Mindfulness Based Stress Reduction (MBSR) for Improving Health, Quality of Life, and Social Functioning in Adults

Abstract

Executive summary/Abstract BACKGROUND Stress and distress are common experiences central to many of the problems occupying health and social services and efforts to improve both health and quality of life are receiving increasing attention. Evaluative research on mind-body interventions is also growing and one of the best studied efforts to reduce stress is mindfulness-based stress reduction (MBSR). Developed by Kabat-Zinn in 1979, MBSR is based on old spiritual traditions and includes regular meditation. Mindfulness is a way of intentionally attending to the present moment in a non-judgemental way. A number of reviews and meta-analyses on MBSR have been conducted, but few have adhered to the meta-analytic protocol stipulated by the Cochrane and Campbell collaborations. The last review of all relevant target groups was published in 2004. OBJECTIVES To evaluate the effect of mindfulness-based stress reduction (MBSR) on health, quality of life, and social functioning in adults. SEARCH STRATEGY We searched all relevant databases: MEDLINE, AMED, PsycINFO, EMBASE, Ovid Nursing Full Text Plus, the British Nursing Index and Archive, the Cochrane Central Register of Controlled Trials (CENTRAL), SIGLE, Web of Science®, SveMed+, Dissertation Abstracts International, ERIC, Social Services Abstracts, Sociological Abstracts, the International Bibliography of Social Sciences, and ProQuest. The searches were conducted in July 2008 and again in September 2010. SELECTION CRITERIA Randomised controlled trials on all target groups were included where the intervention followed the MBSR protocol developed by Kabat-Zinn, allowing for variations in the length of the MBSR courses.We accepted all types of control groups and no language restrictions were imposed. DATA COLLECTION AND ANALYSIS Two reviewers independently read the titles, retrieved the studies, and extracted data from all the included studies. We calculated standardised mean differences (expressed as Hedges’ g-values) from all of the study outcomes using Comprehensive Meta Analysis. The meta-analyses were undertaken using the Metafor Package which is part of the statistical program ‘R’; we used a newly developed technique (Robust Standard Errors) to address the statistical challenge presented by clusters of internally correlated effect estimates. RESULTS We identified 31 RCTs with an overall total of 1,942 participants. Seven studies included people with mild to moderate psychological problems, 13 studies targeted people with various somatic conditions, and 11 studies recruited people from the general population. 26 of the 31 RCTs were used for the meta-analyses (an overall total of 1,456 persons). All effect sizes are expressed using Hedges’ g-values, and positive values indicate beneficial effects. Post-intervention effect sizes were as follows: for measures of anxiety 0.53 (95% CI 0.43, 0.63), for depression 0.54 (95% CI 0.35, 0.74), and for stress/distress 0.56 (95% CI 0.44, 0.67). The overall effect size post-intervention for the combined outcome ‘mental health’ was 0.53 (95% CI -0.43, 0.64). Heterogeneity was low and tau square-values (for between-study variance) ranged from 0 to 0.03. The results for measures of personal development were 0.50 (95% CI 0.35, 0.66), quality of life 0.57 (95% CI 0.17, 0.96), mindfulness 0.70 (95% CI 0.05, 1.34), and somatic health 0.31 (95% CI 0.10, 0.52). Results for quality of life and mindfulness showed moderate to large heterogeneity. Effect sizes for the combined mental health outcomes were relatively similar across the range of target groups: 0.50 for clinical and 0.62 for non-clinical populations and this difference is not significant. Likewise the effect size was 0.51 both for people recruited because of a somatic condition and for those with a mental health problem. Effect sizes for mental health were not particularly influenced by the length of intervention, self-reported practice, risk of bias, or whether analyses were done as intention to treat or per protocol, but they were positively correlated with course attendance. Only nine studies included follow-up data; the effects diminished over time except in one study in which refresher classes were held. Very little data were found on social functioning, and no information at all on side effects and costs. AUTHORS’ CONCLUSIONS MBSR has a moderate and consistent effect on a number of measures of mental health for a wide range of target groups. It also appears to improve measures of personal development such as empathy and coping, and enhance both mindfulness, quality of life and improve some aspects of somatic health. Hardly any included studies measured either social function or work ability. There is a paucity of data on long-term effects.