Link Between Positive Clinician-Conveyed Expectations of Treatment Effect and Pain Reduction in Knee Osteoarthritis, Mediated by Patient Self-Efficacy

Objective: A prior knee osteoarthritis (OA) trial found that provider-conveyed expectations for treatment success were associated with pain improvement. We hypothesized this relationship was mediated by patient self-efficacy, since expectations of improvement may enhance one's ability to control health behaviors, and therefore health. Our aim was to examine whether self-efficacy was a mediator of the relationship observed in this trial. Methods: A secondary analysis of a 3-arm (traditional acupuncture, sham acupuncture, and wait list) trial for knee OA was conducted. Those in the acupuncture groups were equally randomized to acupuncturists trained to communicate a high or neutral expectation of treatment success (e.g., using language conveying high or unclear likelihood that acupuncture would reduce knee pain). A modified Arthritis Self-Efficacy Questionnaire and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale were administered. Linear regression analyses were used to examine whether patient self-efficacy mediated the relationship between provider communication style and knee pain at 3 months. Results: High-expectation provider communication was associated with patient self-efficacy, β coefficient of 0.14 (95% confidence interval [95% CI] 0.01, 0.28). Self-efficacy was associated with WOMAC pain, β coefficient of −9.29 (95% CI −11.11, −7.47), while controlling for the provider communication style. The indirect effect a × b of −1.36 for high versus neutral expectation (bootstrap 95% CI −2.80, −0.15; does not include 0), supports the conclusion that patient self-efficacy mediates the relationship between provider-communicated expectations of treatment effects and knee pain. Conclusion: Our findings suggest that clinician-conveyed expectations can enhance the benefit of treatments targeting knee OA symptoms, mediated by improved patient self-efficacy.