Hiding negative trials by pooling them: a secondary analysis of pooled-trials publication bias in FDA-registered antidepressant trials.

Compared with positive trials, negative trials of antidepressants for depression were much more likely to be reported exclusively in pooled-trials publications. Pooled-trials publications flood the evidence base with often-redundant articles that, instead of addressing the original primary research question, present (positive) results on secondary questions. Therefore, pooled-trials publications distort the apparent risk-benefit profile of antidepressants.