Chapter 1
Chapter 1
How Do Nonsurgical Interventions Improve Pain and Physical Function in People With Osteoarthritis? A Scoping Review of Mediation Analysis Studies
Objective. Nonsurgical interventions are recommended for osteoarthritis (O A). However, how interventions change pain and physical function is unclear. Therefore, the objectives of this scoping review were to 1) identify what potential mediators of nonsurgical interventions on pain and physical function have been evaluated and 2) summarize the findings according to intervention, joint, and outcome. Methods. We searched Medline, Embase, CINAHL, Cochrane Central Register of Controlled Trials, and Scopus databases. Studies were included if they conducted a mediation analysis on a randomized controlled trial evaluating a nonsurgical intervention on O A of any joint. Outcomes were pain and physical function. Results. Nine knee O A studies, evaluating diet plus exercise, exercise, unloading shoes, high-expectation communication during acupuncture, and telephone-based weight loss plus exercise were identified. Except for weight loss and self-efficacy, putative mediators (knee muscle perfusion/extensor strength/adduction moment, systemic inflammatory biomarkers, physical activity, dietary intake, and pain beliefs) were evaluated by single studies. Ten mediators partially mediated intervention (diet plus exercise, exercise, high-expectation communication) effects on pain and physical function. Eight mediators were common to pain and function (reduced weight, increased knee extensor strength, and increased self-efficacy). Constant knee flexor muscle perfusion partially mediated exercise effects on pain, and knee pain relief partially mediated exercise effects on function. Conclusion. In knee O A, some evidence suggests that the benefits of 1) diet and exercise are mediated through changes in body weight, systemic inflammation, and self-efficacy; 2) exercise is mediated through changes in knee muscle strength and self-efficacy; and 3) high-expectation communication style is mediated through changes in self-efficacy.
Introduction
Introduction
Osteoarthritis (O A) is a major cause of pain and disability , typically affecting the knees, hips, hands, and feet . Clinical guidelines recommend nonpharmacologic and pharmacologic approaches prior to surgical intervention . However, the mechanism(s) by which many nonsurgical interventions improve pain and physical function remains unclear. With this limited understanding, it is perhaps unsurprising that nonsurgical interventions have, at best, modest clinical benefits and that increasing volumes of patients opt to undergo joint arthroplasty . Understanding the mechanisms that mediate intervention effects can result in more targeted delivery and implementation, in addition to providing the impetus for new treatments or treatment combinations.
One method for understanding how interventions influence outcomes is mediation analysis of a randomized controlled trial (R C T). Mediation analyses can estimate the effect of an intervention on an outcome through an intermediate variable (mediator) by partitioning the total effect into indirect and direct effects .
