title: The effects of blinding on the outcomes of psychotherapy and pharmacotherapy for adult depression: A meta-analysis.
abstract: BACKGROUND
  Randomized trials with antidepressants are often run under double blind placebo-controlled conditions, whereas those with psychotherapies are mostly unblinded. This can introduce bias in favor of psychotherapy when the treatments are directly compared. In this meta-analysis, we examine this potential source of bias.
  
  
  METHODS
  We searched Pubmed, PsycInfo, Embase and the Cochrane database (1966 to January 2014) by combining terms indicative of psychological treatment and depression, and limited to randomized trials. We included 35 trials (with 3721 patients) in which psychotherapy and pharmacotherapy for adult depression were directly compared with each other. We calculated effect sizes for each study indicating the difference between psychotherapy and pharmacotherapy at post-test. Then, we examined the difference between studies with a placebo condition and those without in moderator analyses.
  
  
  RESULTS
  We did not find a significant difference between the studies with and those without a placebo condition. The studies in which a placebo condition was included indicated no significant difference between psychotherapy and pharmacotherapy (g=-0.07; NNT=25). Studies in which no placebo condition was included (and patients and clinicians in both conditions were not blinded), resulted in a small, but significant difference between psychotherapy and pharmacotherapy in favor of pharmacotherapy (g=-0.13; NNT=14).
  
  
  CONCLUSIONS
  Studies comparing psychotherapy and pharmacotherapy in which both groups of patients (and therapists) are not blinded (no placebo condition is included) result in a very small, but significantly higher effect for pharmacotherapy.
authors.affiliation: Department of clinical psychology, VU University Amsterdam, 1, Van der Boechorststraat, 1081 BT Amsterdam, The Netherlands; EMGO Institute for Health and Care Research, The Netherlands. Electronic address: p.cuijpers@vu.nl.
authors.forename: P
authors.initials: P
authors.lastname: Cuijpers
authors.affiliation: Department of clinical psychology, VU University Amsterdam, 1, Van der Boechorststraat, 1081 BT Amsterdam, The Netherlands; EMGO Institute for Health and Care Research, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Karyotaki
authors.affiliation: Department of behavioural sciences and learning, Swedish institute for disability research, Linköping University, Sweden; Department of clinical neuroscience, psychiatry section, Karolinska Institutet, Stockholm, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Andersson
authors.affiliation: Key laboratory of mental health, institute of psychology, Chinese academy of sciences, Beijing, China.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of psychiatry and psychotherapy, university of Leipzig, Leipzig, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Mergl
authors.affiliation: Department of psychiatry and psychotherapy, university of Leipzig, Leipzig, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Hegerl
mesh_terms: D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use*; D003863:Depression / Q000453:epidemiology / Q000628:therapy; D004311:Double-Blind Method; D006801:Humans; D015990:Placebo Effect; D011613:Psychotherapy / Q000379:methods*; D016032:Randomized Controlled Trials as Topic / Q000379:methods*
chemical_list: D000928:Antidepressive Agents
keywords: Cognitive-behavior therapy; Major depression; Meta-analysis; Pharmacotherapy; Psychotherapy