Exercise treatment effect modifiers in persistent low back pain: an individual participant data meta-analysis of 3514 participants from 27 randomised controlled trials

Chronic Low Back Pain IPD Meta-Analysis Group

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BACKGROUND: Low back pain is one of the leading causes of disability worldwide. Exercise therapy is widely recommended to treat persistent non-specific low back pain. While evidence suggests exercise is, on average, moderately effective, there remains uncertainty about which individuals might benefit the most from exercise.

METHODS: In parallel with a Cochrane review update, we requested individual participant data (IPD) from high-quality randomised clinical trials of adults with our two primary outcomes of interest, pain and functional limitations, and calculated global recovery. We compiled a master data set including baseline participant characteristics, exercise and comparison characteristics, and outcomes at short-term, moderate-term and long-term follow-up. We conducted descriptive analyses and one-stage IPD meta-analysis using multilevel mixed-effects regression of the overall treatment effect and prespecified potential treatment effect modifiers.

RESULTS: We received IPD for 27 trials (3514 participants). For studies included in this analysis, compared with no treatment/usual care, exercise therapy on average reduced pain (mean effect/100 (95% CI) -10.7 (-14.1 to -7.4)), a result compatible with a clinically important 20% smallest worthwhile effect. Exercise therapy reduced functional limitations with a clinically important 23% improvement (mean effect/100 (95% CI) -10.2 (-13.2 to -7.3)) at short-term follow-up. Not having heavy physical demands at work and medication use for low back pain were potential treatment effect modifiers-these were associated with superior exercise outcomes relative to non-exercise comparisons. Lower body mass index was also associated with better outcomes in exercise compared with no treatment/usual care. This study was limited by inconsistent availability and measurement of participant characteristics.

CONCLUSIONS: This study provides potentially useful information to help treat patients and design future studies of exercise interventions that are better matched to specific subgroups. PROTOCOL PUBLICATION: https://doi.org/10.1186/2046-4053-1-64.

Original languageEnglish
Article number101205
Pages (from-to)1277-1278
Number of pages16
JournalBritish Journal of Sports Medicine
Issue number21
Early online date28 Nov 2019
Publication statusPublished - 19 Oct 2020

Bibliographical note

© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.


Funding The Nova Scotia Health Research Foundation (NSHRF) (now Research Nova Scotia) funded the early work of the Chronic LBP IPD-Meta-Analysis project. The NSHRF was not involved in any other aspect of the project, such as the design of the project’s protocol and analysis plan, collection and analyses. The funder had no input on the interpretation or publication of the study results. NEF is an NIHR Senior Investigator and was funded through an NIHR Research Professorship (NIHR-RP-011-015). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

FundersFunder number
Nova Scotia Health Research Foundation


    • exercise rehabilitation
    • intervention effectiveness
    • lower back
    • meta-analysis


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