Association between physical activity and subsequent changes in disease activity in people living with rheumatoid arthritis

Various studies have demonstrated how rheumatoid arthritis (RA) patients perform less physical activity than the general population, likely due to joint pain and impaired physical function. However, physical activity (PA) may have beneficial effects on reducing inflammation and RA disease activity. The objective of this study was to evaluate the association between baseline PA levels and self-reported changes in measures of RA disease activity. We conducted a longitudinal study using 2015-2017 data from an annual survey administered to an RA cohort in BC. Subjects were grouped into three levels (Low, Medium and High) of PA at the baseline year (2015) according to the specifications of the International Physical Activity Questionnaire. Subsequently, we examined whether baseline PA was associated with changes in RA disease activity outcomes over 2015 to 2017, using fitted linear mixed models for each measure and adjusting for age, sex and other covariates. Of the 169 patients who responded to the 2015 survey, 29.6%, 42.0%, and 28.4% were grouped into Low, Medium, and High levels of PA, respectively. Our results demonstrated that the Low PA group experienced significant worsening of disease activity outcomes over the three years, including those of the Rheumatoid Arthritis Disease Activity Index (RADAI) (p=0.007), Fatigue (p=0.007), and Pain (p=0.007). Those in the Medium and High PA groups at baseline experienced either a decrease or no change in their disease activity outcomes over time. These results add to the accumulating evidence that physical activity may reduce disease activity and is essential to RA management.