How effective are cognitive behavior therapies for major depression and anxiety disorders? A meta-analytic update of the evidence.

We report the current best estimate of the effects of cognitive behavior therapy (CBT) in the treatment of major depression (MDD), generalized anxiety disorder (GAD), panic disorder (PAD) and social anxiety disorder (SAD), taking into account publication bias, the quality of trials, and the influence of waiting list control groups on the outcomes. In our meta-analyses, we included randomized trials comparing CBT with a control condition (waiting list, care-as-usual or pill placebo) in the acute treatment of MDD, GAD, PAD or SAD, diagnosed on the basis of a structured interview. We found that the overall effects in the 144 included trials (184 comparisons) for all four disorders were large, ranging from g=0.75 for MDD to g=0.80 for GAD, g=0.81 for PAD, and g=0.88 for SAD. Publication bias mostly affected the outcomes of CBT in GAD (adjusted g=0.59) and MDD (adjusted g=0.65), but not those in PAD and SAD. Only 17.4% of the included trials were considered to be high-quality, and this mostly affected the outcomes for PAD (g=0.61) and SAD (g=0.76). More than 80% of trials in anxiety disorders used waiting list control groups, and the few studies using other control groups pointed at much smaller effect sizes for CBT. We conclude that CBT is probably effective in the treatment of MDD, GAD, PAD and SAD; that the effects are large when the control condition is waiting list, but small to moderate when it is care-as-usual or pill placebo; and that, because of the small number of high-quality trials, these effects are still uncertain and should be considered with caution.