Can we identify how programmes aimed at promoting self-management in musculoskeletal pain work and who benefits? A systematic review of sub-group analysis within RCTs

Background: There are now several systematic reviews of RCTs testing self-management for those with chronic musculoskeletal pain. Evidence for the effectiveness of self-management interventions in chronic musculoskeletal pain is equivocal and it is not clear for which sub-groups of patients SM is optimally effective. Aims: To systematically review randomized controlled trials of self-management for chronic musculoskeletal pain that reported predictors, i.e., 'baseline factors that predict outcome independent of any treatment effect'; moderators, i.e., 'baseline factors which predict benefit from a particular treatment'; or mediators i.e., 'factors measured during treatment that impact on outcome' of outcome. Method: We searched relevant electronic databases. We assessed the evidence according to the methodological strengths of the studies. We did meta-regression analyses for age and gender, as potential moderators. Results: Although the methodological quality of primary trials was good, there were few relevant studies; most were compromised by lack of power for moderator and mediator analyses. We found strong evidence that self-efficacy and depression at baseline predict outcome and strong evidence that pain catastrophizing and physical activity can mediate outcome from self-management. There was insufficient data on moderators of treatment. Conclusions: The current evidence suggests four factors that relate to outcome as predictors/mediators, but there is no evidence for effect moderators. Future studies of mediation and moderation should be designed with 'a priori' hypotheses and adequate statistical power. (C) 2011 Published by Elsevier Ltd. on behalf of European Federation of International Association for the Study of Pain Chapters