title: Cognitive-behavioural therapy for the symptoms of schizophrenia: systematic review and meta-analysis with examination of potential bias.
abstract: BACKGROUND
  Cognitive-behavioural therapy (CBT) is considered to be effective for the symptoms of schizophrenia. However, this view is based mainly on meta-analysis, whose findings can be influenced by failure to consider sources of bias.
  
  
  OBJECTIVE
  To conduct a systematic review and meta-analysis of the effectiveness of CBT for schizophrenic symptoms that includes an examination of potential sources of bias.
  
  
  METHODS
  Data were pooled from randomised trials providing end-of-study data on overall, positive and negative symptoms. The moderating effects of randomisation, masking of outcome assessments, incompleteness of outcome data and use of a control intervention were examined. Publication bias was also investigated.
  
  
  RESULTS
  Pooled effect sizes were -0.33 (95% CI -0.47 to -0.19) in 34 studies of overall symptoms, -0.25 (95% CI -0.37 to -0.13) in 33 studies of positive symptoms and -0.13 (95% CI -0.25 to -0.01) in 34 studies of negative symptoms. Masking significantly moderated effect size in the meta-analyses of overall symptoms (effect sizes -0.62 (95% CI -0.88 to -0.35) v. -0.15 (95% CI -0.27 to -0.03), P = 0.001) and positive symptoms (effect sizes -0.57 (95% CI -0.76 to -0.39) v. -0.08 (95% CI -0.18 to 0.03), P<0.001). Use of a control intervention did not moderate effect size in any of the analyses. There was no consistent evidence of publication bias across different analyses.
  
  
  CONCLUSIONS
  Cognitive-behavioural therapy has a therapeutic effect on schizophrenic symptoms in the 'small' range. This reduces further when sources of bias, particularly masking, are controlled for.
authors.affiliation: S. Jauhar, MB, ChB, BSc(Hons), MRCPsych, Department of Psychosis Studies, Institute of Psychiatry, London, UK; P. J. McKenna, MB, ChB, MRCPsych, J. Radua, MD, PhD, FIDMAG Germanes Hospitalàries Research Foundation, Barcelona and CIBERSAM, Spain; E. Fung, MD, Department of Psychiatry, Faculty of Medicine, University of Calgary, Alberta, Canada; R. Salvador, PhD, FIDMAG Germanes Hospitalàries Research Foundation, Barcelona and CIBERSAM, Spain; K. R. Laws, PhD, School of Life and Medical Sciences, University of Hertfordshire, Hatfield, UK.
authors.forename: S
authors.initials: S
authors.lastname: Jauhar
authors.forename: P J
authors.initials: PJ
authors.lastname: McKenna
authors.forename: J
authors.initials: J
authors.lastname: Radua
authors.forename: E
authors.initials: E
authors.lastname: Fung
authors.forename: R
authors.initials: R
authors.lastname: Salvador
authors.forename: K R
authors.initials: KR
authors.lastname: Laws
mesh_terms: D015982:Bias; D015928:Cognitive Behavioral Therapy; D006801:Humans; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D011569:Psychiatric Status Rating Scales; D017594:Publication Bias / Q000706:statistics & numerical data*; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D012559:Schizophrenia / Q000628:therapy*; D012565:Schizophrenic Psychology