Mediators and Moderators of Education Plus Exercise on Perceived Improvement in Individuals With Gluteal Tendinopathy: An Exploratory Analysis of a 3-Arm Randomized Trial

OBJECTIVE:To investigate mediators and moderators of effects of an education-plus -exercise program compared to corticosteroid injections or wait and see on perceived improvement in individuals with gluteal tendinopathy. METHODS:Exploratory analysis from a clinical trial (n = 204) comparing education plus exercise, corticosteroid injection, and wait and see on global rating of change at 52 weeks. Potential mediators measured at baseline and 8 weeks were hip active abduction range, abductor muscle torque, pain self-efficacy, pain constancy, and patient-specific function. Potential moderators at baseline were Victorian Institute of Sport Assessment for gluteal tendinopathy, menopausal status, symptom duration, magnetic resonance imaging-determined tendon pathology, and pain catastrophizing. RESULTS:There is evidence from mediation analysis that the beneficial effect of education plus exercise on global rating of change relative to corticosteroid injection or wait and see may be due to changes in patient-specific function (indirect effect relative risk; 95% CI: 1.14 [1.05-1.29], 1.29 [1.12-1.58], respectively), pain constancy (1.12 [1.03-1.27], 1.2 [1.08-1.41]), and pain self-efficacy (1.1 [1.02-1.25], 1.18 [1.04-1.44])-not active hip movement/muscle torque. Moderation analysis did not support our included patient characteristics. CONCLUSION:Education plus exercise is likely to improve global rating of change for persons with gluteal tendinopathy relative to corticosteroid injection and wait and see through improvements in patient-specific function, pain self-efficacy, and reduced pain constancy. We found no evidence of differences in the effect of education plus exercise in patient subgroups based on disability, menopausal status, symptom duration, tendon pathology, or pain catastrophizing. J Orthop Sports Phys Ther 2022;52(12):826-836. Epub: 17 October 2022. doi:10.2519/jospt.2022.11261

Automated summary

This study investigated the mediators and moderators of the effects of an education-plus-exercise program on perceived improvement in individuals with gluteal tendinopathy. The results indicated that education plus exercise improved the global rating of change through improvements in patient-specific function, pain self-efficacy, and reduced pain constancy.