At six months, the primary outcome showed no significant differences in the change in average pain (mean difference 0.4 unit [95% (confidence interval [CI]) 20.4, 1.3]) or physical function (WOMAC: 1.8 units [95% CI 21.9, 5.5]) between the two groups. However, both groups did show clinically relevant improvements from baseline. “These improvements were generally maintained over 18 months,” write the authors. “Improvements at this time point were of an order of magnitude of 42–54% for function, which far exceeds the minimum clinically important difference [MCID] in both groups, and 26–36% for pain, attaining the MCID only in the physiotherapy plus coaching group.”
For secondary outcomes, there were no between-group differences for changes in NRS walking pain, WOMAC pain or quality of life scores at any time point. Although some secondary outcomes related to physical activity and exercise behavior favored the physiotherapy plus coaching group at six months, this difference was not significant at 12 or 18 months.
Adherence: Participants in the physiotherapy plus coaching group had greater adherence during the six-month intervention than the physiotherapy-only group (mean 69% [95% CI 63, 75] vs. mean 55% [95% CI 47, 63]). However, this difference was not maintained at 12 and 18 months. During the intervention, self-rated home exercise adherence using NRS was also higher in the physiotherapy plus coaching group than in the physiotherapy-only group (mean 7.4 [95% CI 6.9, 7.8] vs. mean 5.7 [95% CI 4.9, 6.4]). But again, this difference was not maintained at 12 and 18 months.
In their discussion, researchers note, “The adherence levels needed to affect pain and function are unknown … and greater differences in adherence [between the groups] may be required.” The researchers also suggest that health coaching may be more effective if it begins after physiotherapy visits stop, which is when adherence levels fell to approximately 40%.
Bennell KL, Campbell PK, Egerton T, et al. Telephone coaching to enhance a home-based physical activity program for knee osteoarthritis: A randomized clinical trial. Arthritis Care Res (Hoboken). 2017 Jan;69(1):84–94. doi: 10.1002/acr.22915.