PURPOSE
Several factors limit the statistical power of drug safety surveillance during the early post-approval period, including uptake of the drug and lag in data availability. This study characterized new drug uptake in the Mini-Sentinel Distributed Database and determined statistical power to detect levels of risk in post-launch safety assessments.
METHODS
The cumulative exposure among initiators of 46 new molecular entities approved from 2008 to 2011 was assessed. Using a Poisson estimation method, minimum incidence rate ratios (IRRs) detectable, with 80% power, were calculated under varying background incidence rates.
RESULTS
Twelve products (26.1%) had more than 15 000 new users after 2 years. With comparator group incidence rate of 1/1000 person-years, 16 (33.3%) products had enough exposure to detect an IRR of 5 with 24 months of data collected that would be available for assessment at 33 months post-launch. With an incidence rate of 5/1000 person-years, 23 (50%) products had enough exposure to detect an IRR of ≥3 with 2 years of data collected. At 33 months post-launch, only two (4.3%) of the drugs examined had enough data availability to detect IRR of <2, and eight (17.4%) of <3, with a background rate of 1/1000 person-years.
CONCLUSION
This study highlights the importance of drug uptake and data availability in early post-approval drug safety surveillance in Mini-Sentinel. There is limited ability to detect rate ratios below three for events with background rates of 1/1000 person-years or lower. This is largely due to low product uptake. Copyright © 2016 John Wiley & Sons, Ltd.