CRF form, for example, when you're going back to the patients
that withdraw from the study, obviously they knew which ones were in which arm,
and so I had heard a discussion a little bit earlier, I don't remember who
asked the question, but it had to do with some hospitalizations and things such
as that. So that was the information
that somebody went into the medical record, collected that information that was
verified to say, indeed, they didn't have a hospitalization.
DR.
BRISTOW: Right, so again, the same
policies were followed. The patients
that were withdrawn and then data harvesting was accomplished, there had to be
source documentation. Every attempt was
made to get at the source of -- the verifiable source. All the data were assembled in a dossier for
each patient, reviewed by that adjudication committee. The adjudication committee had sort of
pseudo-blinding as Dr. Carson talked about.
Of course, the coordinators and investigators were unblinded but they
had equipoise from the standpoint of the trial presumably.
We
had no idea which -- what was going to happen in this trial and the idea was to
go get all the data in a very even-handed way.
DR.
NORMAND: And I'm a little bit surprised
in the descriptive statistics, the base link characteristics that there were no
missing data. It's -- I'm happy for
you. I just wanted to make sure that,
indeed, was the case, that there were no -- it was fully collected, that there
wasn't a default to note or anything, that that was --
DR.
BRISTOW: Dr. DeMets, do you want to
comment on this or anyone? I guess we
can apologize for having too complete a data set, perhaps. I don't know what to say about that.
DR.
DeMETS: I don't have the data in front
of me, but clearly -- I mean I wouldn't say that every variable of a cast of
thousands that were collected, that they're all filled out completely but for
the key end points, key as in baseline variables, I think that's correct. We had it all. So the information in the baseline case report forms, we got 100
percent of them.
DR.
NORMAND: It's all right. There's no need to apologize. I was just trying to figure out if that was
--
DR.
DeMETS: I understand. I mean, a variable may not be, but the forms
are there.
DR.
NORMAND: I know. I'm going to start with more questions
regarding the hospitalization again and the mortality analysis. And I think I'd like to characterize my
understanding of the FDA's analysis and if I could, I'm going to give my
interpretation to the panel and I want the FDA to correct me or say that's not
really what you're saying or that's what you're saying. So my understanding is the following. That in terms of the primary end point there
is a concern that the assumptions for the Cox model are not met and what that
would imply seems to me would be that there was a crossing of the curves and so
that if you declared that one therapy was better than another. That wouldn't be
true. It would be true on average but
it wouldn't be true at all points in time.
Is that the FDA's position?
Yes.
Now,
I realize you're -- you know, with the data set it's very difficult to say it's
clearly violated or not clearly violated.
I'm at the point where I'm confused now because if it is violated, then
I don't believe the analysis at the end of the day. I believe the average -- on average, it may have been beneficial
but -- so the question is really for the FDA right now. In terms of if we agree that the hazards do
cross, then it's not proportional, then I'm not sure what to conclude at the
end of the day. So somehow I feel it's
really important to know whether or not the assumptions were violated.
In
your notes you're saying it may be violated.
Do you have any more information on that?
DR.
KRASNICKA: Based on the hazard
functions I think the hazard -- the proportional assumption is not true. And when I look at -- I tried to analyze
this data from a different point of view and I notice that this data has a lot
of noise, so it's difficult to analyze during a very short time.
DR.
NORMAND: I didn't hear the last
word. A lot of knots it sounded like.
DR.
KRASNICKA: Noise.
DR.
NORMAND: Noise, I thought --
DR.
KRASNICKA: Noise.
DR.
SOMBERG: What noise can there be? They're deaths or they're not deaths? Are you saying that they were reported one
says death and one says not a death?
DR.
KRASNICKA: No. From -- when I adjust for the baseline and I
look what is going on with treatment, with treatment estimation, coefficients,
I notice that it's changing sign from minus to plus, so I don't believe that
the proportionality hazard assumption is true.
DR.
NORMAND: So how do you feel about the
Kaplan-Meier analysis then?
DR.
KRASNICKA: Because of the important
assumption not for censoring, I have problem with Kaplan-Meier.
DR.
NORMAND: I'm wondering if perhaps,
Professor DeMets could say a few words about this as well. Again, the reason why I'm struggling a
little bit about it is that for something where, you know, the Log ranks an
average and on average I'd like to know sort of at what time -- over what time
frame is there a benefit if, indeed, there's a question about things changing.
DR.
DeMETS: Thank you. Well, let me try to summarize some of these
issues. As I tried to point out this
morning, let's examine the four -- three or four analyses. First of all, the Kaplan-Meier makes no
assumptions about proportionality. It's
totally parametric/non-parametric. It
makes no assumption about non-informative censoring. But the way you address that and the only way I know to address
that is to get all the data and we tried very hard to do that and I think came
very close.
So
the Kaplan-Meier analysis is not in question at all. Two, the log rank test which is used to compare those two
Kaplan-Meier curves also makes no assumption about proportionality appendix. Not from the very beginning did Mantel and
Haenzel develop that test. And again,
it's documented in here. So it's not a
requirement. Yes, there's some
optimality principles if you have proportional hazards.
As
a footnote, I would say that the Wilcoxin and the log rank test are members of
the same log rank family, just that the
weight is different, so whatever assumptions are true for one are true for the
other in terms of those kind of assumptions.
But at any rate, so as far as I'm concerned, the log rank test is not in
question, again, with the issue of -- from the censoring which we've addressed
by getting all the data. Those two
statements are not my opinion, those are mathematical facts.
Where
we have some judgment here as to whether or not the methods that purport from
hazard Cox model fits and if you want to bring up backup slide 71, say, which
was shown with the shown failure residuals.
Now this is a complicated technical matter, I recognize, for
non-statistical colleagues, but what's plotted there, the residuals, and their
confidence levels, you'll notice the dotted lines of the confidence levels,
that they, in fact, include the linear straight line. So you cannot reject the hypothesis that these fit. As a matter of fact, that's what Dr.
Lawrence did.
If
you correlate the residuals with time, you get, you know, P values that are not
significant, right? So it would be a
tough argument to say -- to reject that.
You can say, well, of course, it's not a perfectly straight line. But more important than all of that is the
reason you keep seeing the Cox model used over and over again for the past 30
years, it's a very robust method of analysis.
You can violate assumptions dramatically and it's still a pretty trusted
tool. That's why we keep using it in
trial and trial. But I would say that
from my opinion and from my colleagues at Wisconsin and Dr. Lawrence, is that
these assumptions are not violated.
So
the first analyses there's no question.
The third one, we could discuss that but I don't, from my perspective and experience and my
colleagues, it's just not a statistical issue.
Now, the withdrawal issue is common to all of these methods if you
assume non-informing censoring. And I
was not happy when we got to the point of November of 2002 that we had this
many withdrawals because you know, it's hard to argue definitively when you
have that many.
So
we went and tried to minimize that and you've acknowledged that. So that's the solution for that but that's
common to all the issues. And you try,
very hard, of course, to get every observation. We didn't quite make that but I think the important part for me,
to my satisfaction was on the CRT-D arm and we wound up with four missing on
the primary end point and six, I think on the morality.
As
a comment I would say, you know, when we stopped the trial when it came to its
termination point, at that point in time and with the updated data, if you
analyze the data censoring anybody at withdrawal because you don't take into
account any of the withdrawal data, you still have a significant result. Now, I don't like that analysis because I
argue that it doesn't take into account the informative censoring, but if you
looked at that, you still have significance.
And then one final point is that if you look at the core rates that have
been listed, no, there's nothing significant but you could say, well, maybe
it's loaded somehow in one sense or the other.
So we typically do multi-variable analysis and so in this case. The two risk factors that stick with you in
such analysis are New York Allergy and the New York Heart Class.
In
the presence of those and in the presence of all the other cohorts, the
treatment effect is still significant and that's in your packet. It would take me awhile to tell you exactly
which page but it's in there.
DR.
NORMAND: No, I --
DR.
DeMETS: So we've done, we think our
standard conventional due diligence analysis to address the issues that have
been discussed throughout the morning. Thank you.
DR.
NORMAND: Thank you. I was wondering if
the sponsor could tell me what percent of hospitalizations occur on the same
calendar day or at least CHF admissions, I mean admissions and discharges, like
a one-day hospitalization.
DR.
CARSON: Yeah, you're talking about a
single calendar day change.
DR.
NORMAND: No, I'm asking how many --
what -- does anybody know -- you could do all hospitalizations or maybe you
just want to do -- so all hospitalizations for adults that a patient is
admitted and discharged on the same date, does anybody know that number? You don't know it, because you could find
that number.
DR.
BRISTOW: We did not track that
number. You had to have a calendar date
change to get a case report form to get adjudicated.
DR.
NORMAND: I realize in your trial but
did you look anywhere else for that so we could ballpark sort of how many --
you don't have that --
DR.
BRISTOW: I don't think we have any
information on that. Our personal
experience, John may want to weigh in, you know, it's not a very large number,
probably less than 10 percent but John you might comment on that.
DR.
BOEHMER: Yeah, as previously mentioned,
a hospital admission, at least just about any payor is a hospital of at least
23 hours duration and you can write admission orders. What you're doing is observing a patient and historically, what
we try to do in clinical trials is distinguish ER visits from hospitalizations
from unanticipated doctors' visits and that's where this evolution of the
24-hour or greater than 23-hour definition came from.
Less
than 23 hours is, indeed, not a hospitalization. You can write admission orders and you get paid for an
observation eventually, and it's very confusing to then distinguish, well, was
he really admitted or was he just in the ER?
Did he get to a hospital bed or was he discharged before he was
admitted? This was an observation, this
was -- when you're in the hospital for a full day, you were admitted to the
hospital and we took things that the center said was an admission, everyone at
the center said was an admission and lasted over a calendar day, which just
about any payor, I believe, to pay for an admission and I'm sure Medicare would
say that that's a hospitalization. So
that was the evolution of it and from a practical sense, you know, you could
write admit and discharge in the morning or in the afternoon. You don't get paid for a hospitalization and
it's not the same thing. It's the same
as an ER visit and it becomes very confusing in a clinical trial to distinguish
those two.
We
got everything that was a hospitalization admission, a hospitalization of any
sort that lasted over a calendar day change.
DR.
STEINBERG: If I may just add one
thing. We may have one piece of
information that addresses your question.
I'm Jonathan Steinberg. I'm one
of the M & M committee members and am a consultant for Guidant. The IV inotrope more than four hours was an
end point that was often met in the emergency room. Patients might come in and then go home the same day. And so we did track that specific end point
in the trial and that was actually a very small number of end points, in
particular, a very tiny fraction of the total hospitalization numbers.
DR.
CARSON: If I can just make one more
comment to make you sorry you asked, but the --
DR.
NORMAND: I am sorry I asked.
DR.
CARSON: You're right. The only trial that has ever had at least a
statistic that I could find out on this was the Overture trial. The people running the Overture trial became
concerned because this issue arose during the hearing with the Cardiorenal
panel in 2001 on VALHeft. They looked
at all the data they collected that was one hospital day or less and they found
out for heart failure hospitalizations at least, that was seven percent of the
total heart failure hospitalizations.
But that is one day or less. So
therefore, whatever number we're talking about I would think would have to be
considerably less than that.
DR.
NORMAND: And I guess I just wanted to
understand when the case report forms were developed, the reason why I ask
this, it's got to do with the fact that you indicated that greater than four
hours was -- you know, there's a separate form on the body of questions on the
form for that, yet, for defining a hospitalization, there was just a date. It's the last question for me about this --
but when was that developed. Why wasn't
a sort of admit time and discharge -- because we do this all the time in terms
of -- so when was the case report form, was that made in the absence of
coordination with --
DR.
BRISTOW: Well, the case report form,
the C2R need to weigh in potentially on this but so CRO, develop the case
report forms, they were looked at by everybody. I think this probably is something that slipped through the
cracks. Realizing though, that even if
you had it on there, you're not going to get that filled in necessarily --
you're not going to get it filled in until you do a lot of digging. The coordinator -- this is not information
that's readily available to the coordinator.
DR.
NORMAND: I understand. So what doesn't get filled in? I just didn't hear you.
DR.
BRISTOW: The dates. The date of admission might be but, you
know, precise time of discharge with an issue is 26 versus 23 hours and so
forth. I mean, that's going to be --
we're going to have to go digging for that.
It was not on the original form.
That's the issue. Somebody could
provide a little more color on that from the group.
DR.
BOEHMER: This had to be filled out
under two circumstances. One is when
the research staff became aware that such an event did occur but if the patient
came in for the routine follow-up visit every three months, they were asked if
they received intravenous medicines in the hospital over a four hour
period. It's a follow-up form, a
regular follow-up form, so along with, "Were you in the hospital, did
anything else bad happen to you", et cetera, et cetera, et cetera, this
was tracked.
DR.
BRISTOW: So the real answer is that the
original case report forms had the dates, did not have the time.
DR.
NORMAND: So it never had the times.
DR.
BRISTOW: It never had the time and that
just -- and so, you know, that wouldn't be an issue unless it's a matter of 23
versus 26 or whatever and that just wasn't on there. And so they couldn't -- basically, the adjudication committee
could not deal with this.
DR.
NORMAND: If it's not there, you can't
make it up. Okay, thank you.
ACTING
CHAIR LASKEY: Which is amazing, because
if we don't date and time our notes and orders now, we go to prison. So I just find that kind of ironic. I just had one question/way of departing
from this statistical discussion and moving it more towards the clinical
realm. While we understand or we hope
we understand that the log rank analysis, Kaplan-Meier curves represents an
overall on average kind of measure of the difference of the area under the
curve, oncologists looked at this data in another way which is just the
difference in days to first event.
Can
you -- I'm finding it hard to just read the small print because the plots are
so small, but what is the median difference in days from first event to your
primary end point?
DR.
DeMETS: I don't know if we have a
backup slide for that but I calculated it and for the OPT arm it's 209 days and
for the CRT-D device it's 269 or 270 days, something like that, 209 versus 269
or 270. Now, for mortality, you can't
compute that statistic because --
ACTING
CHAIR LASKEY: No, right.
DR.
DeMETS: Right, the primary as we've
presented it.
ACTING
CHAIR LASKEY: Sixty day's difference.
DR.
DeMETS: Yes.
ACTING
CHAIR LASKEY: For the average patient.
DR.
DeMETS: Right.
ACTING
CHAIR LASKEY: Thank you. Dr. Krucoff?
DR.
KRUCOFF: I guess it's pretty clear that
what we're wrestling with here is an ambiguous data set from an experienced,
obviously dedicated group where it's raised a lot of concerns. And I guess I break this out into three
aspects of what about the ambiguities in the data really matter versus what
don't, and hopefully, that will move us a little bit toward a conclusion.
I
think one level is just whether the definition changes and the process changes
that occurred over the time line of this trial were driven by quality concerns,
which I think we've heard expressed from the sponsor group pretty clearly. If you find out, oops, we've got a case
report form that actually doesn't give us time of day and our primary end point
as defined by time of day, how can we get a higher quality definition of that
end point? We don't perceive it as
substantial. We think it could be more
active, more dependable. That, to me,
is sort of a steering process toward a higher quality intention.
But
the flip side of that is anywhere that that opens the door to bias or to a
shift or a change of definition of the primary end point along the way, that
makes the data actually less interpretable or how much bias gets involved in
the data less interpretable, that's where we're at least from my perspective,
getting ready to tear our hair out here because there really obviously is both.
So
let me ask. I asked the sponsor and Dr.
Proestel from FDA if I could ask you, I guess one of the things that I would
like you guys to comment on is are you all aware of any suggestion at any point
along the way that these definition changes were actually driven by awareness
of the data enrolled to the point prior to that change as opposed to changes in
the landscape as we've heard discussed.
Are you all at any level aware of any communication of actual data from
the trial that might have overtly influenced these definitions?
DR.
PROESTEL: No.
DR.
KRUCOFF: Okay, and I think we already
heard from the sponsor, the chain of communications to my question
earlier. I think the other two levels
then that I go to with ambiguous data is how much do the definition changes
erode just the certainty level as to how certain can we be the conclusions are
free of bias and likely to be reflective of practice after a device is out in the market versus how or
whether or when any of the changes of assumptions here actually change the
interpretation, change the conclusions?
So
for instance, we've talked a lot about the withdrawals. The one assumption that was interesting to
me because it appeared so frequently in the panel pack that the withdrawals
were because the OPT patients were getting sick and needed a device so they
pulled out of the trial so they could go get a device. The fascinating part to me is that actually
bias against the device. So let me come
and I have to thank Sharon-Lise for doing a lot of my work and it's going to
make my part much shorter, but let me ask whether the reverse may actually be
true or whether there is any sense that patients in the medical group who are
healthier might have been pulled out to go get a device.
So
I think we've got the FDA's comments, so I'm going to ask the investigators or
the sponsor team, do you all have an impression as to what drove the withdrawal
and whether it was relative in any way to the level of illness in the patient
population in the OPT group?
DR.
BRISTOW: Yeah, I think we all think it
was linked to patients worsening with heart failure and the investigator and
the patient because it's an unblinded trial lobbying for device
implantation. It certainly would not
track in our experience of doing well.
DR.
BOEHMER: And we did look at the
baseline characteristics of the patients who withdrew versus those who didn't
and they were identical in any way.
DR.
BRISTOW: But that's baseline. It doesn't speak to what's happening during
the trial.
DR.
KRUCOFF: Right, at the point they
withdrew -- we don't happen to have any data about the level of illness or
whether they had changed from their baseline interval to --
DR.
BRISTOW: No, we do not.
DR.
KRUCOFF: -- a three or a four or
anything like that at the time they actually withdrew.
DR.
BRISTOW: Not that I'm aware of.
DR.
BOEHMER: As Dr. Bristow pointed out
this morning, the data in the preliminary analysis before the patients who
withdrew were obtained, was qualitatively identical to the data set when it was
more complete.
DR.
KRUCOFF: Okay, so then as far as I can
tell, most of the other concerns about assumptions that might actually change
the conclusion from this set of data are work that hasn't been done, which, you
know, I can tell you from my perspective this is something I'm really sorry to
hear that from both sides, from -- you know, you've clearly got the fire power
on the sponsor's side as FDA to address some of these questions. If we have an enrollment profile that has a
higher instance of Class IV heart failure and ischemic heart disease in the OPT
patients, where is the analysis that corrects for that? Where is the analysis that we can look at
that? If you have it that would be
great.
DR.
BRISTOW: We did -- Dr. DeMets just
mentioned that analysis.
DR.
KRUCOFF: I mean, I've heard -- do you
actually have it here?
DR.
BRISTOW: Yeah.
DR.
KRUCOFF: Can we see it?
DR.
BRISTOW: Sure. Can we get it up? It's in the packet.
DR.
KRUCOFF: I will apologize, I missed
that.
DR.
BRISTOW: But the punch line is that,
Dave, you might want to give the real data, but --
DR.
KRUCOFF: Okay, is it --
DR.
BRISTOW: -- etiology and Class III and
IV made it through a unvaried analysis as did treatment effect, and treatment
effect survived the multi-varied analysis with those factors in.
DR.
KRUCOFF: For the primary end point or
for mortality?
DR.
BRISTOW: Okay, it's green Tab 5-3,
sub-tab E, let's open it up.
DR.
KRUCOFF: I'm sorry, one more time,
green --
DR.
BRISTOW: Sorry, that was a
misdirection, one second. All right, so
go ahead and say what it is.
MR.
ECKLAND: It would be on green tab 5,
subtab 4, section B, page 4.
DR.
KRUCOFF: Five, 4B?
DR.
BRISTOW: Now, is this memory end point
or is this -- so that's the survival analysis.
DR.
NORMAND: Table 6.
DR.
BRISTOW: Table 6 is the survival
analysis and it's just as I said.
DR.
KRUCOFF: I'm in 5.
DR.
BRISTOW: So on multi-varied analysis,
we've got New York Heart Class, ischemic, non-ischemic and treatment making it
through statistically significant.
DR.
KRUCOFF: Okay, that's primary end
point. Was this done for
mortality? Thank you. I just overlooked that. I mean, to me these are probably the most
important things to -- if we have possible ranges of assumptions, there's more
than enough statistical power to begin to look at.
DR.
BRISTOW: Yeah.
DR.
KRUCOFF: Do these assumptions actually
change the interpretation of an outcome and we have two ranges of outcome
here. There's mortality which I don't
think anybody here has any trouble with, and then there's the primary end point
which is trying to get the simple trial concept of "all-cause"
mortality and hospitalization and for whatever purposes, quality or other,
what's made it not so simple is that the definition evolved over time.
DR.
BRISTOW: Yeah, exactly.
DR.
KRUCOFF: And I think the key question
in my mind is, is that a fatal problem or is it just sort of an annoying
problem but there is, in fact, enough information to separate out those two.
Let
me shift, in fact, David, while you're there, one of the things that I was also
-- do you want to take your book back -- led to is the impact on the
Kaplan-Meier curves which again, from -- in the slides I have quickest
reference to from the FDA presentation but on mortality, where around the
300-day range there's sort of the best separation and then the curve sort of
tail together again, and in part, I think that's pretty clearly that there are
probably smaller numbers and where the slide that, in their presentation, is
eight pictures later or where the confidence intervals between the treatment
arms begin to overlap and actually sort of bump into each other a little
earlier, do you all have a sense of whether that's because of the lower numbers
of patients who are followed up to that level or because there's really a
difference in behavior and one of the behaviors, of course, physiologically, we
worry about with anything that stimulates the ventricle in heart failure is are
you stimulating it for the good or are you stimulating it as a setup to later
mortality. So can you --
DR.
DeMETS: Let me comment on those
two. First, I pointed to the
"all-cause" mortality figure.
You can tell by -- I mean, your eye always seems to drift to the right
but you can tell from those curves, that the side, the jumps, the steps, if you
will, on those Kaplan-Meier curves, what that tells me and if you look at the
tables which are behind those graphs, that the number of patients at risk that
file out is small, so a single event will make a major step. So you know, perhaps we should stop graphing
all of them but then that doesn't feel comfortable either.
So
we have to train ourselves to sort of, you know, look at the entirety and not
look at the right-hand side. The log
rank test, of course, and any -- we had ranked statistic, tries to encompass
the entire survival curve and the differences there and various tests, you
know, will weigh things differently.
The log rank is a standard that one would use almost always. The corollary to your question is that
because of the number of events and the number of patients at risk declining
with time as it must in any stated entry real life trial. The formula for the stated error of the
Kaplan-Meier curve guarantees that levels are going to get bigger with time
because there's less information. So
that's kind of intuitive.
You
know, the reason -- I mean, the Kaplan-Meier paper was published in 1958 as the
way to analyze time to event but it was not satisfactory because we were left
with this point by point comparison. So
it's Y. Mantel in 1966 with Haenzel proposed the log rank test and, you know,
weeks, later literally again proposed the Wilcoxin test is because nobody was
happy with this point by point comparison.
Since
then, we have advanced a field a lot in terms of mathematics but not really
much in concept. We're still using
weighted rank tests. We've gotten
fancier but what the weight should be et cetera, et cetera. But you're absolutely right, that is that
the variability of the standard gets bigger with time. It must be so unless you have all patients
in day one and follow them all till two years.
Then the variability would be much tighter, but that's not the way
clinical trials happen. So that part
just happens, but it is tempting. Our
eye just tracks that way but you have to remind yourself the number of events
is small, the standard of error is large and the best comparison that we know
if in fact, is the log rank test or weighted rank test in general but the log
rank test is the one that we all are familiar with and use because of its
properties.
DR.
KRUCOFF: Thanks. So I mean, from my perspective, one
suggestion to the sponsor group that would be helpful would be to do the one
thing as was done in the effort to get the data on patients who were withdrawn
to at least for mortality, to continue to follow these folks so that at least
the basis for the data available might make clearer where the reach of those
boundaries actually lies since at this point some of that is just plain going
to be vague.
DR.
BRISTOW: I might point out one
thing. In ultra-advanced heart failure
the curves usually come back together, i.e., rematch, i.e. CONSENSUS I, i.e. a
trial we just finished; good treatment effect and then come back together. So you don't -- you know, you delay things
and so forth but in a really sick population, ultimately curves are going to
come together.
DR.
KRUCOFF: Agree, everybody dies. On the other hand, I think in a device which
is driving the ventricle, I think to at least adopt some sort of follow-up
point where we might actually see the whole cohort at some sort of time would
be a reassuring piece of information.
DR.
BRISTOW: Sure.
DR.
KRUCOFF: Okay, the last thing that I
wanted to touch on is -- which to me is a very critical piece that I am
scratching my head over is, what is the defibrillator really doing here,
because we already know that the biventricular resynchronization therapy makes
patients walk a better six minutes, changes their heart failure class, makes
them feel better and if we go to the litany of an outcomes end point from a
patient's perspective, is what do patients want as two-thirds was said this
morning, to live longer and to feel better, the third part that we usually include is and to avoid unpleasant
experiences. So in putting in a device,
the shift here obviously, is from -- as was specifically mentioned right after
lunch -- is to a patient cohort in who a defibrillator might not previously
have been considered indicated.
Now,
we're already all dealing with particularly an ischemic low rejection
faction. Could you make a case that
actually all these patients already have an indication for a defibrillator, in
which case why do you need to drop that from the indications for use if on a
MADIT II basis, you know, these patients all could be considered to already
deserve a defibrillator. You don't need
to fight this battle quite the same way.
But I really am concerned that a lot of the data -- and again, putting
aside all the issues of what's a hospitalization and what's a
rehospitalization, really imply in terms of counting toward the
hospitalizations from the patient's perspective.
To
come back for a lead revision, to have a three-hour procedure instead of a
one-hour procedure, from a patient's perspective, this is all felling better
and/or avoiding unpleasant experiences. And what is the value of the
defibrillator to me is the least discussed point of the day and to me one of
the most important issues.
DR.
BRISTOW: Right. I think this is -- we have a reasonable
answer to this. I don't know if it's
still accepted or not but basically the value is you reduce sudden death and so
you add that to the pump failure death reduction and you get these survival
curves where you get an increment of additional benefit which is now robust
enough to be statistically significant.
And so this becomes, in my mind, a discussion between the doctor and the
patient. How important it is to eek out
an additional survival benefit, vis-a-vis, a more complicated device, vis-a-vis
getting shocked once in awhile maybe.
These are all discussions that have to occur.
If
the only issue is quality of life, you're absolutely right. The CRT-P device does all of that.
DR.
KRUCOFF: Well, we really don't know
whether just CRT therapy -- we do know CRT therapy makes patients feel
better. What we actually don't know at
least from the approval-based data is whether it makes them live longer.
DR.
BRISTOW: Well, there's a survival curve
in CRT-P. It's not statistically
significant but it's a 24 percent reduction in "all-cause" mortality.
DR.
KRUCOFF: Right, and you know, for
better or for worse, this study design was really not set up to address the
question of incremental benefits of --
DR.
BRISTOW: Differences between the
devices, right.
DR.
KRUCOFF: -- the defibrillator over the
biventricular resynchronization.
DR.
BRISTOW: Right.
DR.
KRUCOFF: So I guess my other question
is, can -- do you all have any data you can share with us on the incremental
morbidity procedure duration time, technical complications associated with the
defibrillator platform --
DR.
BRISTOW: Yes.
DR.
KRUCOFF: -- because a lot of them have
been put in or were put in in the initial stage compared --
DR.
BRISTOW: So here we are with --
DR.
KRUCOFF: -- to just the CRT-P group,
just from a procedural morbidity component.
DR.
SAXON: Yeah, so as I wait for that data
broken out that way, which I don't have available, I would just say, as long as
we're talking patient scenarios, it's actually not an additional three
hours. You're putting in an RV lead
anyway. The morbidity potentially is in
the defibrillation test but, you know, that's a very controlled situation and
while it might be a difficult discussion to have with a patient, you may have
some incremental morbidity or potentially mortality associated with the device.
There's
also nothing less tragic than implanting a patient with a CRT-P device, having
them feel better, do more, only to have them die suddenly at a time when their
quality of life is for the first time better.
And one can always turn off the shock piece of the device. If you encounter that unusual patient whose
heart failure worsens, they get into the spiral secondary VT events. But I would argue that that can be discussed
at multiple times after the device is in.
You can always disable that therapy.
You can't save that patient who had the sudden death outside the
hospital with the CRT-P device.
DR.
KRUCOFF: Okay, so standing back and thinking
about how we're really going to treat patients if these data were taken as
reasonable assurance, let me just ask any of the clinicians in the group, I
mean, do you walk away from this study with the feeling that actually
Resychronization Therapy Pacing is in the future going to be malpractice, that
actually anyone who warrants -- who has an EF that low, who has a QRS that wide
that basically what they warrant is a combination CRT-D?
DR.
SAXON: I'll let everybody weigh in but
my tendency is certainly to reach for the CRT-D device but these are
individualized discussions with patients according to the severity of their
illness and their strong preference and I don't think we can make blanket
statements. I certainly don't think
it's malpractice.
DR.
KRUCOFF: Can you tell me who you would
put a CRT-P in?
DR.
SAXON: Sure.
DR.
KRUCOFF: Can you give me an example?
DR.
SAXON: Sure, there are some patients
who you have the discussion with and they don't want -- they don't want a Class
IV patient, for instance, advanced.
They don't want any issues related to -- they want to feel better alone
and they don't want to have the sudden death discussion or entertain the
thought of a shock. That's a minority
in my experience coming from the EP.
Okay, maybe it's not in others but to get to the adverse -- so I think
there are select patients, either from patient preference, there are some very
cachectic patients who are 60 or 70 pounds, who you think twice about even a
subpectoral implant. That's again, a
rare event but that would be another instance.
So
related to adverse events by type of device, there don't appear to be a
difference between Aes, whether they had a CRT-P or D.
DR.
KRUCOFF: ARE complications or ARE
observation and complications?
DR.
SAXON: ARE combined.
DR.
KRUCOFF: Combined, how about
complications?
DR.
SAXON: Sorry, no breakout according to
the device.
DR.
KRUCOFF: No breakout. So --
DR.
SAXON: Let me get back to that. I do know what deaths occurred during the
procedure and there were certainly no deaths, procedural deaths due to defibrillation testing. So I can tell you that.
DR.
KRUCOFF: Yeah, but that's not --
DR.
SAXON: That's not the answer but --
DR.
KRUCOFF: Right, okay.
DR.
BRISTOW: The implant success rate was
actually slightly higher in the CRT-D group.
It's not statistically significant.
I think it was 91/87.
DR.
KRUCOFF: All right, so my last question
is, as clinicians, particularly those of you who have actually put these in,
what are you going to tell a patient about their risk of a procedure when you
go through, by the time you have the failure to implant of nine percent, the
device safety-related, the patient safety-related complications, the
reprocedures, we're into about from my understanding about a 75 to 80-percent
likelihood of something imperfect happening --
DR.
WALDO: Don't forget about inappropriate
shocks for atrial arrhythmias.
DR.
KRUCOFF: Okay, I'm going to be done
after this question, Al. I'm sure our
chairman will get to you. So what are
you going to tell -- I mean, if I put in 100 millimeters of stint in a coronary
in a patient, I'm going to tell them they have a much higher likelihood that
they're going to be back in the cath lab than if I put in a 10 millimeter
stint. And that's a poor plumbing
analogy but --
DR.
SAXON: No, I understand.
DR.
KRUCOFF: But what are you really going
to tell patients? What should be in the
information a patient gets about the whole gambit of misery whether from the
procedure failing or the device needing revision that invasive or a lead or
whatever?
DR.
SAXON: Right. So what we tell these symptomatic patients in need of a therapy
that we've shown to be beneficial and save lives is that, but I also tell them
and have told them as a procedure has evolved to a much less -- to a much
higher success rate nationally than the 91 percent and as the tools have
improved and the hospitalization duration is less, what I have historically
told them and tell them now is, this is the device. This is an operation. You
accept some up-front risk and you have to, with your eyes open, accept that
up-front risk for the potential for the following benefit and I outline what
that symptomatic or mortality or morbidity or whatever benefit is. And then I quantify the risk according to
the national data and my own data of my own experience or my centers and simply
you know, do the informed consent process and I can tell you that the majority
of patients, particularly with this degree of disease severity, opt for the up
front risk.
DR.
KRUCOFF: Thank you.
DR.
STEINBERG: I'll just second that. You tell them that they're likely to feel
better overall, likely to have fewer hospitalizations, likely to have more
energy and likely over time to have potentially a lifesaving shock. And I think most of the patients with sick
heart failure appreciate that and I think if you want to look at a specific
measure of whether they appreciate it or not, you could look at a quality of
life index which takes into account the procedure, the hospitalizations early
on and the shocks that occur over time and in trial after trial the patients
opt by quality of life measures to -- in preference of having the device.
DR.
KRUCOFF: Okay, so on an average,
informed consent discussion with an average sick patient who would benefit long
term from this therapy, would you tell them they have a 70 percent likelihood,
an 80 percent likelihood of the procedure not going simply of having to come
back of having something else done?
What would -- what number would you tell them?
DR.
STEINBERG: For a procedural revision or
reimplant or something like that?
DR.
KRUCOFF: Or failure or a problem.
DR.
STEINBERG: For a technical issue, it's
probably in the five to 10 percent range.
DR.
KRUCOFF: It's nine percent failure to
implant, right?
DR.
STEINBERG: In this procedure -- in the
study but the technique has evolved over time.
So the implant success rate is now higher. The need for revision is now lower than it previously was.
DR.
KRUCOFF: So and the total misery rate
you're saying is down around five percent?
DR.
STEINBERG: The total misery index has
substantially decreased over time from the onset of CRT implantation to the
present day, substantially.
ACTING
CHAIR LASKEY: Okay, let's leave the
realm of imaginary numbers and let's finish with Dr. Somberg.
DR.
SOMBERG: I thought we were discussing
politics with the misery index. Well,
one of the advantages of being at this end of the table, besides getting a
crimp in one's neck is most of the questions have been answered. I think the most cogent point that we have
to consider is that we're talking about a CRT-D implant without the same
indications as a defibrillator and I think what's most critical there is the
mortality data. And from my estimation,
the mortality data is a very clear signal and I haven't seen anything that will
dispute the Kaplan-Meier curves that have been put up and the quality of the
data harvesting, I think is such that I don't see any inconsistencies or
problems with that.
So
I think the criteria for seeing that the data is there to change the labeling
is such but we have to remember that was a secondary end point, not the primary
end point, but we're not here to judge the study. The study quality -- and I congratulate the investigators for
initiating the study, that was very important of the sponsor to obviously
provide the resources to do that. I
think it's unfortunate that some of the -- not some the hospitalization end point
is clouded and that poses a problem.
And I don't think there's any way to get around that.
There
may be bias to introduce them, may not have been bias, it's a little
imprecise. But I think with such a
clear mortality signal and with everything in the study being consistent,
favoring the CRT-D, I'm less concerned with that. I do think the FDA reviewer is to be congratulated as well, and I
think there is an important concern here that are we trading off a feel better
reduced hospitalization, which is the surrogate for that, with the risk of
implant and the bother of it? And I
certainly think it appropriate that the agreement was such that that wasn't
going to be counted, that being the hospitalization, but I do think at some
point in the labeling that should be pointed out because maybe all physicians
are not going to spend their entire day here and knowing all of the minutia --
minor points, how is that, minor points of the protocol. But they should have that pointed out.
So
I think from a patient's standpoint, it's very important to know that when it
looks at total hospitalizations for everything, it is higher in the implant
group than the non-implant group and no one can get around that. And that's an important point to make.
But
you know, going back to first principles, you're dealing with patients and
patients, I think, fundamentally want to live longer and hopefully feel better
in that time and I do think this device offers that. Thank you.
ACTING
CHAIR LASKEY: Dr. Waldo, I know you gave
us your comments this morning but do you have some additional?
DR.
WALDO: Yeah, I do actually, if I have
the time, I would like to make a few comments.
First, I think we need to put some of this back in perspective, because
we really got involved with a lot of statistics but understandably. I don't think there was ever any doubt
about the mortality. Everyone is agreed
about that and if I read the things correctly there are already indication for
ICD in terms of mortality from the MADIT II trial and from other trials of
overt ventricular arrhythmias, not primary prevention.
The
way I read this is that the additional group that this would cover that is not
quite covered now and I think that's important to confirm that, is that it ups
the EF from 30 and made it to 35 and it also includes non-ischemic
cardiomyopathies which if I understand it correctly, don't yet have a primary
prevention indicational although the data would suggest that that might change
pretty soon. So I think that's really
the change that I see here.
It's
kind of small really and in many ways, I really think it's already out there,
the indications to do this sort of thing.
I think the second thing that is important and it's come out here many
times, that needs to be said, I think Dr. -- I would support what Dr. Maisel
said before, I mean, this whole thing is driven by hospitalization as the
primary end point and so the definition of hospitalization becomes very, very
important and we've gone over that enough to know that unfortunately it was not
handled very well in my judgment and I think I'm still not satisfied that I
understand this.
In
fact, I pulled -- if you pull the New England Journal article, it says,
"The primary end point was a composite of death from any cause or
hospitalization from any cause".
That's what it says. It's not --
I mean, that's very ambiguous in terms of what I've learned today. I think the definition that they're using is
very sensible about one day. I
understand that but I think it's been very, very confusing. So I think -- I also have to say although I
know we're not supposed to really but I think this unfortunately is missing a
big arm in this study. That is just the
-- just the device, an ICD device with optimal therapy without IV pacing, I
mean, to me the first time I saw this, that was obviously missing and I think
it would have helped us a great deal in this because -- but we'll never get
that answer, so we're stuck with what we have.
So I think the impact of MADIT II is clear.
I
think the impact of SCDHeFT is coming along so a lot of this may be moot that
we're all talking about but I think that's one. The other thing I think that's important that we haven't really
come to grips with -- come to terms with, we've come to grips with but haven't
come to terms with is the difference between hospitalization for any cause and
hospitalization for heart failure and I think the investigators would like to
consider this principally hospitalization for heart failure. That's fair enough if they did it up front
but they didn't and I think that has been one of the major, major confusions.
So
I think where to come down is still a problem for me. I mean, when I heard -- I only hear voices and I don't always
recognize the voice with the name, so I'm not sure who was saying it all, but,
I mean, that thing that we'd all like to be true is what was just said a little
while ago, that patients like to live longer.
The ICD will do it and that they like to feel better and IV pacing will
do it and were that were true we would all jump up and down and whistle Sweet
Sue but I think one of the reasons COMPANION was done is to date that's still a
question in the minds of many.
The
IV pacing issue, per se, we don't have to open up again. We all know how it helps some patients
enormously and others not at all.
There's still lots of issues, so I think we still have some problems
here and I think the biggest problem is we know what we would like but have we
seen the data to support what we would like.
What we'd like is an ICD in patients and make patients feel better in
the category we've been discussing all day.
Have these data demonstrated that definitively and without any
questions, and I think we're still left with some unanswered questions because
of the way the study was carried out.
I
think basically, I think the data really pointed to the fact that probably the
investigators have achieved what they're telling us they have but I think it's
very hard to say definitively and without question that that's what happened
and that's what's so unsatisfying about all this in my judgment. I don't know if I've helped anything or
advanced anything with these few remarks, but I still have a lot of problems
and I wish I didn't.
ACTING
CHAIR LASKEY: Well, you'll have the
opportunity to express that shortly, Dr. Waldo, so as we move closer to the
vote, but thank you for your thoughts.
There's a gathering storm here at the podium.
DR.
BRISTOW: So one issue is what are we
going to be achieving with this additional expansion of the indication? And I would direct your attention to the
sub-group analysis for mortality in the non-ischemic cardiomyopic group which
was 44 percent of the population which would not currently be covered with an
ICD indication or CRT ICD indication.
And you can see the point estimate indicates a 50 percent reduction in
mortality with all the caveats around sub-group analyses. It's not really statistically different from
the ischemic but you can see where that point estimate falls. The non-ischemic data, indeed, we're very
robust in this trial.
DR.
BOEHMER: If I may add, as a heart
failure cardiologist, this is a world different from MADIT II. MADIT II had a problem with worsening heart
failure hospitalization, a serious problem.
I'm not sure exactly why that was.
This has been expounded upon in many discussions. This did not -- in fact, this had quite the
opposite, a profound effect on reduction of heart failure hospitalization, a
profound effect on improvement in symptoms and exercise capacity. So this is night and day from MADIT II. There is absolutely no equivocation about
that.
Additionally,
the end point was set as a very challenging end point to take into account
computing risk. The definition was used
consistently throughout the population as adjudicated events. This was applied to every event that was
adjudicated. So I would argue that as
the definition stands, those events are those events and that bar was really
high.
If
MADIT II had that as a primary end point, there would be no MADIT II. It wouldn't have made it. So this was a hard trial. It was rigorously conducted. We got back and got the data and the primary
end point, I think is important and it takes into account competing risk. Once those devices were in, if they needed a
lead revision, they were counted as a primary end point. If they came back with a shock, they were
counted as a primary end point. So
that's taken into account.
DR.
KRUCOFF: One of the things we're stuck
with, though, is that adjudication in this trial simply could not be
blinded. So understanding that's
nobody's fault.
DR.
BOEHMER: As in any similar trial, which
is why -- which is why it was even more important to take the most verifiable
end point of "all-cause" hospitalization and "not cause
specific" hospitalization as your
primary end point. We counted every
hospitalization to the best of our ability and that's exactly what we did,
that's exactly what you have. There is
no equivocation about what that is.
That is what that is.
DR.
FELDMAN: If I could make one comment in
response to Dr. Waldo's comments; this is Art Feldman by the way, so you know
who's speaking. I think he raised a
very good point about the fact that we've -- all day we've been showing
"all-cause" hospitalization and it would be relevant to look at heart
failure hospitalization. So I'd
actually like to show that to you.
Okay, so this is the slide that we've been showing all day. This is the primary end point which is
"all-cause" mortality and "all-cause" hospitalization. You can see this risk reduction of 20
percent. Now, if you narrow it down, if
you will, to the next slide looking at now "all-cause" mortality or
cardiovascular hospitalization, you would like to see the same trend and, in
fact, if this study was as exciting and as robust as we think it is, you would
actually like to see the risk reduction get greater as you get more specific in
the end point. And, in fact, that's
exactly what happens.
Here
the risk reduction is now 28 percent and then if we go to the next slide, these
are all secondary end points for this trial, prospectively defined. This is "all-cause" mortality or
heart failure hospitalization and now you can see it's a risk reduction of 40
percent. So this is very robust data
and this is totally consistent from end point to end point to end point as we
actually got more specific. And so I
think this is very supportive of the question that Dr. Waldo was raising which
is that, if, in fact, this therapy is important, we would like to see this kind
of result on heart failure hospitalizations and in fact, we do.
DR.
WALDO: Art, if I may comment, I mean,
that's exactly my point. I have no
doubt that that's the way it is. My
point about MADIT II is that maybe I'm not quite right, but I thought that
there is now an indication from IV pacing and MADIT II patients. I may be wrong about that, but that was my
point or if it's not here, it's around the corner, that was in the report. And I think clearly MADIT II, we realized
being a MADIT II Investigator, we didn't fully understand that heart failure
problem until the light of some of these other --
DR.
FELDMAN: Yeah, I'm not sure if that's
the case but I'm going to let one of your colleagues like a physiologist answer that.
DR.
SAXON: Dr. Waldo, this is Leslie
Saxon. The labeling for the MADIT II
group does not include an LV lead.
There are two trials I'm aware of that are in the planning stages to
evaluate that type of population with biodiverse IV but there's no labeling --
there's no approved indication for MADIT
II IV. There is -- I think what you're thinking about is, there is a CMS
type coverage statement related to a wide QRS group in MADIT II, just for the
coverage of the IR ICD but there's currently no indication so, as I understand
this group that we studied in COMPANION, it's distinct without a whole lot of
overlap although some, but not a whole lot of overlap with SCDHeFT or MADIT II. Some of these patients would fall under
those criteria but as they're defined, you know, this is a much sicker group
with a heart failure hospitalization, all those other characteristics we've
talked about all day that are, you know, quite distinct.
DR.
WALDO: No, but my point is, really
what's the indication to IV pacing now?
I mean, the indication of IV pacing now, isn't it not Class III/IV heart
failure with YQRS and EFS 35?
MR.
DEVRIES: My name is Dale Devries. I'm with Guidant corporation. I'm an employee/owner. I would like to clear up one thing related
to the indication for Guidant's CRT-D devices. Guidant existing indications for CRT-D include those patients
where indicated for an ICD. When we did
the original approval on the contact CD that came before panel then subsequent
information that we provided to the FDA, that original approval was based --
did not include MADIT II patients.
However, subsequent to that point in time, we worked with the FDA
reviewing the MADIT II information as well as the information for CRT-D devices
and actually our existing indications today for CRT-D do include all patients
who are currently indicated for a Guidant ICD product. So I think that can be verified by the FDA
if anybody is interested.
DR.
WALDO: Well, not to push a point beyond
reasonableness but what is the -- I'm asking to clarify. What is the indication of simply IV pacing?
DR.
SAXON: This is Leslie Saxon again. I'm sorry, Mr. Devries clarified that
point. I was incorrect. So the indications are as you've described
them. Symptomatic heart failure on
maximum medication, EF less than 35 percent and QRS lengthening.
DR.
WALDO: Okay, and my whole point is that
if you have those symptoms and you also have MADIT II things, I would think
that you -- do you not then qualify for both IV pacing and an ICD?
DR.
SAXON: So then I would bring up the
non-ischemic group again that Dr. Bristow referred to. They would, in addition
qualify.
DR.
WALDO: Well, that's what I said before,
that this was the only group that would really -- I mean, you increased -- what
I said before, you increased the EF by five percent in the ischemic group and
then you bring in the whole non-ischemic group and I -- you know, I think that
group, I'm suggesting from the SCDHeFT data, anyway I'm sure that clearly has
to be looked at for ICDs anyway and if they meet the criteria for -- I think
we're -- I'm not -- this is not a point of contention in my opinion. I just was trying to put this into some
perspective about where we are with things.
I think we're almost there anyway.
I just wish that some of the data here were -- I don't think contentious
is the word but statistically it's been -- we've spent the whole day on
statistics really. That's why I tried
to put it back in the clinical sense right now.
ACTING
CHAIR LASKEY: No, Dr. Waldo, not
quite. We've wanted fairly far afield
and I think it's time to come back together again. So --
MS.
WOOD: I would ask the sponsor to take
their seats, please.
ACTING
CHAIR LASKEY: I'm going to suggest
simply a 10-minute break. Let's regroup
at 4:00 o'clock and we will do the thing.
So see you at 4:00.
(A
brief recess was taken.)
ACTING
CHAIR LASKEY: Okay, in the home
stretch, folks, thank you very much.
Moving onto Ms. Wood reading the question and/or projecting them. Do you want to just project them?
MS.
WOOD: No.
ACTING
CHAIR LASKEY: Okay.
MS.
WOOD: Please comment on whether
modifications to the hospitalization definition impact the interpretation of
the primary end point.
ACTING
CHAIR LASKEY: Okay, I'll do my best to
summarize the consensus or lack thereof of today's panel discussion reminding
everyone again, that the primary end point here was the composite
"all-cause" mortality in hospitalization. The modifications that we're referring to occurred on several
levels. I think the -- if I can
summarize at least the panel's conclusions with respect to the modifications of
the definition, is that the overall feeling is that it probably did not impact
adversely on the primary end point efficacy determination. We are certainly not happy with the lack of
the total body of information potentially available that goes with the term
"hospitalization", but dealing with the information that we currently
have, I guess we're coming down to the clinical interpretation of the primary
end point and that it was not adversely effected.
You
know, again, chime in to modify my consensus statement.
DR.
MAISEL: I disagree with that. I think that the -- a number of the things
that we discussed including the changing definition, the analysis of data prior
to adjudication, the large number of withdrawals despite an excellent effort to
account for those patients, I think does impact on our interpretation of that
end point.
DR.
WALDO: Who was that, please?
DR.
MAISEL: Bill Maisel.
DR.
YANCY: This is Dr. Yancy and I take the
opposite perspective. I do not think
that the modification of the definition impacts importantly on interpretation
of the primary end point.
DR.
NORMAND: This is Dr. Normand. I actually do think it impacts on the
definition and interpretation of the end point.
DR.
SOMBERG: How are you going to reach a
compromise with those statements?
DR.
KRUCOFF: So is the conclusion we're
divided?
DR.
ZUCKERMAN: (Inaudible)
DR.
WALDO: I can't hear you.
DR.
ZUCKERMAN: This is Bram Zuckerman from
FDA and we're talking about question one and there seems to be a difference of
opinion which is fine, that's why we're gathered here today. You know, certainly some panel members feel
that the changes in hospitalization definition have impacted their ability to
make conclusions about the primary end point, but is that in a qualitative way
or is that in an absolute quantitative way when we go back to the analogy of
looking at the Kaplan-Meier curves, and certainly if you want to just use the
log rank test, you could conclude that the two curves are different.
However,
given some of the problems with the conduct of the trial, the precise estimate
of how much the curves differ may be in question. In this circumstance, the panel members who've indicated that
they think there is an impact, are they referring to a quantitative impact or
even the qualitative recognition that there is a difference between the two
curves?
DR.
NORMAND: This is Dr. Normand. I believe the analysis that we presented are
correct. My point of departure is what
was included and characterized as "all-cause" hospitalization. So that's the problem that I am raising in
terms of what's counted as "all-cause" hospitalization. The data that were presented, I believe the
differences that are there.
ACTING
CHAIR LASKEY: We also heard from both
sides of the street that the log rank is a fairly robust form of analysis and
allows for tremendous leeway. And that
despite the limitation of the data set, you were still able to demonstrate a
significant benefit. Now that does not
excuse or exonerate the changing definition or the lack of the complete data
set, times and so forth, but it's a terribly persuasive argument that despite
these limitations, you're still able to demonstrate a benefit and I guess up
here, it always comes down to clinical versus statistical with all due respect
to our statistical colleagues. Dr.
Somberg?
DR.
SOMBERG: John Somberg. I would suggest potentially wording the
resolution or the question which we vote on differently and that is that there
are substantial problems with the hospitalization redefinitions. But even despite these substantial problems,
that the -- looking at absolute mortality, looking at the other secondary end
points, and looking at combining re-volt with hospitalization since all the
results seem to be going in the same direction and the mortality is the most
clinically meaningful, that the problems, which are substantial with the
hospitalization end point, are still overcomeable and that the study still
leads to substantial clinical observation.
ACTING
CHAIR LASKEY: Well, that helps us with
question number two, but we need to help the agency with question number one
and I think somehow we're going to have to -- we need to give them an answer
because this will go forth with additional trials, I'm sure. Mitch.
DR.
KRUCOFF: Well, it sounds like there may
be some variation, but if quantitative is really being able to distinguish with
some degree of precision to what degree there is a reduction of an end point
and qualitative is just -- isn't really better, then from my perspective, I
think there's a major problem in the former to feel precise that you could tell
a patient, "This is going to reduce your likelihood of being back in the
hospital in the next 180 days by X percent", I think these data would be
very difficult to feel certain about.
ACTING
CHAIR LASKEY: That's not what this
question asks.
DR.
KRUCOFF: Well, okay. I guess I'm trying to respond to Dr.
Zuckerman's question, which I take it was a part of the interest in this
question. I just don't see the curves
flipping or that -- I don't see any evidence that suggests the conclusion that
there's a real difference here would go away.
DR.
ZUCKERMAN: Dr. Laskey, I think there's
a little bit more to this question that we're trying to tease out besides
what's written on the printed page.
We've heard a difference of opinion regarding the importance of the
modifications to the hospitalization definition and we're just trying to tease
out a little bit more what the real clinical impact of that was as perhaps
expressed by Dr. Krucoff.
ACTING
CHAIR LASKEY: Yeah, Jeff.
DR.
BRINKER: I think that you're right,
that the wording of this question is devils into details. I think most of us would agree, I hope, that
if you look at that question specifically, that the modification --
modifications that occur are so important, the issue is whether the original
definition of hospitalization was very good or adequate to address the issue of
that specific indication at the very end.
And I don't think the modifications did anything to strengthen it or
make it weaker, so that's an easy answer to that question. I think the real problem will be are we
satisfied that hospitalizations, using that term as loosely as it is defined,
is -- was meaningfully -- clinically meaningfully reduced in the device group
of patients. I think that -- and we'll
have debate about that but I still don't think that that will change our view
about the end point of this entire discussion.
So maybe we shouldn't get hung up on this and just go ahead.
ACTING
CHAIR LASKEY: Probably as a practical
matter, though, one thing that I struggle with throughout the day is when these
ongoing modifications occur, are they strictly -- should they be strictly
considered amendments, or should they be approached as protocol
amendments? When this comes up in the
future, if it should, should there not be officially protocol modifications and
amendments and so forth. Is that an
appropriate way to get out of trouble at this level?
DR.
ZUCKERMAN: Yeah, I think the sponsor
and other sponsors are aware that the -- in the future, the FDA needs to be
notified through the five-day notice program or other mechanisms but you know,
the point is that we have the data as they are right now today.
DR.
SOMBERG: Why don't we just vote on the
motion as it stands?
ACTING
CHAIR LASKEY: It's not a motion. This is just a question. I guess maybe I should rephrase the response
now that I've heard the rest of the opinions is, is that -- generically
speaking, if you modify your end point after the trial is launched, that
certainly impacts the interpretation of the primary end point. However, what we've heard today does not
appear to be persuasive enough to modify our clinical sense that the primary
end point has been met.
This
is certainly not a prototype of how to conduct a clinical trial, I think we're
all uncomfortable saying that.
MS.
WOOD: Let's go to question two. Please comment on the impact of
modifications to the hospitalization definition on the interpretation of the
secondary end point and mortality.
ACTING
CHAIR LASKEY: Well, Dr. Somberg, you
eluded or just mentioned it specifically, so if you could just reiterate.
DR.
SOMBERG: Well, to summarize, I don't
think it effected the primary end point of mortality, I mean or the end point,
the secondary end point of mortality, which in my mind, is the primary -- of
primary importance.
ACTING
CHAIR LASKEY: It seems to be what the
panel is most comfortable reaching consensus on but realizing that looking at
hospitalization as an isolated end point, we would agree that because of the
competing risks, it's hard to strictly analyze the hospitalization alone in
that context.
DR.
KRUCOFF: The only other caveat, I think
being that it -- while I agree, I think there's agreement on mortality, where
it's coming from, whether it's from the resynchronization or the defibrilator
or both or how much, I think we don't have a --
ACTING
CHAIR LASKEY: Right, and we can't
answer that and hopefully we will touch on this again, because that relates to
the key arm of this.
MS.
WOOD: Number 3, are the data from the
COMPANION clinical trials sufficient to support any expanded patient population
for the sponsor's CRT-D devices?
ACTING
CHAIR LASKEY: Well, the expanded
patient population here refers to that from the CRT precedent in addition to
the life-saving aspects of the defibrilator therapy in patients with EF's 35
percent or less, et cetera, et cetera, YQRS.
I mean, are we all pretty much in agreement that the COMPANION provides
data to this -- to answer this question?
I think that is what the patient population was.
DR.
SOMBERG: Yes.
DR.
KATO: Yes.
ACTING
CHAIR LASKEY: Thank you. Anything you're uncomfortable with? All right, Number four.
MS.
WOOD: With respect to statements and
the indications for use regarding the primary end point, are the data from
COMPANION sufficient to support claims based upon the primary end point
results?
ACTING
CHAIR LASKEY: Some of us think so, some
of us think not. We may need to resolve
this by who votes which way. I'm not
sure in this discussion we're going to answer that in greater depth without just
rehashing everything that we've discussed.
There is clearly a limited data set to address the "all-cause"
hospitalization part of this and we don't know if we can go further than that.
MS.
WOOD: Part B, of so, please comment on
whether the language of the proposed indications for use statement adequately
describes that end point. In
particular, please discuss whether the terms "all-cause"
hospitalization is appropriate.
ACTING
CHAIR LASKEY: Well, we seem to be
asking the same question repeatedly and I hate to sound monotonous but you'll
get the same answer which is there's clearly a division of opinion here. Hopefully, you'll get a consensus by the end
of -- I know you'll get a consensus by the end of the day.
DR.
WALDO: But don't you think it would
help to put a definition in there. If
they're just going "all-cause" hospitalization?
ACTING
CHAIR LASKEY: I'm not sure we can put a
definition in after the trial was over.
DR.
WALDO: Oh, but the definition that they
used in the trial because, I mean, if it's the COMPANION data that we're
talking about, let's at least use the specific definition for what
"all-cause" hospitalization means so there's no ambiguity.
DR.
ZUCKERMAN: Yes, to help you, Dr. Waldo,
I would refer all the panel to Section 4, page 2 of Dr. Faris' review where the
-- right after the term "all-cause" hospitalization is listed, the
sponsor does have their current definition.
DR.
WALDO: Okay, that's perfect then.
ACTING
CHAIR LASKEY: We haven't heard the word
"perfect" yet today, so --
all right. Everybody happy with that?
DR.
WALDO: Definition has been so important
in what we're talking about all day.
ACTING
CHAIR LASKEY: All right, well, it is
specified in the protocol. Yeah.
MS.
WOOD: Number five, with respect to
statements in the indications for use regarding the secondary end point of
mortality, are the results from the COMPANION clinical trial sufficient to
support a mortality benefit claim for the sponsor's CRT-D devices in the
COMPANION population?
ACTING
CHAIR LASKEY: I think the answer here
is a resounding yes.
DR.
KATO: Yes.
MS.
WOOD: Number six, please comment on
whether the CRT-D labeling should characterize the total number of
hospitalizations and length of time patients spent in the hospital for the
CRT-D and OPT arms of the COMPANION trial.
ACTING
CHAIR LASKEY: Well, we certainly
discussed that this morning, I guess.
It's an arduous amount of work to put this into the label and whether it
adds any meaningful information, let's just hash that out. John.
DR.
SOMBERG: I think what should be put
into the label is the implant hospitalizations as well. There should be some point where it is
understood that if one includes implant and implant related hospitalizations,
that "all-cause" hospitalizations do equalize and that that shouldn't
be somehow hidden under the rug.
DR.
WALDO: So then we lose a lot of the
impact of the primary end point.
DR.
SOMBERG: That's exactly right. So it's up to the physician to understand
just what was talked about all day here.
That you take risk up front and you trade that off for this surrogate
steel ventilator on which is a reduction in hospitalizations but the trial was
specifically designed and agreed to that that wasn't going to be taken into
account but that is something that should be noted to the patient because it's
important for the patient to know in the -- I'm sorry -- this has a mind of its
own, it keeps changing its height.
But
just to very quickly summarize that, I think it would be useful for the patient
to know and for the physician to be aware of that as well, that the implant
hospitalization impact on "all-cause" hospitalizations and that if
it's not clearly said someplace in the labeling would not -- will not be known
because I remember reading the COMPANION study and never thought of that when I
read the COMPANION study and therefore, maybe I was an uninformed person and I
at least took the opportunity to read that study.
DR.
WALDO: Yeah, and again, I remind you
that the definition in the COMPANION study I read the sentence, it doesn't --
it just says "all-cause" hospitalization. It's terribly ambiguous really in the end, although it's very --
what's spelled out here is very clear and sensible, it's not clear -- it's not
intuitively obvious when you read it from the paper.
ACTING
CHAIR LASKEY: That, of course, is the
answer to the next question but to stay with where we are on Part A, which is
whether the labeling should characterize total number of hospitalizations and
length of time patients spend in the hospital, do we agree to that, number
one. Do we suggest that, number
two. Number three, if we do either one
or two, it needs to be adjusted for the fact that there are different numbers
of patients in the two -- you had twice as many patients in the device arm as
you did in the control arm. So that
needs to be normalized, if you will, but what's our advice to the agency on
changing the labeling to include total number of hospitalizations and --
DR.
WALDO: And maybe even add something
about competing risk because that point was very well made also.
DR.
YANCY: Warren, if I can speak to this,
I think so that even though I don't support the persuasion, but just so that we
can have some internal consistency, if ther are those on the panel that are
uncomfortable with the hospitalization data, that I think it is certainly
inconsistent to attempt to quantitate it and put it in the label.
DR.
NORMAND: Well, if I can make a
suggestion, I would quantitate it in the way that I would have liked it at
least defined and at the very least, I would include Part B. So I don't advocate putting total number of
hospitalizations because of the adjustment that's necessary and I think that's a
little bit difficult to translate. But
I do think and I'm sorry, I can't separate A from B, but if I didn't put -- I
don't think it's necessary to put A, but I would put B and I'd put B in, I want
the subsequent hospitalizations for the implants to be put in there.
DR.
ZUCKERMAN: And the way that I would
address that is that I would make it clear that there is a requirement for
implant hospitalization. So something
as simple as a phrase that says, "All-cause" hospitalization apart
from implant hospitalization" would capture that.
DR.
KRUCOFF: I would also vote for really
starting with what would you really want a patient to know and that is, I think
it was actually stated quite well earlier, this is a procedure that requires a
hospitalization. There are risks to the
procedure that include you might have to come back into the hospital at a later
time and there are some ball parks as to what the likelihood of those risks
are. That the benefit then that has
accrued in this data is that there may be a change in your likelihood of
rehospitalization without knowing exactly how much and that you may not
die.
So
I think in the same way you would talk to a patient about it, I think putting
some sort of ballpark language and numbers together would be quite reasonable.
DR.
WALDO: Very well stated, may I suggest.
DR.
BRINKER: Well, Bram, maybe you can help
me. The indications are primarily to
the physician, is that not correct?
DR.
ZUCKERMAN: That's correct.
DR.
BRINKER: I mean, we're not writing a
patient pamphlet. We're writing
something that the physician can use as a guide to whether this device is
appropriate in his particular patient.
And quite frankly, I'm very unhappy with the way hospitalization has
turned out, the say it's being configured.
I think people go home, they may find a more meaningful result to
express but I'm not absolutely positively sure that the way it's expressed
right now in terms of single -- primary hospitalization, the first one, is the
best way of determining whether a patient truly benefits from this in terms of
overall hospitalization over the duration of his device.
I
think it is, and I think if you look at the data carefully, you can tease that
out. I also think that that would take
away the issues about readmission or pacemaker changes like remanipulation, et
cetera and would allow you to even include the primary hospitalization for the
device implant, because I do think it will work out but I also think that we're
definitely convinced that the mean issue here, that is whether COMPANION
patients should have this device indicated is agreed to and the impact of
mortality is agreed to. I think we're
really focusing now, maybe too much time on wordsmithing the benefits of the
primary end point and how best that can be expressed.
DR.
ZUCKERMAN: All right, let me clarify
that. We're not here to wordsmith very
sentence in the label but we are -- the
FDA and sponsor are looking for general guidelines, and I think the general
guidelines are the following. Dr. Waldo
made the statement that you know, in a New England Journal article as
well as in other available information, information about the device implant's
success rate, complications, number of returns, isn't readily available. We'd like to provide in a -- in our clinical
summary relevant data to the physician.
I think we saw, for example, a table that just lists the implant data,
which goes a little bit farther than Dr. Yancy's statement and I'd like to have
some panel input on that but by the same token, we're by no means asking that
we're asking the panel at this point to rewrite the primary end point to
include in the primary end point all those initial hospitalizations.
We're
just asking what supplemental table would be helpful. It sounds like some more information about the initial implant
hospitalization problems in perhaps tabular form simply stated could be of help
to physicians.
DR.
KRUCOFF: Yeah, and Jeff, just to take
one point, I'm not saying we should -- it should be written like in a form of
consent document, but I think if we structured the information to the physician
so that it would be digestible in a way that they could turn around and talk to
a patient, meaning like I think the syntax of how that information is presented
could be useful in the way it's presented.
DR.
BRINKER: All right.
DR.
SOMBERG: You know what you were saying,
mentioning, I agree completely and I think it's very important to realize that
if we just -- if we do recommend to the FDA to balance the hospitalization data
which has certain potential flaws in it, with the observation that if you
include the initial implant hospitalization and all other revisions, then the
two are equal. We don't have that
balance, I don't think that would be picked up by the average person who's
going -- the physician, not patient, the physician who is going to make use of
this and therefore, it's an important addition and it's just as important as
the mortality and just as important as the combined end point because it leaves
the whole label incomplete.
DR.
BRINKER: Well, my only problem is not
the balancing act because I believe these other pieces of information that
we're talking about should be somewhere in the labeling, not necessarily in the
indication portion. My problem is
leaving in the indication portion the statement that appears -- the proposed
statement that appears with regard to "all-cause" hospitalization and
"all-cause" mortality. I'm
not comfortable with that statement and balancing it off by putting in the
other pieces of information about implant requirements and need for a
replacement and all this other business.
While I think it's important, I don't think that belongs in the
indication section.
I'd
be happy with the second two things in the indication section and leaving out
the hospitalization business or I would be happy if there was some other review
of the hospitalization to see if it could be expressed in some other way. I'm just unhappy about the way the
hospitalization statement is read and what it's based on.
DR.
ZUCKERMAN: I think we previously
answered the question from Dr. Waldo referring to italicized text that defines
hospitalization. And I'm wondering if
it's not possible to simply add another bullet to said text that captures the
query and the concern about implants and revisits. I really believe the issue of simplicity is where we should
target and I support what Bram just mentioned, but I'm wondering if there's a
simple way we can do this so that it's not confusing.
ACTING
CHAIR LASKEY: Well, probably the
simpleness way is just to have a separate table of the events related --
surrounding the primary implantation without basically coercing the sponsor to
redo the primary end point with the inclusion now the penalty for getting the
device, which I personally think is unsupportable, to penalize that arm. You can't get in that arm without having the
device, but I think it's certainly an
appropriate place in the labeling to indicate to all physicians, whether
they're implanting these or not, that there is an up-front risk as well as
benefit with that index procedure.
That's one man's opinion.
DR.
KATO: I think the one other issue with
the hospitalization question is that as was identified earlier, you know,
hospitalizations for, you know, fixing the device, replacing the leads,
whatever, have gone down. And so to
some degree the hospitalizations that are going to occur with the implantation
of the device are going to be positioned -- there's going to be certainly that
component and as a result, certainly that variability.
In
some physician's hands, they may not have hardly any hospitalizations and other
ones may have even perhaps double the rates of what we've seen in the companion
study. And along those lines of being a
surgeon, I think the hospitalization definition is difficult enough and because
of the variability in the daily practice, I'm not even sure a comment should be
made, you know, one way or the other about it.
It's a device. A procedure is
going to be required and I think patients know that. I think that's part of the informed consent discussion that takes
place between a physician and a patient but I think getting into that kind of
writing that or advising the FDA in terms of all the -- and the sponsor in
terms of an actual label, I think is going to be very, very difficult.
DR.
SOMBERG: The problem is when you look
at the data, it's very impressive towards hospitalization reduction but when
you add that in, it reverses. So unless
there's going to be some sort of very dramatic change in user abilities, that's
not going -- so that balance has to be there.
And I'm just afraid if you mention -- if you just mention
"all-cause" hospitalization is markedly reduced and we all know that
the problem is with statistical problems we have with hospitalization, you have
to mention a bullet point. And it could
be a very simple one. I don't know if
it has to be a table even, Warren, but just a statement that there is an
equalization of the two groups when that implant time is included.
DR.
MAISEL: Warren, can I suggest a little
wording potentially? That the Guidant
CRT Defibrillators have demonstrated the following outcomes in the indicated
population specified above; one, reduction in risk of "all-cause"
mortality, two, reduction of heart failure symptoms, three, reduction in
post-implant hospitalization rates and then in parenthesis but not necessary a
reduction in total hospitalization rates.
DR.
YANCY: You know, I'm going to be of
sort from here, but you know, we're talking about a real world application now
and when implanters and clinicians are talking about hospitalizations and
someone with heart failure, it really is a given that you've got to put the
device in. So what everybody wants to
know about is what happens after the fact.
I
think that part of what you said, actually I agree with, but I think to massage
this further, this really obscures the information.
ACTING
CHAIR LASKEY: I'd go further and say to
taint it is not helpful.
DR.
BRINKER: Well, the only reason for this
is because there's a -- I mean, I feel at least some discomfort with the
calculation of hospitalization and I would like, actually if you can't do
anything better -- and it's a relatively small point, I think. Like everybody said, this device is going to
be used for all the reasons that people say.
I would just not like to give my seal of approval that this device
decreases the need for hospitalization based on the data that was presented
today. I agree it should be put in, in
this population. I just would withhold
that, that's all.
ACTING
CHAIR LASKEY: Put in for what reason?
DR.
BRINKER: For all the reasons that have
been expressed. I mean, number one, I
don't like the idea that we haven't incorporated all the issues involved in the
device hospitalization, including rehospitalization for things like
reimplantation when the first implant is not successful. The fact that one could, by the very
definition of time frame of hospitalization, have come up with different results,
we don't know that because we don't have a track on that, but it's quite
possible that if we put -- included same day hospitalization, then lead
revisions and all those things would have shown up as hospitalizations. And there's still some doubt whether the
change in the definition of time for hospitalization in some way impact
non-implant hospitalizations that may have occurred. So because of all these things I just have a little unsettled
feeling about that particular end point.
ACTING
CHAIR LASKEY: Well, perhaps we can help
you along as we answer number seven.
DR.
ZUCKERMAN: Okay, but Dr. Laskey, can
you -- we've heard a lot of opinions right now on question six. Would you care to summarize? Is the general spirit to put the data on
implant hospitalizations in the label?
I think we've gotten off on a tangent when we're talking about what
potential indications for use are.
That's a separate story here or would you summarize where we are for
six?
ACTING
CHAIR LASKEY: Well, the IFU is a
separate issue although we seem to have achieved consensus on that. That's distinct from whether the labeling
should characterize the total number of hospitalizations and length of time, et
cetera, et cetera. I think we're less
in favor of that than part B which is that, yes, information on device implant,
hospitalization and its sequelae, should be included. I thought we were moving towards its inclusion as a separate
table in the label but not as a mandate to revise the statistical analysis of
the primary end point. That information
does belong in the label but it should not be the undoing of the primary. I think the primary end point has enough --
we have enough reservations and concerns about the hospitalization piece that
is going to be reflected, I would suspect, in the labeling. But I think it's helpful irrespective of
that conversation, to certainly separate out the risks of that primary
implantation procedure in the labeling.
So to Part B, I think we're more in agreement.
DR.
KRUCOFF: One caveat that might be
useful would be to recognize that if this is a patient population in whom CRT
is indicated, that if -- we didn't see it today but if data were made available
that could differentiate what the CRT added procedural would look like compared
to what they would receive a anyway, again, from a physician's side, I think
that would be helpful in talking to patients.
Is there a difference between putting in a CRT defibrillator than just
putting in a CFT, recognizing you're going to need a procedure to have this
device put in at all.
ACTING
CHAIR LASKEY: Well, again, we weren't
allowed --
DR.
KRUCOFF: We didn't see that today.
ACTING
CHAIR LASKEY: It's hard to imagine in
real life how this will be separated out.
People will view this all as a single entity but our job today has been
really delimited by the insistence on just looking at the two arms.
DR.
YANCY: But just to buffet the last
question, I'm not an implanter but once the CRT platform is in, all the
necessary hardware there to facilitate the CRT-D application and so
theoretically if there are any risks they are incredibly small. So I'm not sure if I would leave that as a
lingering major concern.
MS.
WOOD: Number seven, please comment on
whether the CRT-D labeling should present adverse events for the CRT-D and OPT
arms of the COMPANION trial in a consolidated manner that would allow their
comparison.
ACTING
CHAIR LASKEY: We just expressed our
unanimous desire to see these ARE's reflected as a separate set of information
within the -- within the label. That
includes both the index procedure as well as any sequela.
DR.
ZUCKERMAN: Okay, I think if we go to
Section 1-13 of the label, it's apparent what one potential problem is in that
all the CRT-D adverse event information is first displayed. Then the OPT information is displayed. So you don't have a side-by -side
comparison. We're talking more about
some of the side-by-side comparisons that would be relevant here. This is on Section 3.1.
DR.
KRUCOFF: I mean, one of the things, I
think we've pointed to pretty clearly is that everything about having the
device implanted is unique to having the device implanted compared to medical
therapy. I think but what to me is a
real world issue is that a large percent of the practice in this patient
population would now say medical therapy once you've reached OPT, it's time for
a device. So how do you characterize
that?
If
this is came to the population who are wide QRS, EF less than 30, and
struggling on pretty optimal medical therapy, then characterizing the risk of
putting the device in is not unique to this platform other than the
defibrillator component if the defibrillator is not specifically
indicated. And we just -- we haven't
seen any way of separating those two sets of ARE's.
DR.
YANCY: Warren, on this question I would
say no because I don't think it's clinically relevant if that's what you're
looking for because it says on a side-by-side consolidated manner. It's almost a nonsensical question.
DR.
WALDO: But, you know, if you look at
the PDO, in Germany they do this all the time, I don't see any harm in it and
there might be some help.
DR.
YANCY: Well, I think the CRT-D end
tables should be there. That's just a
point of information and that's perfectly appropriate but to do it in a
consolidated manner, it's -- they're not equivalent comparisons.
ACTING
CHAIR LASKEY: Now I'm not quite sure
what that means unless it's just the template is in the PDR. Is that what you're referring to?
DR.
ZUCKERMAN: Yeah.
ACTING
CHAIR LASKEY: Or do you want to see a
pretty table?
DR.
ZUCKERMAN: Usually -- look at all the
adverse events listed beginning on page 1-13. You have the CRT-D events all
listed. Then you have the medical
therapy events all listed. Should they
be side-by-side? Are they relevant comparisons
for the clinician to look at or is this the relevant format to display them
because of Dr. Krucoff's comments that they really aren't equivalent therapies
where in your trial you are comparing these two therapies?
DR.
KRUCOFF: I'm not sure if this is
helpful or irritating, but to me the perfect table would be to see CRT-P
side-by-side with CRT-D. That would be
much more relevant, I think, in making a current decision than compared to OPT.
DR.
SOMBERG: It's a -- I must say it's a
relevant table. I mean, it's tantamount
to the placebo arm of a drug study. So
you're saying what's the frequency of something? What's -- you know, I'll give an example. Sepsis, some people have said sepsis should
go up with a device implant. Some
people say, "Oh, no, it's -- in this day and age, you'll never see
it". Doctor looks here says,
"Hey, look, in the optimum medical therapy, the incidence is zero and with
device it's 6.5 percent". Then you
know you may have a sepsis problem in the best events which is, you know, the
investigators who took part in the controlled trial, right? So I think it's worth a comparison, but that
probably should be done in almost any study.
Wherever you put any incidence, if you have a controlled group, put that
incidence in too, so that people know whether that's just happenstance or
occurs by the intervention.
ACTING
CHAIR LASKEY: Well, maybe it's
something more than stylistic. I fail
to really understand the gist of this because comparisons lend themselves to at
least to those minds some verification of what is the -- what is the
comparison, what is the nature of the
association or lack thereof? Are
there differences? So it begs a whole
other series of questions. Are you
prepared to open that Pandora's box?
You're just going to list all this stuff and all this stuff and now what
does the clinician do without some attempt to compare this list of -- it's
here. I think an inquiring mind can do
with it -- it's not -- it's fully disclosed.
DR.
SOMBERG: Well, if you put it
side-by-side, you can make a comparison.
ACTING
CHAIR LASKEY: There is a lot to put
side-by-side here, though, that's the -- we need to stratify what goes in and
not to dumb this down, but it needs some significant stratification, if you
will.
MR.
MORTON: Dr. Laskey, I agree with you
that the point is not to capture everything that we could out of study but to
put in this relatively small document what information the physician needs in
order to decide whether to treat a patient with the device.
DR.
NORMAND: I'm confused about the
question. So is the question
aesthetics? How you display it or do we
include it?
DR.
YANCY: Aesthetics.
DR.
NORMAND: I don't care what it looks
like, it should be included.
DR.
ZUCKERMAN: Okay, the question refers to
how, if someone takes the time to read this document, it will read in a way
that it will be useful and right now, there's not a side-by-side comparison of
events. There are pluses and minuses to
that sort of approach and we're just looking for a general sense of feedback.
DR.
SOMBERG: In drugs, isn't it generally
something that occurs in more than one percent of frequency is something like
that and you do have a comparison. If
you have comparative data, you put the comparison to be made. Why should that be --
DR.
ZUCKERMAN: That is correct.
ACTING
CHAIR LASKEY: Yeah, I guess I'm just
going to the next level which is just looking at numbers is not often
helpful. You want to know if they're
actually different. So --
DR.
KRUCOFF: The other thing, there is in a
small document the potential redundancy with some of the earlier
questions. If data on the risks
associated with the implantation of the device has already appeared in the
document, clearly stated, then does the additional comparison of all of these
also actually redundantly characterized individual line item comparisons add
anything to the information you're conveying to the physician or does it just
make a longer document? I just --
there's a potential for a lot of redundant information that may work reverse of
giving information clearly.
DR.
BRINKER: It's not going to make a
longer document if you put them side by side as opposed to right after each
other. I think that with the exception
of procedurally related factors, the implant procedure basically. The other thing we would usually like to see
adverse events and next to each other seems reasonable.
ACTING
CHAIR LASKEY: Eight.
MS.
WOOD: Please comment on whether data
obtained from patients after withdrawals should be used in any of the analyses
described in the device labeling.
DR.
NORMAND: I'll say, yes, given the
description that the sponsor gave to us, that this was done in a manner to
where there was no systematic difference between the collection of who was in
what arm. So actually, I view it as a
good thing.
DR.
KRUCOFF: I agree entirely. I think compared to not having those data,
that the work done to go and get those data probably yields a lot more
important information, although it brings some questions with it, but I totally
agree that it's much better than having all those blanks.
DR.
KATO: I agree as well.
DR.
YANCY: I agree, too.
ACTING
CHAIR LASKEY: Are there any other areas
you want us to elaborate on?
DR.
ZUCKERMAN: No.
ACTING
CHAIR LASKEY: Well, our schedule has us
breaking. I suggest we just surge
forward here and draw to a conclusion.
Okay? So at that point, I'd like
to have -- at this point, I'd like to have Geretta read the FDA -- wrong page,
sorry.
Open
public hearing portion. Anybody in the
audience who wishes to address the panel on today's topic? If not, I'd like to close this portion of
the open public hearing and I inverted the order here. I've already asked you if you had any
additional comments or questions before the vote, but do you have additional
comments or questions before the vote?
DR.
ZUCKERMAN: No.
ACTING
CHAIR LASKEY: I'd like to ask the
sponsor if the company has any additional comments or questions before the
vote?
DR.
DeMETS: No.
ACTING
CHAIR LASKEY: Thank you. And at this point, we can hear from industry
and the consumer representative.
MS.
MOORE: Well, I don't think there's very
much more that needs to be said. We've
heard a lot of discussion today and I'm reasonably sure if the public were
privy to this discussion today, there would be more people who would be
convinced that they must adopt a heart healthy lifestyle. But it is satisfying to know that there are
devices available that will alleviate or treat or improve the problem of heart
failure and I think it is extremely important that the patient knows what the
procedure involves and also the risks and I think from listening to your
discussion today, I believe that this will be the case.
ACTING
CHAIR LASKEY: Thank you, Ms.
Moore. Mr. Morton?
MR.
MORTON: Thank you, Ms. Moore. I think we can all take pride in the fact
that the public is privy to what goes on here and we should all be very proud
of that. The FDA did a nice job
especially in the written summary and the sponsor did a nice job in summarizing
a lot of data.
ACTING
CHAIR LASKEY: All right. Thank you.
Geretta, if you could please read the voting options.
MS.
WOOD: The medical device amendments to
the Federal Food, Drug and Cosmetics Act as amended by the Safe Medical Devices
Act of 1990 allows the Food and Drug Administration to obtain a recommendation
from an expert advisory panel on designated medical device premarket approval
applications, PMAs, that are filed with the agency.
The
PMA must stand on its own merits and your recommendation must be supported by
safety and effectiveness data in the application or by applicable publicly
available information. Safety is
defined in the Act as a reasonable assurance based on valid scientific evidence
that the probable benefits to health under conditions of intended use outweigh
any probable risks. Effectiveness is
defined as a reasonable assurance that in a significant portion of the
population the use of the device for its intended uses and conditions of use
when labeled, will provide clinically significant results.
Your
recommendation options for the vote are as follows; approval if there are no
attached conditions. Approvable with
conditions; that panel may recommend that the PMA be found approvable subject
to specified conditions such as physician or patient education, labeling
changes, or a further analysis of existing data. Prior to voting all of the conditions should be discussed by the
panel. Not approvable, the panel may
recommend that the PMA is not approvable if the data do not provide a
reasonable assurance that the device is safe or if a reasonable assurance has
not been given, that the device is effective under the conditions of use
prescribed recommended or suggested in the proposed labeling.
Following
the vote, the Chair will ask each panel member to provide a brief statement
outlining the reasons for their vote.
ACTING
CHAIR LASKEY: I'd like to ask panel
members for a motion on this PMA. Dr.
Maisel?
DR.
MAISEL: I would like to make a motion
that the PMA is approvable with conditions.
ACTING
CHAIR LASKEY: Is there a second?
DR.
SOMBERG: I'll second.
ACTING
CHAIR LASKEY: All right, I'd like to
have a condition for the PMA then.
Bill?
DR.
MAISEL: I would like to propose that
the indications for use statement be amended such that the first bullet point,
reduction in risk of "all-cause" mortality that refers to
"all-cause" hospitalization is removed so that the statement will
read, "Guidant Resynchronization Therapy defibuilators have demonstrated
the following outcomes in the indicated population specified about; reduction
in risk of "all-cause" mortality and reduction of heart failure
symptoms".
ACTING
CHAIR LASKEY: Do we have a second on
this condition?
DR.
BRINKER: I second it.
ACTING
CHAIR LASKEY: Well, we need to have
some discussion.
DR.
YANCY: I think that's the ultimate
penalty to the trial because that removes the --
MS.
WOOD: Can you talk louder?
DR.
YANCY: I think that that is tantamount to
a penalty to the trial because I think that removes one of the very most
important issues and so I'm uncomfortable with removing that from the
statement. That's not the way the trial
was designed. It's not consistent with
the pre-specified end point. I think we
had captured a flavor of identifying and qualifying hospitalization but I can't
accept removing it.
ACTING
CHAIR LASKEY: Additional
discussion? Mitch?
DR.
KRUCOFF: I basically have to agree with
Clyde, I think in spirit, but I do think what is really present here amongst
all of us pretty clearly is the concern of the counter-balance of what is the
cost up front for the benefit ultimately and should that be conveyed. So another option might be to leave the
primary end point as it was, in fact, examined and reported as a reduction in
mortality and "all-cause" hospitalization. But to -- and I don't have the wordsmithing in mind, but to
include in that wording above and beyond the morbidity associated with
implantation of a permanent device or something that sort of creates the
reality factor that there are two sides to this coin.
DR.
SOMBERG: Well, I must say Bill's motion
and the reason I seconded it is I thought it was not a penalty but it's the
clear message of what was shown and hospitalization is fuzzy. There are some issues about it and to just
gloss over that is, I think, inappropriate.
But no one is being penalized here and in fact, I think that is a very
powerful indication. It is the most
powerful and what happens if we wanted to take out mortality and just leave
hospitalization. People would say,
"Oh, my goodness, I'm not sure but you're leaving -- mortality is the
primary indication that this causes the reduction in and is also a symptom
mentioned there". It's just the
concept of hospitalizations is clouded and why should we go ahead and increase
physician bewilderment as opposed to decrease it and make it clear-cut that
CRT-D reduces mortality and improves
symptoms.
ACTING
CHAIR LASKEY: Well, this has been the
theme of the day, so should we just vote on this condition? Yes, I will restate the -- the motion, of
course, on the table is to approve the PMA with the condition that the
instructions for use be amended to remove the claim of a benefit in
"all-cause" mortality and "all-cause" hospitalization and
to just refer to the benefit for mortality, "all-cause" mortality,
and the alleviation of symptoms. Is that
correct? Can we now vote? All in favor of --
DR.
KRUCOFF: I'm sorry, Warren. Are we voting on just the condition?
ACTING
CHAIR LASKEY: Just the condition.
DR.
KRUCOFF: Just the condition.
ACTING
CHAIR LASKEY: Right. We've finally got this straight. All in favor of that language for the first
condition raise hands?
DR.
WALDO: Can I say "aye"?
ACTING
CHAIR LASKEY: That's good. One, two, three, Dr. Waldo and two, three,
four, five, six in favor. Against? Two against. So six to two. May I have
another condition for this PMA? Dr.
Krucoff?
DR.
KRUCOFF: I'd like to propose a
condition that at least mortality data be collected for the entire available
cohort out to three years.
DR.
YANCY: The purpose being?
DR.
KRUCOFF: To appreciate some of the
concerns about the low numbers at the end of those Kaplan-Meier curves and
whether their boundaries actually cross or not, just to complete that data.
DR.
YANCY: So we just voted to make
mortality the lead indication but now we have anxiety about mortality.
DR.
KRUCOFF: I wouldn't quite go that
far. I think, you know, we have a very
reasonable explanation, I think, that it's really the range of follow-up and
just the numbers. We've got patients
who have already been enrolled, who already have the device in. Where completing mortality, I don't see as
overly burdensome, but it would be nice to know if those confidence intervals,
when you really finish the data actually behave as you would -- as I would
expect them to based on the earlier observations.
DR.
SOMBERG: Can I ask a point of
information?
ACTING
CHAIR LASKEY: Yeah. We're a little ahead of ourselves. Can I just have a second for this
condition? Anybody second Mitch's
condition? Before we have the
discussion, we need to have --
DR.
SOMBERG: I just wanted a point of
information which technically takes precedence but whatever you want,
Warren. I just wanted to ask if I may,
is that being done already by the sponsor to continue with --
ACTING
CHAIR LASKEY: If I don't get a second
for the motion, some derrick comes and removes me from this spot.
Do I have a second, gentlemen, ladies?
I guess we're not going to discuss it.
Okay, for that condition.
DR.
YANCY: Is the floor open for another
condition?
ACTING
CHAIR LASKEY: The floor is now open for
another condition, yes.
DR.
YANCY: So I think another condition
should be a separate statement that describes the hospitalization experience
consisting with clinical trial results with the appropriate qualifiers and
statements of concern.
DR.
NORMAND: I didn't understand your
suggestion.
DR.
YANCY: A separate statement that
describes the hospitalization experience in the clinical trial with the
appropriate provisos that capture our concerns about the change in definition.
ACTING
CHAIR LASKEY: Second on Clyde's
condition?
DR.
MAISEL: I second.
ACTING
CHAIR LASKEY: Can we just clarify? You mean a section on hospitalization
separate from the indications or as part of the indications?
DR.
YANCY: Preferably as part of the
indications but since we've just voted that away, so this will be a separate
statement.
ACTING
CHAIR LASKEY: This will be a condition
for approval, second condition of approval to be exact, as Clyde has stated it,
so some discussion? I think it's a
great idea.
DR.
BRINKER: Yeah, I agree. I think it is a good idea. I think it should not an indication, just
emphasized and it might also invite further look at some of the things that
were brought up in question 6A about the number of hospitalizations and the
duration of hospitalization which I personally would like to see.
ACTING
CHAIR LASKEY: Appropriately displayed,
adjusted for differences in patient numbers and so forth, right. That goes without saying.
DR.
SOMBERG: You said adjusted for --
ACTING
CHAIR LASKEY: Well, twice as many -- I
mean, we keep going around it, so just asking for numbers of hospitalizations
or event rates, when there's twice as many people --
DR.
SOMBERG: Sure.
ACTING
CHAIR LASKEY: -- in the one arm, so
let's get the language out there.
DR.
KATO: So this is just going to be a
narrative, not within the indication section, correct.
ACTING
CHAIR LASKEY: This is not within the
label or the indications for use. This
is just our list of conditions for approval of this PMA.
DR.
KATO: Okay.
ACTING
CHAIR LASKEY: So this has to go
somewhere. Okay, a third
condition?
DR.
MAISEL: Did we vote on that one?
DR.
ZUCKERMAN: Okay, before we vote on the
second condition, Dr. Laskey, can you and Dr. Normand just further describe
what you envision -- you envision in the clinical trial section, a discussion
of the hospitalization information, the pros and the cons that occurred in this
trial. Would you also, Dr. Normand,
include any statistics with that or how detailed would you comment on the
Kaplan-Meier curves for hospitalization and the primary end point?
DR.
NORMAND: Well, I think the issue is
that with the caveat, with the hospitalization measured in the way it was just
described, I think it's a little -- I wouldn't want to break it out. I'm not sure what P values I'd want to put in. I think I probably would like to think a
little bit more about it just because of what's included and what's not going
to be included. I think we're still not
clear on that.
ACTING
CHAIR LASKEY: The problem is, and we
know where Dr. Yancy is coming from here, the problem is going to be to assign
statistics to this information when we've been speaking all day to the
competing risk aspect, that they may not be meaningful or interpretable. But clearly this information belongs in
there.
DR.
YANCY: There is one specific way to
capture that, Bram, because since we've made it appropriate to take secondary
end points and put them in some position of importance, let's use the heart
failure hospitalization data for which there should be very little argument. Heart failure related hospitalization, the
data do exist. We've seen it today and
they are consistent with a clinically important question when one utilizes
these devices.
DR.
SOMBERG: But you -- I would think you
would want to put the "all-cause" hospitalization data in. You would want to also put the heart failure
data in. And you would just want to put
a caveat that there are some problems with the hospitalization considerations;
A, statistically. You don't have to go
into detail, but in changing the definition.
That introduces some uncertainty.
And B, of the procedural hospitalizations may be of consideration as
well. But I think those are just
concerns that should be put in some place, but they don't have to have equal
weight and one does not have to go into a complete discussion of what we did
today on the panel, because it will have no weight then.
DR.
WALDO: I agree, and also something
about competing risks again ought to be a part of that.
DR.
KRUCOFF: An unblinded adjudication, you
know, ultimately heart failure hospitalizations are an unblinded -- a
relatively unblinded adjudication.
ACTING
CHAIR LASKEY: Well, it can be stated as
such, but I think it belongs in there.
I would agree with this condition but starting with "all-cause"
and then drilling down, if you will.
DR.
YANCY: I think something akin to what
Dr. Feldman presented would be a correct way to display it,
"all-cause", cardiovascular, heart failure related. If we are going to capture it, that would be
the right way to do it.
ACTING
CHAIR LASKEY: And let's not forget the
information on the index procedure for device implantation is capture
elsewhere. We've asked for that to be
put elsewhere in the label.
DR.
YANCY: That's correct.
ACTING
CHAIR LASKEY: So now may we vote on
this condition? All in favor of a
supporting separate statement regarding the hospitalization data with the
appropriate caveats. All in favor of
that.
DR.
WALDO: Aye.
ACTING
CHAIR LASKEY: It's unanimous. Thank you.
Is there a third condition?
DR.
SOMBERG: I have a question. You said that we asked for the
hospitalization but was that placed -- that was in our questions. The hospitalization data in terms of the end
deaths hospitalization, et cetera, should that be a condition as well or is
that going to be included, Warren?
ACTING
CHAIR LASKEY: Well, the information
surrounding the implantation is to be included in the label -- in the IFU. This is a separate statement that we are
assigning to the vote as a condition of approval, so we'd like to see this
placed somewhere, but it's not going to have the same position that the other
information would have. That has its
own table, its box.
Third
condition?
DR.
WALDO: Warren, can I just make a
general point at this moment? I think
there's another big implication we haven't said. I'm not sure that this should stand on its own merits, but this
is really stealing a march on the SCDHeFT implications and I think that's a
very important part of how we think about this, too. I think someone just ought to say that.
ACTING
CHAIR LASKEY: You know, we want to
consider just the data that we have at hand in our panel pack today. We need to make a decision based on these
data, Dr. Waldo.
DR.
WALDO: No, I appreciate that fully and
that's why I said that first, but I mean, the implications are clear and they
should be understood by us. In effect,
that will happen but this clearly should stand on its own merits. There's no question about it. I just wanted to emphasize the real
implications for this.
ACTING
CHAIR LASKEY: Understood. If there are no other motions for additional
conditions, we are going to vote. Are
there any other motions for conditions?
No? So I'd like to restate the
motion and the conditions and then ask for a vote. The motion on the table is to approve the PMA with the following
conditions. Number one, that we approve
under the condition -- the first condition that the IFU be amended to remove
the language referring to the "all-cause" hospitalization and simply
refer to the benefit regarding "all-cause" mortality and improvement
in symptoms. The second condition
applied to the motion being that there is a separate statement regarding the
hospitalization information along with the appropriate explanatory language and
the caveats to be applied to that data.
So,
will all those voting members in favor of approval with these conditions raise
their hand? One, two, three, four,
five, six, seven --
DR.
WALDO: Aye.
ACTING
CHAIR LASKEY: -- eight, thank you. Unanimously approved. So eight to zero for the motion to approve. We need to just simply go around the table
and state your reasons for why you voted as you did. Dr. Kato?
DR.
KATO: Well, I think the -- I think
again, the hospitalization issue was debatable. Many of the areas, I think, were ill-defined. I think that the target of showing the CRT-D
can reduce mortality and reduce heart failure symptoms is a very powerful
statement and I think that's what patients are going to be looking for, so
that's why I voted the way I did.
DR.
YANCY: I voted in favor with
reluctance, because I'm concerned that we have -- this is strong language, but
I think we've bastardized a clinical trial because this was not a trial where
the primary end point was mortality alone; yet our label is suggesting
such. And I think that that is
academically inconsistent and something about which we should have some
angst. I think we also have a question
of clinical relevance here because the hospitalization burden is substantial
and as we said earlier, hospitalizations in this context are not all
equal. Those hospitalizations that
carry the greatest merit are, in fact, substantially impacted by this
methodology.
But
nevertheless, I applaud the panel for making a vote to bring more patients to
this platform in hopes that it will change outcomes and improve heart failure
overall.
DR.
MAISEL: I think the sponsor should be
commended for conducting an extremely important trial for bringing these
devices to a sick population in need of both mortality and symptomatic
improvement and I'm glad that we were able to do that today.
DR.
BRINKER: I echo those thoughts. I have no angst about the way we handled
this. I think that I would have much
more problem if I -- approving the original language given the uncertainties of
the definitions. I think they can be
worked out. I think that the paper that
was published and the reality of the practice habits of many physicians have
already established but I think that the imprint of the panel should be based
on what they feel is unequivocal scientifically justifiable and I didn't find
that for hospitalization end point in the study.
DR.
NORMAND: I also would have no
angst. I approved it with the
conditions for the reasons that were echoed by my colleague to my right. I do feel that the definition of
"all-cause" hospitalization means something to someone like me who
could be a patient and when someone says "all-cause" hospitalization
that actually means something in terms of how it is typically defined from the
patient's viewpoint. And I believe that
the way it was defined and measured in this study did not reflect what patients
are going to think it is and hence, that's the reason I voted with the
condition.
DR.
KRUCOFF: I voted the way I did for very similar reasons. I think ultimately the hospitalization issue
remains unresolvably ambiguous based on what's available today while the
reduction of heart failure symptoms and mortality does not. Again, I personally, probably would have
preferred the label to be slightly different but I think in the spirit of the
panel, the most important thing in my opinion was to bring this device
forward. This has been a huge effort
by a lot of very dedicated people in a very sick population and in a terrain
that's moving and changing and that we ended up with some ambiguities. In a key point like hospitalizations is part
of the real world of doing clinical trials but I think it's been a very thoughtful
day and I think at the end of the day, the important thing is to bring the
device forward and then let doctors and the practice of medicine kind of take
it from there.
DR.
SOMBERG: I voted for the motion because
I thought this was a very important study.
I think the mortality end point was important and I think there was
still some problems with the "all-cause" hospitalizations and that
this is a balanced motion taking all those considerations into account, not
penalizing the sponsor, but most importantly advocating its use for the
indicated patient population.
ACTING
CHAIR LASKEY: Ms. Moore, any additional
comments?
DR.
WALDO: This is Al Waldo, do I get -- I
think, you know, one of the few advantages of being at home is I could use the
dictionary to look up equipoise which was used so often. And I think we did this is a state of
equipoise which it means, as the Webster Dictionary said, the state of
equilibrium counterbalance. I think we
did this with balance and care. I think
it was a very important day. I think we
also have to remember that perfect is the enemy of good. I think this was a good study. It was far from perfect and I think we went
over pretty carefully the imperfections and I think our final recommendations
with the help of the panel put together some very good recommendations and I
thing we had a fruitful day and I'm glad I was a part of it.
ACTING
CHAIR LASKEY: Al, thank you very
much. And for my part, I hope never to
hear the term "equipoise" again.
This concludes the report and recommendations of the panel on PMA,
P010012, Supplement 26 from Guidant, and I too, add my gratitude and thanks for
excellent presentations from the sponsor and the agency. Thank you, thank you, all. Thank you, colleagues.
(Whereupon,
at 5:24 p.m. the above entitled matter concluded.)