Reporting of a Standardized Incidence Rate for Recurrent Adverse Events

• Activity Number: 103
• Type: Topic Contributed
• Date/Time: Monday, August 3, 2009 : 8:30 AM to 10:20 AM
• Sponsor: Biopharmaceutical Section
• Author(s): John C. Evans*+ and Wen Ding and Jian Huang and Vivek Pradhan
• Companies: Boston Scientific Corporation and Boston Scientific Corporation and Boston Scientific Corporation and Boston Scientific Corporation
• Keywords: Standardized AE incidence rate per 100 patient-years ; Negative Binomial ; Recurrent adverse events

Abstract

FDA has requested that we report the standardized event-based AE incidence rate per 100 patient-years, instead of the more usual patient-based rate. When AEs recur on a subject, the methods for calculating the standardized rate and its variance are well known. However, they assume that the events recur randomly over time, so that the number of events per subject follows a Poisson distribution, wherein the variance equals the mean. For events not randomly distributed over time, due to their dependence on the previous number and times of events, we assume that the number of events per subject follows a Negative Binomial distribution, wherein the variance exceeds the mean. Thus, although the incidence rate is the same, the calculation of the variance is more complicated. We report the standardized incidence rate of recurrent events for a single device study and for comparing two devices.