To the Editor Dr Downing and colleagues analyzed the frequency of postmarket safety events among 222 novel therapeutics approved by the US Food and Drug Administration (FDA) between 2001 and 2010 and found that 32% had a postmarket safety event during a median 11.7 years after approval. The authors prespecified 7 features to assess for differences in events over time: (1) class, (2) therapeutic area, (3) priority review, (4) accelerated approval, (5) orphan product, (6) near–regulatory deadline approval, and (7) total review time. However, we would like to raise additional features that need further consideration to interpret the study results.