Factors Associated with Adherence To a Supervised Exercise Intervention for Osteoarthritis: Data From the Swedish Osteoarthritis Registry

OBJECTIVE: To explore how lifestyle and demographic, socioeconomic and disease-related factors are associated with supervised exercise adherence in an osteoarthritis (OA) management programme and their ability to explain exercise adherence.METHODS: A cohort register-based study on participants from the 'Swedish Osteoarthritis Registry' who attended the exercise part of a nationwide Swedish OA management programme. We ran a multinomial logistic regression to determine the association of exercise adherence with the abovementioned factors. We calculated their ability to explain exercise adherence with the McFadden R2 .RESULTS: Our sample comprises 19,750 (73% female sex; age: 67 (SD: 8.94)) participants. Among them, 5,862 (30%) reached a low level of adherence, 3,947 (20%) a medium level and 9,941 (50%) a high level. After a listwise deletion, the analysis was run on n=16,685 (85%), with low levels of adherence as the reference category. Some factors were positively associated with high levels of adherence, such as older age (relative risk ratio (RRR) =1.01, 95% CI 1.01-1.02 (per year)), and the 'arthritis-specific self-efficacy' (1.04, 95% CI 1.02-1.07 (per 10-point increase)). Others were negatively associated with high levels of adherence, such as 'female' sex (0.82, 95% CI [0.75-0.89]), having a 'medium' (0.89, 95% CI [0.81; 0.98] or a 'high' level of education (0.84, 95% CI [0.76-0.94]). Nevertheless, the investigating factors could explain 1% of the variability in exercise adherence (R2 = 0.012).CONCLUSION: Despite the associations reported above, the low-explained variability suggests that strategies based on lifestyle and demographic, socioeconomic and disease-related factors are unlikely to improve exercise adherence significantly.