Reviews of the relative efficacy of psychotherapy and combined therapy (psychotherapy with pharmacotherapy) for depression have yielded contradicting conclusions. This may be explained by the clinical heterogeneity of the studies reviewed.

To conduct a meta-analysis with an acceptable level of homogeneity in order to investigate the relative efficacy of psychotherapy and combined therapy in the acute treatment of depression.

A systematic search was performed for RCTs published between 1980 and 2005 comparing psychotherapy and combined therapy in adult psychiatric outpatients with non-psychotic unipolar major depressive disorder. The studies were classified according to the chronicity and severity of the depression. Data were pooled by means of meta-analysis and statistical tests were conducted to measure heterogeneity.

The meta-analysis included seven studies looking at a total of 903 patients. None of the heterogeneity tests established significance. This indicates a lack of evidence for the heterogeneity of the results. The dropout rates did not differ significantly between the two treatment modalities (25% in combined therapy and 24% in psychotherapy, p=0.77). At treatment termination, the intention-to-treat remission rate for combined therapy (46%) was better than for psychotherapy (34%) (p=0.0007); Relative Risk 1.32 (95% CI: 1.12-1.56), Odds Ratio 1.59 (95% CI: 1.22-2.09). In moderate depression, the difference between the remission rate for combined therapy and psychotherapy was statistically significant (47% compared to 34% respectively, p=0.001). This was not the case in mild major depression (42% compared to 37% respectively, p=0.29). The difference was also statistically significant in chronic major depression (48% compared to 32%, p<0.001), but not in non-chronic major depression (43% compared to 37%, p=0.22). On a more specific level, no differences were found in the remission rates for the treatment modalities in mild or moderate non-chronic depression. Combined therapy led to significantly better results than psychotherapy in moderate chronic depression only (48% compared to 32%, p<0.001).

In the acute treatment of adult psychiatric outpatients with major depressive disorder, patient compliance with combined therapy matches compliance with psychotherapy alone. Combined therapy is more efficacious than psychotherapy alone. However, these results depend on severity and chronicity. Combined therapy outperformed psychotherapy in moderate chronic depression only. No differences were found in mild and moderate non-chronic depression. No data were found for mild chronic depression and for severe depression.