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Individual participant data systematic review and meta-analysis of randomised controlled trials assessing adult mindfulness-based programmes for mental health promotion in non-clinical settings.

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Friedrich, Claire 
Collaboration of Mindfulness Trials (CoMinT) 3 


INTRODUCTION: Mindfulness-based programmes (MBPs) are widely used to prevent mental ill-health that is becoming the leading global cause of morbidity. Evidence suggests beneficial average effects but wide variability. We aimed to confirm the effect of MBPs on psychological distress, and to understand whether and how baseline distress, gender, age, education, and dispositional mindfulness modify the effect of MBPs on distress among adults in non-clinical settings. METHODS: We conducted a pre-registered systematic review and individual participant data (IPD) meta-analysis (PROSPERO CRD42020200117). Thirteen databases were searched in December 2020 for randomised controlled trials satisfying a quality threshold and comparing in-person, expert-defined MBPs in non-clinical settings with passive control groups. Two researchers independently selected, extracted, and appraised trials using the revised Cochrane Risk-of-Bias Tool (RoB2). Anonymised IPD of eligible trials were sought from collaborating authors. The primary outcome was psychological distress (unpleasant mental or emotional experiences including anxiety and depression) at 1 to 6 months after programme completion. Data were checked and imputed if missing. Pairwise, random-effects, two-stage IPD meta-analyses were conducted. Effect modification analyses followed a within-studies approach. Public and professional stakeholders were involved in the planning, conduct and dissemination of this study. RESULTS: Fifteen trials were eligible, 13 trialists shared IPD (2,371 participants representing 8 countries, median age 34 years-old, 71% women, moderately distressed on average, 20% missing outcome data). In comparison with passive control groups, MBPs reduced average distress between one- and six-months post-intervention with a small to moderate effect size (standardised mean difference (SMD) -0.32; 95% confidence interval (CI) -0.41 to -0.24; p-value < 0.001; 95% prediction interval (PI) -0.41 to -0.24 (no heterogeneity)). Results were robust to sensitivity analyses, and similar for the other psychological distress time point ranges. Confidence in the primary outcome result is high. We found no clear indication that this effect is modified by baseline psychological distress, gender, age, education level, or dispositional mindfulness. CONCLUSIONS: Group-based teacher-led MBPs generally reduce psychological distress among community adults who volunteer to receive this type of intervention. More research is needed to identify sources of variability in outcomes at an individual level.


Acknowledgements: We are very grateful to those in our professional and public stakeholder groups for their keen involvement. This publication presents independent research funded by the UK National Institute for Health Research (NIHR). The views expressed are those of the authors and not necessarily those of the UK National Health Service (NHS), the NIHR, or the Department of Health and Social Care. All research from the Department of Psychiatry at the University of Cambridge is supported by the NIHR Cambridge Biomedical Research Centre (BRC-1215-20014) and the NIHR East of England Applied Research Centre. J.G. is funded by an NIHR post-doctoral fellowship for this research project (PDF-2017-10-018, salary and all project costs). C.F.’s salary for this research project was funded by a Cambridgeshire and Peterborough NHS Foundation Trust grant awarded to J.G. I.R.W. was supported by the UK Medical Research Council Programme MC_UU_00004/06. T.D. was supported by the UK Medical Research Council (SUAG/043 G101400), the Wellcome Trust (104908/Z/14/Z, 107496/Z/15/Z), and the NIHR Cambridge Biomedical Research Centre. P.B.J. is supported by the Wellcome Trust (095844/Z/11/Z), the UK Medical Research Council (MR/N019067/1), and the NIHR ARC East of England. S.B.G. was supported by the National Center for Complementary and Integrative Health of the National Institutes of Health under Award Number K23AT010879 and by the Hope for Depression Research Foundation ‘Defeating Depression’ Award. Funders for the trials with data shared for inclusion in the IPD meta-analysis were as follows: the University of Newcastle and the University of Phayao64; the NIH National Center for Complementary and Alternative Medicine and the Clinical and Translational Science Award Program of the NIH National Center for Research Resources 104–110; the National Institutes of Health and National Center for Complementary and Alternative Medicine111–116; the National Center for Complementary and Integrative Health of the National Institutes of Health117–119; Fundación Científica y Tecnológica de la Asociación Chilena de Seguridad120; the University of Cambridge and the National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care East of England39, 121–123; the Health Promotion Administration and the Ministry of Health and Welfare124; the Teachers Health Foundation125; the National Center for Complementary and Integrative Health and the National Institute of Mental Health (NIMH) and the Fetzer Institute; the John Templeton Foundation and the Waisman Center from the National Institute of Child Health and Human Development65, 126–128; the Alberta Children’s Hospital Foundation and the Alberta Center for Child, Family and Community Research and the Alberta Family Wellness Initiative66, 129; the Foundation Alpe d’Huzes and the Dutch Cancer Society30, 130, 131; the Horizon 2020 Marie Sklodowska-Curie Innovative Training Networks grant and with additional support from MIND Netherland and Karakter Child and Adolescent Psychiatry67, 132; and the Departments of Psychiatry and of Primary and Community Care and the Health Academy of the Radboudumc71, 133. The funders had no role in the study design or data collection.

Funder: Cambridgeshire & Peterborough NHS Foundation Trust

Funder: Hope for Depression Research Foundation (Depression Research Foundation); doi:


Collaboration of Mindfulness Trials (CoMinT) 3, Collaboration of Mindfulness Trials (CoMinT)

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Nat Ment Health

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Springer Science and Business Media LLC
Wellcome Trust (095844/Z/11/Z)
Medical Research Council (MR/N019067/1)
Wellcome Trust (via University of Oxford) (107496/Z/15/Z?)
National Institute for Health and Care Research (IS-BRC-1215-20014)
Wellcome Trust (104908/Z/14/Z)
MRC (MC_UU_00030/5)