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Investigating the Causal Mechanisms of Symptom Recovery in Chronic Whiplash Associated Disorders Using Bayesian Networks

Liew, Bernard X.W. PhD*; Scutari, Marco PhD; Peolsson, Anneli PhD; Peterson, Gunnel PhD‡,§; Ludvigsson, Maria Landén PhD‡,∥; Falla, Deborah PhD*

doi: 10.1097/AJP.0000000000000728
Original Article: PDF Only

Objectives: The present study’s objective is to understand the causal mechanisms underpinning the recovery of individuals with whiplash-associated disorders (WAD). We applied Bayesian Networks (BN) to answer two study aims: (1) to identify the causal mechanism(s) of recovery underpinning neck-specific exercise, and (2) quantify if the cyclical pathway of the fear avoidance model (FAM) is supported by the present data.

Methods: We analysed a prospective cohort dataset of 216 individuals with chronic WAD. Fifteen variables were used to build a BN model: treatment group (neck-specific exercise with or without a behavioural approach, or general physical activity), muscle endurance, range of motion, hand strength, neck proprioception, pain catastrophizing, fear, anxiety, depression, self-efficacy, perceived work ability, disability, pain intensity, sex, and follow-up time.

Results: The BN model showed that neck pain reduction rate was greater after neck-specific exercise compared to physical activity prescription (β=0.59 points/month [P<0.001]) only in the presence of two mediators: global neck muscle endurance and perceived work ability. We also found the following pathway of variables that constituted the FAM: anxiety, followed by depressive symptoms, fear, catastrophizing, self-efficacy, and consequently pain.

Conclusion: We uncovered two mediators which explained the mechanisms of effect behind neck-specific exercise, and proposed an alternative FAM pathway. The present study is the first to apply BN modelling to understand the causal mechanisms of recovery in WAD. In doing so, it is anticipated that such analytical methods could increase the precision of treatment in individuals with chronic WAD.

*Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom

Department of Statistics, University of Oxford, Oxford, United Kingdom

Department of Medical and Health Sciences, Division of Physiotherapy, Linköping University, Linköping, Sweden

§Centre for Clinical Research Sörmland, Uppsala University, Uppsala, Sweden

Rehab Väst, County Council of Östergötland, Department of Rehabilitation and Department of Medical and Health, Sweden

Trials registration: identifier: NCT01528579.

Disclosures: This study was supported by funding from the Swedish government through the REHSAM Foundation, the Swedish Research Council, the regional Center for Clinical Research and the County Council of Östergötland, Centre for Clinical Research Sörmland at Uppsala University, the Medical Research Council of Southeast Sweden, and the Uppsala-Örebro Regional Research Council, Sweden. The authors declare no conflicts of interest.

Conflicts of interest: The authors have no conflicts of interest to declare.

Reprints: Bernard Liew, PhD, School of Sport, Exercise and Rehabilitation Sciences, Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom (e-mail:

Received January 15, 2019

Received in revised form May 8, 2019

Accepted May 16, 2019

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