Recent years have seen a near-doubling of the number of studies examining the effects of psychotherapies for generalized anxiety disorder (GAD) in adults. The present article integrates this new evidence with the older literature through a quantitative meta-analysis. A total of 41 studies (with 2132 patients meeting diagnostic criteria for GAD) were identified through systematic searches in bibliographical databases, and were included in the meta-analysis. Most studies examined the effects of cognitive behavior therapy (CBT). The majority of studies used waiting lists as control condition. The pooled effect of the 38 comparisons (from 28 studies) of psychotherapy versus a control group was large (g=0.84; 95% CI: 0.71-0.97) with low to moderate heterogeneity. The effects based on self-report measures were somewhat lower than those based on clinician-rated instruments. The effects on depression were also large (g=0.71; 95% CI: 0.59-0.82). There were some indications for publication bias. The number of studies comparing CBT with other psychotherapies (e.g., applied relaxation) or pharmacotherapy was too small to draw conclusions about comparative effectiveness or the long-term effects. There were some indications that CBT was also effective at follow-up and that CBT was more effective than applied relaxation in the longer term.
Keywords: Cognitive behavior therapy; Comparative outcome studies; Generalized anxiety disorder; Meta-analysis; Psychotherapy; Randomized trial.
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