Cognitive behavioral treatments of obsessive–compulsive disorder. A systematic review and meta-analysis of studies published 1993–2014 Lars-Göran Öst a,b,c,d, ⁎, Audun Havnen c,d , Bjarne Hansen c,d , Gerd Kvale c,d a Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden b Department of Psychology, Stockholm University, Sweden c Department of Clinical Psychology, University of Bergen, Norway d Haukeland University Hospital, OCD-team, 5021 Bergen, Norway HIGHLIGHTS • CBT yielded very large effect sizes compared to wait list and placebo. • CBT was significantly better than antidepressants. • The addition of antidepressants did not potentiate the effect of CBT. • There was no significant difference between ERP and cognitive therapy. • There was no significant difference between individual and group treatment. abstract article info Article history: Received 14 January 2015 Received in revised form 14 May 2015 Accepted 11 June 2015 Available online 14 June 2015 Keywords: Obsessive–compulsive disorder Exposure and response prevention Cognitive therapy Meta-analysis Systematic review Obsessive–compulsive disorder is ranked by the WHO as among the 10 most debilitating disorders and tends to be chronic without adequate treatment. The only psychological treatment that has been found effective is cogni- tive behavior therapy (CBT). This meta-analysis includes all RCTs (N = 37) of CBT for OCD using the interview- based Yale–Brown Obsessive Compulsive Scale, published 1993 to 2014. The effect sizes for comparisons of CBT with waiting-list (1.31), and placebo conditions (1.33) were very large, whereas those for comparisons between individual and group treatment (0.17), and exposure and response prevention vs. cognitive therapy (0.07) were small and non–significant. CBT was significantly better than antidepressant medication (0.55), but the combina- tion of CBT and medication was not significantly better than CBT plus placebo (0.25). The RCTs have a number of methodological problems and recommendations for improving the methodological rigor are discussed as well as clinical implications of the findings. © 2015 Elsevier Ltd. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 2. Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 2.1. Literature search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 2.1.1. Inclusion criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 2.2. Categorization of background variables and potential moderators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 2.2.1. Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 2.2.2. Declining participation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 2.2.3. Attrition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 2.2.4. Type of exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 2.2.5. Mode of application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 2.2.6. Format and amount of therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 2.2.7. Statistical analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 2.2.8. Reliability of categorizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Clinical Psychology Review 40 (2015) 156–169 ⁎ Corresponding author at: Department of Clinical Neuroscience, Section of Psychology, Karolinska Institutet, S-171 77 Stockholm, Sweden. E-mail address: ost@psychology.su.se (L.-G. Öst). http://dx.doi.org/10.1016/j.cpr.2015.06.003 0272-7358/© 2015 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Clinical Psychology Review