Musculoskeletal shoulder pain: Home exercise frequency and adherence to appointments are not mediators of outcome

Objective: To investigate whether appointment adherence and frequency of home exercises mediates the association of baseline i) pain self-efficacy (PSE) or ii) patient expectation of recovery, with outcome at 6 months. Design: Multicentre longitudinal cohort study. Methods: Six-month outcome data (SPADI, QuickDASH) were provided by 810 of 1030 recruited participants. Daily frequency of home exercises over 6 weeks, were expressed as the proportion of days exercises were completed. Measures of adherence included proportion of appointments attended and completing a course of physiotherapy. Mediation analyses were conducted using Baron and Kennys' four-step method, and for continuous variables, testing the indirect effect using a non-parametric version of Sobel's test. Results: Appointment adherence, completing a course of physiotherapy and frequency of home exercise did not mediate the relationship between PSE or patient expectation with 6 months SPADI or QuickDASH. Higher PSE was significantly associated with appointment adherence and completing a course of physiotherapy. Patient expectation was significantly associated with frequency of home exercise. However, none of the hypothesised mediators had a significant effect on outcome. Conclusion: Appointment adherence and higher frequency of home exercise do not appear to be the mechanisms by which high PSE or expectation of recovery predict a good outcome. This study was not designed to address the effectiveness of a home exercise programme for which no conclusions should be drawn. However, our results do support the need for a greater emphasis on the assessment and incorporation of techniques to facilitate high pain self-efficacy and expectation of recovery.