The mechanisms of effect of a physiotherapist-delivered integrated psychological and exercise intervention for acute whiplash-associated disorders: secondary mediation analysis of a randomized controlled trial

R.A. Elphinston*, M. Sterling, J. Kenardy, R. Smeets, N.R. Armfield

*Corresponding author for this work

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Introduction:Integrated psychological and physical treatments can improve recovery for whiplash-associated disorders (WADs). Little is known about how these interventions work.Objective:To examine the mechanisms by which a physiotherapist-delivered integrated intervention for acute WAD improves health outcomes.Methods:Secondary analysis using structural equation modelling of a randomized controlled trial comparing integrated stress inoculation training and exercise to exercise alone for acute WAD. Outcomes were disability, pain self-efficacy, pain intensity, and health-related quality of life at 12 months. The intended intervention target and primary mediator, stress was tested in parallel with pain-related coping, an additional cognitive behavioral mediator that significantly improved at posttreatment (Model 1). Stress-related constructs that commonly co-occur with stress and pain were also tested as parallel mediators: depression and pain-related coping (Model 2); and posttraumatic stress and pain-related coping (Model 3).Results:Reductions in stress mediated the effect of the integrated intervention on disability (beta = -0.12, confidence interval [CI] = -0.21 to -0.06), pain self-efficacy (beta = 0.09, CI = 0.02-0.18), pain (beta = -0.12, CI = -0.21 to -0.06), and health-related quality of life (beta = 0.11, CI = 0.04-0.21). There was an additional path to pain self-efficacy through pain-related coping (beta = 0.06, CI = 0.01-0.12). Similar patterns were found in Models 2 and 3.Conclusions:Improvements in stress and related constructs of depression and posttraumatic stress, and pain-related coping were causal mechanisms of effect in a physiotherapist-delivered integrated intervention. As integrated interventions are growing in popularity, it is important to further personalize interventions for improved benefit.
Original languageEnglish
Number of pages10
JournalPain reports
Issue number5
Publication statusPublished - 1 Sept 2020


  • Integrated interventions
  • Cognitive behavioral therapy
  • Physical rehabilitation
  • Physiotherapy
  • Whiplash
  • Change processes
  • WAD

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