Side effects and the "blindability" of clinical drug trials.

A novel, simple approach to retrospective assessment of "blindability" was applied to data on outpatients in a controlled, double-blind clinical comparison of a putative antidepressant, etoperidone, and placebo. A "blind" evaluator proved capable of discriminating between the active drug and placebo on the basis of reported side effects alone, raising questions about the true blindness of the study.