CRD summary

This review concluded that cognitive behavioural therapy reduced relapse and improved symptoms in major depression, but was not effective for schizophrenia or bipolar disorder. Limitations in the review, particularly a lack of formal validity assessment, suggest that the conclusions should be treated with caution.

Authors' objectives

To assess the effectiveness of cognitive-behavioural therapy (CBT) for serious mental illness based on trials that attempted to guard against important sources of bias.

Searching

Existing comprehensive meta-analyses for schizophrenia, depression and bipolar disorder were used as sources of studies. MEDLINE, EMBASE and PsycINFO were searched from five years before publication of the first meta-analysis (1998) to January 2009. Review articles, reference lists of obtained papers and trials registers were checked. Only published studies were included. There were no restrictions on language or publication date.

Study selection

Eligible studies examined the effectiveness of CBT in adults who met any diagnostic criteria for schizophrenia, major depression or bipolar disorder. A definition of CBT was provided in the paper. Outcomes of interest were symptoms and relapse. Studies of effects of CBT on symptoms were required to use a control intervention that the study investigators considered not to have specific therapeutic effects or that might be reasonably thought to have no such effects. Studies that compared CBT with a pill placebo were eligible. Studies of relapse prevention that used treatment as usual as a control were included. Small studies (<10 participants in either group) and pilot studies were excluded. Studies did not have to use blinded evaluation. It was unclear whether studies had to be randomised.

Included studies used a range of control interventions, such as supportive counselling, relaxation, psychoeducation, pill placebo and treatment as usual. Duration of therapy ranged from five weeks to nine months for symptoms and five weeks to three years for relapse prevention. CBT was given individually or in groups. Participants in symptom studies were in-patients, outpatients or a mixture of both. Various diagnostic criteria and outcome scales were used.

The authors did not state how studies were selected for the review.

Assessment of study quality

The authors did not report a formal validity assessment. Studies with blinded outcome evaluation were considered more rigorous than those with non-blinded assessment.

Data extraction

Data were extracted to derive a standardised mean difference (SMD, Hedges' g) for symptoms and odds ratio (OR) for relapse, both with associated 95% confidence intervals (CIs). Intention-to-treat analysis was used if relevant data were available; otherwise, numbers of patients who completed the study were used.

It appeared that data were extracted by two reviewers and agreed by consensus.

Methods of synthesis

Studies were pooled by meta-analysis using fixed-effect models. Heterogeneity was assessed using the Q-statistic. Subgroup analyses were performed to assess the effect of blinded versus non-blinded outcome evaluation, different control types (psychosocial or pill placebo) and other differences between studies.

Results of the review

Schizophrenia: Nine studies (601 participants) that reported effects on symptoms and eight studies (979 participants) that reported effects on relapse were included.

CBT did not significantly reduce symptoms (SMD -0.076, 95% CI -0.235 to 0.084) or relapse (OR 1.17, 95% CI 0.88 to 1.55). Effect sizes were significantly greater in the two non-blinded studies compared to the seven blinded studies for symptoms (SMD -0.63 versus 0.00, p=0.01); there was no significant effect of blinding on relapse.

Major depression: Nine studies (563 participants) that reported effects on symptoms (Hamilton Depression Scale) and nine studies (881 participants, eight studies with blinded outcome ascertainment) that reported effects on relapse were included.

CBT significantly reduced symptoms overall (SMD -0.282, 95% CI -0.447 to -0.117), but there was no significant effect in studies with a psychosocial control. CBT significantly reduced relapse (OR 0.53, 95% CI 0.40 to 0.71). There was no significant effect of blinding on symptoms; all except one study that examined relapse were blinded.

Bipolar disorder: Four studies (487 participants), all with blinded outcome assessment, compared CBT with treatment as usual for prevention of relapse. CBT did not significantly affect relapse (OR 0.78, 95% CI 0.53 to 1.15). All studies were blinded.

Where reported, statistical heterogeneity was not significant.

Authors' conclusions

CBT was no better than non-specific control interventions for treating schizophrenia and did not reduce relapse rates. It was effective in major depression, but the effect was small in treatment studies. CBT did not appear effective for preventing relapse in bipolar disorder.

CRD commentary

The review addressed a clear question. Inclusion criteria were generally clear, although it was unclear whether only randomised trials were eligible for inclusion. The authors searched a range of relevant sources. Only published studies were included, so the review may have been at risk of publication bias. Methods used for study selection and data extraction were not explicitly reported, so risks of reviewer errors and bias were uncertain.

Although the authors' objective was to review well-controlled trials, no formal assessment of study validity was reported; hence the reliability of the included studies and the synthesis derived from them was uncertain. Study details were reported in an appendix, but there were few details of the interventions, which made it difficult to assess generalisability of the review findings for such a complex intervention as CBT. Studies were pooled by meta-analysis. Clinical and statistical heterogeneity were investigated, but results for statistical heterogeneity were not systematically reported; this made it difficult to assess the appropriateness of pooling the studies in some cases.

The authors' conclusions were in line with the evidence presented. However, limitations in the conduct and/or reporting of the review, particularly lack of validity assessment, suggest that the conclusions should be treated with caution.

Implications of the review for practice and research

The authors did not state any implications for practice or research.

Funding

Instituto de Salud Carlos III, Centro de Investigacion en Red de Salud Mental, CIBERSAM.

Bibliographic details

Lynch D, Laws KR, McKenna PJ. Cognitive behavioural therapy for major psychiatric disorder: does it really work? A meta-analytical review of well-controlled trials Psychological Medicine 2010; 40(1): 9-24. [PubMed: 19476688]

Original Paper URL

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=6778264&fulltextType=RV&fileId=S003329170900590X

Indexing Status

Subject indexing assigned by NLM

MeSH

Adult; Bipolar Disorder /psychology /therapy; Cognitive Therapy /methods; Controlled Clinical Trials as Topic; Depressive Disorder, Major /psychology /therapy; Humans; Psychotic Disorders /psychology /therapy; Recurrence /prevention & control; Schizophrenia /therapy; Schizophrenic Psychology; Treatment Outcome

AccessionNumber

12010001824

Database entry date

02/02/2011

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.