From: A. David Paltiel []
Sent: Friday, February 17, 2006 12:34 PM
To: Jehn, Donald
Cc: Rochelle Walensky; A. David Paltiel
Subject: Blood Products Advisory Committee, March meeting

Dear Dr. Jehn,

We write to offer our thoughts and services with regard to the upcoming Blood Products Advisory Committee meeting (scheduled for March 9-10, 2006) and the discussion of studies to support the approval of OTC home HIV testing kits. As the authors of several recent papers* on the clinical and economic impact of expanded HIV testing, we may be able to speak with some authority on questions of value for money and the performance of HIV testing in a variety of settings. 

We have read both the transcript of the November, 2005 meeting of the Board and the online briefing materials for the upcoming meeting.  We are concerned that there is still confusion with regard to the estimation and interpretation of test attributes (e.g., sensitivity, specificity, predictive values) and how the inherent accuracy of a diagnostic system interacts with attributes of the target population (e.g., incidence, prevalence, seroconversion rates) in which it is used.  We are concerned that this confusion has worked its way into the proposed studies scheduled to be discussed at the March meeting.

We are also concerned that there is nothing in the proposed studies that will shed light on the critical question of target markets and the price sensitivity of demand for home testing.  As noted by several Board members in November, there is reason to worry that home HIV testing will attract a predominantly affluent clientele, composed disproportionately of HIV-uninfected, “worried well” persons and very recently infected, undetectable cases.  Quite independent of the inherent sensitivity and specificity of the test kit itself, this “selection bias” will have the perverse effect of simultaneously increasing both the proportion of false-positive results and the proportion of false-negative results, while making little appreciable dent in the size of the undetected HIV pool. What needs to be studied further is the degree to which retail pricing will influence demand among the vulnerable populations in greatest need of a more convenient, more accessible HIV test.

We would be very happy to submit testimony on these concerns– either in person or in writing – if you think this could be of some assistance.


A. David Paltiel, MBA, PhD                                         Rochelle P. Walensky, MD, MPH
Yale School of Medicine                                               Harvard Medical School
Yale School
of Management                                         Massachusetts General Hospital

* Paltiel AD, Weinstein MC, Kimmel AD, Seage GR, Losina E, Zhang H, Freedberg KA, and Walensky RP.  Expanded HIV Screening in the United States – An Analysis of Cost-effectiveness.
New England
Journal of Medicine (2005) 352:586-595.

    Walensky RP, MC Weinstein, HE Smith, KA Freedberg, AD Paltiel.  Optimal Allocation of Testing Dollars: The Example of HIV Counseling, Testing, and Referral.
Medical Decision Making
(2005) 25:321-329.

    Walensky RP, Weinstein MC, Kimmel AD, Seage GR, Losina E, Sax PE, Zhang H, Smith HE, Freedberg KA, and Paltiel AD. Routine HIV Testing: An Economic Evaluation of Current Guidelines.
American Journal of Medicine
(2005) 118:292-300.

    Resch S, Altice FL, and Paltiel AD.  Cost-effectiveness of HIV screening for incarcerated pregnant women. 
Journal of Acquired Immune Deficiency Syndromes (2005) 38:163–173.

    Walensky RP, Losina E, Malatesta L, Barton GE, O’Connor CA, Skolnik PR, Hall JM, McGuire JF, and Freedberg KA.  The High Yield of Routine HIV Screening in Urgent Care Sites in Massachusetts
American Journal of Public Health
2005 Jan;95(1):71-3.

    Walensky RP, Freedberg KA, Losina E, Skolnik PR, Hall JM, Malatesta L, Barton GE, O’Connor CA, McGuire JF.  Voluntary HIV Testing as Part of Routine Medical Care — Massachusetts, 2002.
Morbidity & Mortality Weekly Report 2004; 53:523-526.


A. David Paltiel, PhD
Associate Professor
Yale School of Medicine
60 College Street, Room 305
New Haven, CT 06520-8034
(For FedEx, please use zip code 06510)

voice: 203-785-2862
fax: 203-785-6287
skype: david_paltiel