PLACEBO RUN-IN PERIOD IN STUDIES OF DEPRESSIVE-DISORDERS - CLINICAL, HEURISTIC AND RESEARCH IMPLICATIONS

Background In spite of the virtually ubiquitous nature of the initial 10-day placebo run-in period (IPR) in drug trials, there is little emp irical data establishing its relevance. Method Data from 593 subjects were examined retrospectively to determine whether or not the prognosi s of subjects minimally improved during the IPR was different to those who were unimproved. The IPR period was single-blind and was followed by a six-week double-blind phase in all studies. Results Twenty-six p ercent of the subjects were minimally improved and 74% were unimproved . Approximately 10% of the subjects who were much improved were not fo llowed systematically Across a range of diagnosis, severity and chroni city subjects minimally improved (versus unimproved) after IPR had a m ore favourable prognosis whether assigned to drug or placebo. Conclusi ons Change during IPR appears to be a meaningful predictor. Stratifica tion should be considered in future antidepressant studies.