title: Does Publication Bias Inflate the Apparent Efficacy of Psychological Treatment for Major Depressive Disorder? A Systematic Review and Meta-Analysis of US National Institutes of Health-Funded Trials.
abstract: BACKGROUND
  The efficacy of antidepressant medication has been shown empirically to be overestimated due to publication bias, but this has only been inferred statistically with regard to psychological treatment for depression. We assessed directly the extent of study publication bias in trials examining the efficacy of psychological treatment for depression.
  
  
  RESULTS
  We identified US National Institutes of Health grants awarded to fund randomized clinical trials comparing psychological treatment to control conditions or other treatments in patients diagnosed with major depressive disorder for the period 1972-2008, and we determined whether those grants led to publications. For studies that were not published, data were requested from investigators and included in the meta-analyses. Thirteen (23.6%) of the 55 funded grants that began trials did not result in publications, and two others never started. Among comparisons to control conditions, adding unpublished studies (Hedges' g = 0.20; CI95% -0.11~0.51; k = 6) to published studies (g = 0.52; 0.37~0.68; k = 20) reduced the psychotherapy effect size point estimate (g = 0.39; 0.08~0.70) by 25%. Moreover, these findings may overestimate the "true" effect of psychological treatment for depression as outcome reporting bias could not be examined quantitatively.
  
  
  CONCLUSIONS
  The efficacy of psychological interventions for depression has been overestimated in the published literature, just as it has been for pharmacotherapy. Both are efficacious but not to the extent that the published literature would suggest. Funding agencies and journals should archive both original protocols and raw data from treatment trials to allow the detection and correction of outcome reporting bias. Clinicians, guidelines developers, and decision makers should be aware that the published literature overestimates the effects of the predominant treatments for depression.
authors.affiliation: Department of Clinical, Neuro and Developmental Psychology, Faculty of Behavioural and Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands; EMGO Institute for Health and Care Research, VU University and VU University Medical Center Amsterdam, Amsterdam, The Netherlands.
authors.forename: Ellen
authors.initials: E
authors.lastname: Driessen
authors.affiliation: Department of Psychology, Vanderbilt University, Nashville, Tennessee, United States of America.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Hollon
authors.affiliation: Department of Clinical Psychology, University of Groningen, Groningen, The Netherlands; Department of Clinical and Health Psychology, Utrecht University, Utrecht, The Netherlands.
authors.forename: Claudi L H
authors.initials: CL
authors.lastname: Bockting
authors.affiliation: Department of Clinical, Neuro and Developmental Psychology, Faculty of Behavioural and Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands; EMGO Institute for Health and Care Research, VU University and VU University Medical Center Amsterdam, Amsterdam, The Netherlands.
authors.forename: Pim
authors.initials: P
authors.lastname: Cuijpers
authors.affiliation: Behavioral Health and Neurosciences Division, VA Portland Health Care System, Portland, Oregon, United States of America; Departments of Psychiatry and Pharmacology, Oregon Health & Science University, Portland, Oregon, United States of America.
authors.forename: Erick H
authors.initials: EH
authors.lastname: Turner
mesh_terms: D000928:Antidepressive Agents / Q000627:therapeutic use; D002986:Clinical Trials as Topic / Q000191:economics / Q000706:statistics & numerical data; D003865:Major Depressive Disorder / Q000453:epidemiology / Q000628:therapy*; D005380:Financing, Government / Q000706:statistics & numerical data; D006801:Humans; D009316:National Institutes of Health (U.S.); D011613:Psychotherapy / Q000191:economics / Q000379:methods; D017594:Publication Bias; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology
chemical_list: D000928:Antidepressive Agents