A meta-analysis of early sustained response rates between antidepressants and placebo for the treatment of major depressive disorder

Context: Pattern analysis suggests that "true" drug response is characterized by clinical improvement that is not subsequently followed by a worsening of symptoms (sustained clinical response). To date, several reports demonstrate that early response rates are equivalent between antidepressant-treated and placebo-treated groups of patients with major depressive disorder, suggesting that patients who demonstrate significant and sustained symptom improvement during the first 2 weeks of treatment are not responding to the antidepressant itself, but to nonspecific, placebo-like factors. Objective: To compare early sustained response rates between antidepressant- and placebo-treated adults with major depressive disorder. Data Sources: Medline/Pubmed were searched. No year of publication limits were used. Study Selection: Randomized, double-blind, placebo-controlled antidepressant trials or pooled reports/meta-analyses of such trials reporting early sustained response rates for major depressive disorder. The decision to include studies in the meta-analysis was performed by 2 reviewers. Data Extraction: Data were extracted with the use of a precoded form. Data Synthesis: Analyses were performed on the proportion of patients who achieved a sustained response the first 2 weeks of treatment, as well as the first week of treatment. A random-effects model with fixed drug effects was used to combine the studies and make comparisons of sustained early response rates between antidepressant- and placebo-treated groups. Data from 8 reports involving a total of 7121 major depressive disorder patients (4076 randomized to treatment with an antidepressant and 3045 randomized to placebo) were analyzed. Antidepressant-treated patients were more likely to demonstrate sustained clinical response by 2 weeks (odds ratio 2.06, 95% CI: 1.52-2.8) or 1 week of treatment (odds ratio 1.50, 95% CI: 1.08-2.08) than placebo-treated patients. Conclusions: The results of the present analysis suggest that "true" drug response can occur the first 2 week as well as the first week of treatment of major depressive disorder with conventional antidepressants.