A regulatory Apologia--a review of placebo-controlled studies in regulatory submissions of new-generation antidepressants.

Data on percentage of patients experiencing a relevant response (>50% reduction of the baseline Hamilton Depression Scale (HAMD) score), average baseline severity and sample size were retrieved for all placebo-controlled studies in regulatory submissions of SSRIs and SNRIs between 1984 and 2003. Overall there was 16%-units (95% CI: 12; 20) more responders on active drug compared to placebo. There was no evidence of a diminishing magnitude of effect with lower severity at baseline. With one exception significant differences varying between 13.5 and 19.3%-units were demonstrated for the individual antidepressants. Statistically significant mean differences versus placebo in change in HAMD are not a proper basis for evaluation of clinical relevance and are not sufficient for approval. Differences in the percentage of patients experiencing a clinically relevant response should also be demonstrated. In this respect, the approved SSRIs and SNRIs were found superior to placebo, independent of severity of depression.