Reply to: “Comment on ‘Review of patient registries in dermatology’”

To the Editor: We thank Zweegers et al for suggesting additional helpful, important registries. The psoriasis registries they described provide important complements to randomized control trial (RCT) data. Registries provide information about real-world effectiveness, about how well drugs work over the course of long-term, chronic diseases, and perhaps most importantly, about drug safety, as clinical trials tend not to be large enough or long enough to fully elucidate rare risks. A limitation of patient registries is that patients are generally not randomized to different treatment groups, making it essential to address potential biases in treatment assignment when making comparisons between different treatment groups.

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