Background: The current study presents the results of a meta-analysis of 39 randomized controlled trials on the efficacy of acceptance and commitment therapy (ACT), including 1,821 patients with mental disorders or somatic health problems. Methods: We searched PsycINFO, MEDLINE and the Cochrane Central Register of Controlled Trials. Information provided by the ACBS (Association of Contextual Behavioral Science) community was also included. Statistical calculations were conducted using Comprehensive Meta-Analysis software. Study quality was rated using a methodology rating form. Results: ACT outperformed control conditions (Hedges' g = 0.57) at posttreatment and follow-up assessments in completer and intent-to-treat analyses for primary outcomes. ACT was superior to waitlist (Hedges' g = 0.82), to psychological placebo (Hedges' g = 0.51) and to treatment as usual (TAU) (we defined TAU as the standard treatment as usual; Hedges' g = 0.64). ACT was also superior on secondary outcomes (Hedges' g = 0.30), life satisfaction/quality measures (Hedges' g = 0.37) and process measures (Hedges' g = 0. 56) compared to control conditions. The comparison between ACT and established treatments (cognitive behavioral therapy) did not reveal any significant differences between these treatments (p = 0.140). Conclusions: Our findings indicate that ACT is more effective than treatment as usual or placebo and that ACT may be as effective in treating anxiety disorders, depression, addiction, and somatic health problems as established psychological interventions. More research that focuses on quality of life and processes of change is needed to understand the added value of ACT and its transdiagnostic nature.

Hayes SC, Strosahl KD, Wilson KG: Acceptance and Commitment Therapy: The Process and Practice of Mindful Change, ed 2. New York, Guilford Press, 2012.
Öst LG: Efficacy of the third wave of behavioral therapies: a systematic review and meta-analysis. Behav Res Ther 2008;46:296-321.
Powers MB, Zum Vörde Sive Vörding MB, Emmelkamp PMG: Acceptance and commitment therapy: a meta-analytic review. Psychother Psychosom 2009;78:73-80.
Ruiz F: Acceptance and commitment therapy versus traditional cognitive behavioral therapy: a systematic review and meta-analysis of current empirical evidence. Int J Psychol Psychol Ther 2012;12:333-357.
Gifford EV, Kohlenberg BS, Hayes SC, Antonuccio DO, Piasecki MM, Rasmussen-Hall ML, Palm KM: Acceptance-based treatment for smoking cessation. Behav Ther 2004;35:689-705.
Gifford EV, Kohlenberg BS, Hayes SC, Pierson HM, Piasecki MP, Antonuccio DO, Palm KM: Does acceptance and relationship focused behavior therapy contribute to bupropion outcomes? A randomized controlled trial of functional analytic psychotherapy and acceptance and commitment therapy for smoking cessation. Behav Ther 2011;42:700-715.
Hayes S, Wilson K, Gifford E, Bissett R, Piasecki M, Batten S, Byrd M, Gregg J: A preliminary trial of twelve-step facilitation and acceptance and commitment therapy with polysubstance-abusing methadone-maintained opiate addicts. Behav Ther 2004;35:667-688.
Westin VZ, Schulin M, Hesser H, Karlsson M, Noe RZ, Olofsson U, Stalby M, Wisung G, Andersson G: Acceptance and commitment therapy versus tinnitus retraining therapy in the treatment of tinnitus: a randomised controlled trial. Behav Res Ther 2011;49:737-747.
Hayes L, Boyd CP, Sewell J: Acceptance and commitment therapy for the treatment of adolescent depression: a pilot study in a psychiatric outpatient setting. Mindfulness 2011;2:86-94.
Rost AD, Wilson K, Buchanan E, Hildebrandt MJ, Mutch D: Improving psychological adjustment among late-stage ovarian cancer patients: examining the role of avoidance in treatment. Cogn Behav Pract 2012;19:508-517.
Borenstein M, Rothstein H, Cohen J: Comprehensive Meta-Analysis: A Computer Program for Research Synthesis. Englewood, Biostat, 1999.
Hunter J, Schmidt F: Methods of Meta-Analysis: Correcting Error and Bias in Research Findings. Thousand Oaks, Sage, 2004.
Tabachnik B, Fidell L: Using Multivariate Statistics, ed 6. Boston, Allyn and Bacon, 2013.
Cuijpers P, van Straten A, Bohlmeijer E, Hollon S, Andersson G: The effects of psychotherapy for adult depression are overestimated: a meta-analysis of study quality and effect size. Psychol Med 2010;40:211-223.
Smout MF, Hayes L, Atkins PWB, Klausen J, Duguid JE: The empirically supported status of acceptance and commitment therapy: an update. Clin Psychol 2012;16:97-109.
Hofmann S, Smits J: Pitfalls of meta-analyses. J Nerv Ment Dis 2008;196:716-717.
Smits J, Hofmann S: A meta-analytic review of the effects of psychotherapy control conditions for anxiety disorders. Psychol Med 2009;39:229-239.
Society of Clinical Psychology 2013, retrieved December 12, 2013.
Levin ME, Hildebrandt MJ, Lillis J, Hayes SC: The impact of treatment components suggested by the psychological flexibility model: a meta-analysis of laboratory-based component studies. Behav Ther 2012;43:741-756.
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