Regency D
A Practical Approach to Achieving Person-Years Needed in Post-Marketing Long-Term Safety Studies (303939)
*Raghava Danwada, AbbVie
Huifang Liang, Abbvie
Dianlin Guo, Abbvie
Brian Waterhouse, Abbvie
Chen Chen, Abbvie
Keywords: PASS, PV, Safety Studies, SAS software
In planning post-authorization long-term drug safety studies (PASS), sample size is an important consideration. The minimum person-years of observation depends on incidence rate in the comparator group, incidence ratio of study drug to comparator, exposure ratio of study drug to comparator, significant level and power. However, how to plan for the number of patients enrolled per year is challenging. For example, a malignancy outcome may occur after many years and loss-to follow-up as well as market penetration can have profound impact on sample size estimate. We provide here an approach and a SAS program that we have used in designing a PASS study. This approach considers (1) annually accrued number of patients exposed to a study drug, (2) an annual attrition rate, (3) accrual time, (4) additional years of follow-up after the last patient is recruited. Using the program, we estimated varying cumulative patient-years for the study drug, total patients and mean follow-up years for exposed and comparator drug groups. We then use this information to inform our choices of the number of patients enrolled per year, tolerable attrition rate, and years of follow-up.