Larger effect sizes in nonrandomized studies are associated with higher rates of EMA licensing approval.

OBJECTIVES The aim of this study was to evaluate how often the European Medicines Agency (EMA) has authorized drugs based on nonrandomized studies and whether there is an association between treatment effects and EMA preference for further testing in randomized clinical trials (RCTs). STUDY DESIGN AND SETTING We reviewed all initial marketing authorizations in the EMA database on human medicines between 1995 and 2015 and included authorizations granted without randomized data. We extracted data on treatment effects and EMA preference for further testing in RCTs. RESULTS Of 723 drugs, 51 were authorized based on nonrandomized data. These 51 drugs were licensed for 71 indications. In the 51 drug-indication pairs with no preference for further RCT testing, effect estimates were large [odds ratio (OR): 12.0 (95% confidence interval {CI}: 8.1-17.9)] compared to effect estimates in the 20 drug-indication pairs for which future RCTs were preferred [OR: 4.3 (95% CI 2.8-6.6)], with a significant difference between effects (P = 0.0005). CONCLUSION Nonrandomized data were used for 7% of EMA drug approvals. Larger effect sizes were associated with greater likelihood of approval based on nonrandomized data alone. We did not find a clear treatment effect threshold for drug approval without RCT evidence.