Background: Cognitive-behavioural therapy aims to increase quality of life by changing cognitive and behavioural factors that maintain problematic symptoms. A previous overview of cognitive-behavioural therapy systematic reviews suggested that cognitive-behavioural therapy was effective for many conditions. However, few of the included reviews synthesised randomised controlled trials.
Objectives: This project was undertaken to map the quality and gaps in the cognitive-behavioural therapy systematic review of randomised controlled trial evidence base. Panoramic meta-analyses were also conducted to identify any across-condition general effects of cognitive-behavioural therapy.
Data sources: The overview was designed with cognitive-behavioural therapy patients, clinicians and researchers. The Cochrane Library, MEDLINE, EMBASE, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, Child Development & Adolescent Studies, Database of Abstracts of Reviews of Effects and OpenGrey databases were searched from 1992 to January 2019.
Review methods: Study inclusion criteria were as follows: (1) fulfil the Centre for Reviews and Dissemination criteria; (2) intervention reported as cognitive-behavioural therapy or including one cognitive and one behavioural element; (3) include a synthesis of cognitive-behavioural therapy trials; (4) include either health-related quality of life, depression, anxiety or pain outcome; and (5) available in English. Review quality was assessed with A MeaSurement Tool to Assess systematic Reviews (AMSTAR)-2. Reviews were quality assessed and data were extracted in duplicate by two independent researchers, and then mapped according to condition, population, context and quality. The effects from high-quality reviews were pooled within condition groups, using a random-effect panoramic meta-analysis. If the across-condition heterogeneity was I2 < 75%, we pooled across conditions. Subgroup analyses were conducted for age, delivery format, comparator type and length of follow-up, and a sensitivity analysis was performed for quality.
Results: A total of 494 reviews were mapped, representing 68% (27/40) of the categories of the International Classification of Diseases, Eleventh Revision, Mortality and Morbidity Statistics. Most reviews (71%, 351/494) were of lower quality. Research on older adults, using cognitive-behavioural therapy preventatively, ethnic minorities and people living outside Europe, North America or Australasia was limited. Out of 494 reviews, 71 were included in the primary panoramic meta-analyses. A modest effect was found in favour of cognitive-behavioural therapy for health-related quality of life (standardised mean difference 0.23, 95% confidence interval 0.05 to 0.41, prediction interval -0.05 to 0.50, I2 = 32%), anxiety (standardised mean difference 0.30, 95% confidence interval 0.18 to 0.43, prediction interval -0.28 to 0.88, I2 = 62%) and pain (standardised mean difference 0.23, 95% confidence interval 0.05 to 0.41, prediction interval -0.28 to 0.74, I2 = 64%) outcomes. All condition, subgroup and sensitivity effect estimates remained consistent with the general effect. A statistically significant interaction effect was evident between the active and non-active comparator groups for the health-related quality-of-life outcome. A general effect for depression outcomes was not produced as a result of considerable heterogeneity across reviews and conditions.
Limitations: Data extraction and analysis were conducted at the review level, rather than returning to the individual trial data. This meant that the risk of bias of the individual trials could not be accounted for, but only the quality of the systematic reviews that synthesised them.
Conclusion: Owing to the consistency and homogeneity of the highest-quality evidence, it is proposed that cognitive-behavioural therapy can produce a modest general, across-condition benefit in health-related quality-of-life, anxiety and pain outcomes.
Future work: Future research should focus on how the modest effect sizes seen with cognitive-behavioural therapy can be increased, for example identifying alternative delivery formats to increase adherence and reduce dropout, and pursuing novel methods to assess intervention fidelity and quality.
Study registration: This study is registered as PROSPERO CRD42017078690.
Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 9. See the NIHR Journals Library website for further project information.
Keywords: COGNITIVE–BEHAVIOURAL THERAPY; DATA ANALYSIS; INTERNATIONAL CLASSIFICATION OF DISEASES; QUALITY OF LIFE.
This report is a summary of research examining if a psychological therapy called cognitive–behavioural therapy can improve the quality of life of people living with physical and/or mental conditions. Cognitive–behavioural therapy uses a set of techniques that help individuals to identify and change problematic thoughts or behaviour patterns that might contribute to and maintain their physical or mental symptoms. It can be delivered face to face or through mediums such as the internet. We aimed to understand if cognitive–behavioural therapy helps patients with specific conditions only, or if it can help patients with any condition. We searched relevant databases to find articles that combine the results from multiple trials testing cognitive–behavioural therapy. These are known as systematic reviews. We graded these reviews as providing good- or poor-quality evidence. We identified the conditions for which we had good-quality evidence on whether or not cognitive–behavioural therapy was helpful. From each review, we took numerical data that told us if cognitive–behavioural therapy improved quality of life for that specific condition. Next, we combined all the numerical data together, across all the conditions, to see if there was a consistent benefit of cognitive–behavioural therapy. The statistical analyses found that cognitive–behavioural therapy consistently improved quality of life across all the conditions where it has been tested. We have evidence that it can help children, adolescents and adults, of either sex, who are living in Europe, North America and Australasia. We are unsure if it will help older adults or people living in Africa, Asia or South America, nor do we know if cognitive–behavioural therapy is equally effective across different ethnic groups. It is recommended that future research should prioritise understanding how cognitive–behavioural therapy works, why some people do not want to use cognitive–behavioural therapy and why some patients do not benefit from it.