Problem-solving therapy (PST) is one of the best examined types of psychotherapy for adult depression. No recent meta-analysis has examined the effects of PST compared to control groups or to other treatments. We wanted to verify whether PST is effective, whether effects are comparable to those of other treatments, and whether we could identify the possible sources of high heterogeneity that was found in earlier meta-analyses.

We conducted systematic searches in bibliographical databases, including PubMed, PsycInfo, Embase and the Cochrane database of randomized trials.

We included 30 randomized controlled trials on PST (with 3530 patients), in which PST was compared to control conditions, with other therapies, and with pharmacotherapy. We could compare these 30 trials on PST also with 259 trials on other psychotherapies for adult depression. The effect size of PST versus control groups was g = 0.79 (0.57–1.01) with very high heterogeneity (I2 = 84; 95% CI: 77–88). The effect size from the 9 studies with low risk of bias was g = 0.34 (95% CI: 0.22–0.46) with low heterogeneity (I2 = 32; 95% CI: 0–68), which is comparable to the effects of other psychotherapies. PST was a little more effective than other therapies in direct comparisons, but that may be explained by the considerable number of studies with researcher allegiance towards PST. In meta-regression analyses of all controlled studies, no significant difference between PST and other therapies was found.

PST is probably an effective treatment for depression, with effect sizes that are small, but comparable to those found for other psychological treatments of depression.