A meta-analysis of nonrandomized effectiveness studies on outpatient cognitive behavioral therapy for adult anxiety disorders

Abstract Objective The primary aim of this study was to assess the overall effectiveness of individual and group outpatient cognitive behavioral therapy (CBT) for adults with a primary anxiety disorder in routine clinical practice. Method We conducted a random effects meta-analysis of 71 nonrandomized effectiveness studies on outpatient individual and group CBT for adult anxiety disorders. Standardized mean gain effect sizes pre- to posttreatment, and posttreatment to follow-up are reported for disorder-specific symptoms, depression, and general anxiety. The mean dropout from CBT is reported. Results Outpatient CBT was effective in reducing disorder-specific symptoms in completer ( d  = 0.9…