Three hundred twenty-one NASs (74.4%) had a standard review, and 112 (25.6%) had a priority review. (The approval status of 1 product could not be determined.) For products with a standard review, there was a 19.8% (95% CI, 14.8-24.8) estimate of acquiring a serious safety issue compared with a 34.2% (95% CI, 24.3-44.2) estimate for an NAS with a priority review (P = .005, log-rank test). Eighty-one NASs with a priority review that were not major therapeutic advances were compared with the 321 NASs with a standard review. The estimate of this group of priority review NASs having a serious safety issue was 36.0% (95% CI, 24.3-47.7) compared with 19.8% (95% CI, 14.8-24.8) for standard review NASs (P = .004, log-rank test).