A meta-analysis 1 included randomized placebo-controlled trials of antidepressants; data from 6 studies including 718 patients were included. Three studies used paroxetine and 3 studies used imipramine. All studies had a follow-up of at least 6 weeks. Hamilton Depression Rating Scale (HDRS) was used in all studies. Individual patient-level data were obtained. Among patients with HDRS less than 23, Cohen d effect sizes for the difference between the medication and placebo were estimated to be less than 0.20, so there was no treatment effect. Estimates of the magnitude of the superiority of medication over placebo increased with increases in baseline depression severity and surpasses the threshold defined to a clinical significant difference with baseline HDRS score of 25.
Comment: The quality of evidence is downgraded by indirectness (differences in studied patients; patients with very low HDRS were excluded in trials).
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