A Meta-Analysis of Fluoxetine Outcome in the Treatment of Depression

A meta-analysis was conducted on all the double-blind, placebo-controlled efficacy trials of the antidepressant fluoxetine (Prozac). This drug has become the antidepressant most frequently prescribed by psychiatrists and has been hailed by the media as a "wonder drug." Results produced a relatively modest overall effect size that was no greater than effect sizes obtained by previous meta-analyses of tricyclic antidepressants. This study also examined the possibility that bias may have contaminated study outcome ratings. Because past studies suggest that the greater frequency of side effects in active drug groups unblinds study participants, we examined the relationship between study effect sizes and the percentage of patients reporting side effects. As predicted, both clinician and patient outcome ratings correlated significantly with the percentage of patients experiencing side effects. Questions are raised about the role of side effects in mediating drug outcome results.