Which Exercise for Low Back Pain? (WELBack) trial predicting response to exercise treatments for patients with low back pain: a validation randomised controlled trial protocol.

INTRODUCTION: Exercise therapy is the most recommended treatment for chronic low back pain (LBP). Effect sizes for exercises are usually small to moderate and could be due to the heterogeneity of people presenting with LBP. Thus, if patients could be better matched to exercise based on individual factors, then the effects of treatment could be greater. A recently published study provided evidence of better outcomes when patients are matched to the appropriate exercise type. The study demonstrated that a 15-item questionnaire, the Lumbar Spine Instability Questionnaire (LSIQ), could identify patients who responded best to one of the two exercise approaches for LBP (motor control and graded activity). The primary aim of the current study isill be to evaluate whether preidentified baseline characteristics, including the LSIQ, can modify the response to two of the most common exercise therapies for non-specific LBP. Secondary aims include an economic evaluations with a cost-effectiveness analysis. METHODS AND ANALYSIS: Participants (n=414) will be recruited by primary care professionals and randomised (1:1) to receive motor control exercises or graded activity. Participants will undergo 12 sessions of exercise therapy over an 8-week period. The primary outcome will be physical function at 2 months using the Oswestry Disability Index. Secondary outcomes will be pain intensity, function and quality of life measured at 2, 6 and 12 months. Potential effect modifiers will be the LSIQ, self-efficacy, coping strategies, kinesiophobia and measures of nociceptive pain and central sensitisation. We will construct linear mixed models with terms for participants (fixed), treatment group, predictor (potential effect modifier), treatment group×predictor (potential effect modifier), physiotherapists, treatment group×physiotherapists and baseline score for the dependent variable. ETHICS AND DISSEMINATION: This study received ethics approval from the Hamilton Integrate Research Ethics Board. Results will be submitted for publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT04283409.

Validating self-report measures of pain and function in patients undergoing hip or knee arthroplasty.

PURPOSE: To investigate the factorial and construct validity of a four-item pain intensity scale, the P4, in patients awaiting primary total hip or knee arthroplasty secondary to osteoarthritis. METHOD: A construct validation design was applied to a sample of convenience of 117 patients (mean age 65.6 [SD = 11.2] years) at their preoperative visit. All patients completed the P4 and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Exploratory and confirmatory factor analyses were used to examine the factorial structure of the P4 and WOMAC. To evaluate construct validity, we examined the correlation between the P4 and WOMAC pain sub-scales and the ability of the P4 to differentiate between patients awaiting hip and knee replacement. RESULTS: Two distinct factors consistent with the themes of pain and function were identified with P4 and WOMAC physical function items, but not with the WOMAC pain and physical function items. The P4 correlates more with the WOMAC pain scores (r = 0.67) than with the WOMAC physical function scores (r = 0.60). CONCLUSION: The P4's validity was supported in this patient group. The use of the P4 with the WOMAC physical function sub-scale provides a more distinct assessment of pain and function than the WOMAC pain and physical function scales.