As described in the Approach and Results section, a potential alternative model was developed by modifying the calculations pertaining to the average time weighting factors used to produce the adjustments for changes in review activities for the PDUFA IV Workload Adjuster. As part of the development of this potential alternative model, we suggest that the calculation of the average time weighting factors for each review activity component include an additional weighting scheme. This weighting scheme might assist in more accurately capturing the effort expended on each review activity on a relative year-to-year basis. Using the currently available data, the weighting scheme for time weighting factors will utilize CDER and CBER process costs for NDAs/BLAs and INDs for each fiscal year. The specific calculations associated with the weighting scheme for the alternative methodology are included in Appendix D.
Since the alternative model yields only a 0.02% increase in the final PDUFA IV Workload Adjuster value, this may not warrant a change in the current Workload Adjuster. However, we also believe that including this additional weighting factor in the future might provide a methodology to measure workload changes more completely in both absolute and relative terms, and suggest that FDA consider the alternative model in the future as more data become available to test it.
In addition, based on our data validation efforts described in the Data Collection and Validation section, we recommend that the FDA should consider implementing additional quality control procedures and maintaining documentation on the data obtained for the adjustment for changes in review activities for the PDUFA IV Workload Adjuster. We have been informally advised by the FDA that such steps are being taken.