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Exercise treatment effect modifiers in persistent low back pain: an individual participant data meta-analysis of 3514 participants from 27 randomised controlled trials
  1. Jill A Hayden1,
  2. Maria N Wilson1,
  3. Samuel Stewart1,
  4. Jennifer L Cartwright1,
  5. Andrea O Smith1,
  6. Richard D Riley2,
  7. Maurits van Tulder3,
  8. Tom Bendix4,
  9. Francesca Cecchi5,
  10. Leonardo O P Costa6,
  11. Ninna Dufour7,
  12. Manuela L Ferreira8,
  13. Nadine E Foster9,
  14. Maruti R Gudavalli10,
  15. Jan Hartvigsen11,
  16. Pieter Helmhout12,
  17. Jan Kool13,
  18. George A Koumantakis14,
  19. Francisco M Kovacs15,
  20. Tiina Kuukkanen16,
  21. Audrey Long17,
  22. Luciana G Macedo18,
  23. Luciana A C Machado19,
  24. Chris G Maher20,
  25. Wolf Mehling21,
  26. Giovanni Morone22,
  27. Tom Peterson23,
  28. Eva Rasmussen-Barr24,
  29. Cormac G Ryan25,
  30. Tuulikki Sjögren26,
  31. Rob Smeets27,
  32. J Bart Staal28,
  33. Monica Unsgaard-Tøndel29,
  34. Henry Wajswelner30,
  35. Ella W Yeung31
  36. On behalf of Chronic Low Back Pain IPD Meta-Analysis Group
  1. 1 Department of Community Health and Epidemiology, Dalhousie University, Halifax, Nova Scotia, Canada
  2. 2 Research Institute for Primary Care and Health Sciences, Keele University, Keele, UK
  3. 3 Department of Health Sciences, VU University, Amsterdam, The Netherlands
  4. 4 Center for Rheumatology and Spine Diseases, Rigshospitalet, and University of Copenhagen, Copenhagen, Denmark
  5. 5 Fondazione Don Carlo Gnocchi, Scientific Institute, Florence, Italy
  6. 6 Masters and Doctoral Programs in Physical Therapy, Universidade Cidade de Sao Paulo, Sao Paulo, Brazil
  7. 7 Department of Rheumatology, A2 Rheumatology and Sports Medicine, Hillerød, Denmark
  8. 8 Institute of Bone and Joint Research, The Kolling Institute, University of Sydney, Sydney Medical School, Sydney, New South Wales, Australia
  9. 9 Primary Care Centre Versus Arthritis, School for Primary, Community and Social Care, Keele University, Keele, Staffordshire, UK
  10. 10 College of Chiropractic Medicine, Keiser University, West Palm Beach, Florida, USA
  11. 11 Department of Sports Science and Clinical Biomechanics, University of Southern Denmark; Nordic Institute of Chiropractic and Clinical Biomechanics, Odense, Denmark
  12. 12 Department of Training Medicine and Training Physiology, Personnel Command, Royal Netherlands Army, Utrecht, The Netherlands
  13. 13 Research Department and Department of Rheumatology, Rehabilitation Centre Valens, Valens, Switzerland
  14. 14 Centre for Rehabilitation Science, University of Manchester, Manchester Royal Infirmary, Manchester, UK
  15. 15 Unidad de la Espalda Kovacs, Hospital Universitario HLA-Moncloa, Red Española de Investigadores en Dolencias de la Espalda, Madrid, Spain
  16. 16 School of Health and Social Studies, JAMK University of Applied Sciences, Jyväskylä, Finland
  17. 17 Bonavista Physical Therapy, Calgary, Alberta, Canada
  18. 18 School of Rehabilitation Science, McMaster University, Hamilton, Ontario, Canada
  19. 19 University Hospital, UFMG-Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
  20. 20 Institute for Musculoskeletal Health, Sydney School of Public Health, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
  21. 21 Department of Family and Community Medicine, University of California San Francisco, San Francisco, California, USA
  22. 22 Clinical Laboratory of Experimental Neurorehabilitation, Santa Lucia Foundation, Rome, Italy
  23. 23 Back Center Copenhagen, Copenhagen, Denmark
  24. 24 Department of Neurobiology Care Sciences, and Society, Division of Physiotherapy, Karolinska Institutet, Huddinge, Sweden
  25. 25 School of Health and Life Sciences, Teesside University, Middlesbrough, UK
  26. 26 Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
  27. 27 Department of Rehabilitation Medicine, Research School of CAPHRI, Maastricht University, Maastricht, The Netherlands
  28. 28 Radboud Institute for Health Sciences, IQ Healthcare, Radboud University Medical Center, Nijmegen, The Netherlands
  29. 29 Department of Neuromedicine and Movement Science, and Department of Public Health and Nursing, NTNU, Trondheim, Norway
  30. 30 Discipline of Physiotherapy, School of Allied Health, Human Services and Sport, College of Science, Health and Engineering, La Trobe University, Melbourne, Victoria, Australia
  31. 31 Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Kowloon, Hong Kong
  1. Correspondence to Dr Jill A Hayden, Community Health and Epidemiology, Dalhousie University, Halifax, Halifax, NS B3H 4R2, Canada; jhayden{at}


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.

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

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  • Collaborators Chronic Low Back Pain IPD Meta-Analysis Group (in alphabetical order): T Bendix, F Cecchi, LOP Costa, N Dufour, ML Ferreira, NE Foster, MR Gudavalli, J Hartvigsen, P Helmhout, J Kool, G Koumantakis, F Kovacs, T Kuukkanen, A Long, L Macedo, LA Machado, CG Maher, W Mehling, G Morone, T Petersen, E Rasmussen-Barr, CG Ryan, T Sjögren, R Smeets, JB Staal, M Unsgaard-Tøndel, H Wajswelner and EW Yeung.

  • Contributors JAH conceived the protocol. JAH and JC developed and drafted the initial protocol with input from RR and MvT. JC, AOS and MNW tested and mapped the data variables. JAH, MNW and SS conducted analyses with guidance from RR. The members of the Chronic LBP IPD Meta-Analysis Group contributed IPD and guidance to this study. JAH and MNW drafted the initial manuscript. All members of the Chronic LBP IPD Meta-Analysis Group were sent draft versions of the protocol and manuscript and were invited to comment and contribute changes. All authors approved the final protocol manuscript.

  • 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.

  • Competing interests MvT and the members of the Chronic LBP IPD Meta-analysis Group are investigators of the individual trials included in the IPD data set.

  • Patient consent for publication Not required.

  • Ethics approval This IPD study was approved by the Dalhousie University Research Ethics Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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