SAT0097 ASSOCIATION BETWEEN PHYSICAL ACTIVITY AND SUBSEQUENT CHANGES IN DISEASE ACTIVITY IN PEOPLE LIVING WITH RHEUMATOID ARTHRITIS

Abstract

Background Various studies have found that rheumatoid arthritis (RA) patients perform less physical activity than the general population, likely due to joint pain and impaired physical function. However, recent studies suggest that physical activity may have a beneficial effect on inflammation and could therefore contribute to reducing RA disease activity. A greater understanding of the relationship between physical activity levels and RA disease activity would be valuable for physical activity counselling of RA patients. Objectives The aim of this study was to evaluate the association between baseline physical activity levels and subsequent changes in measures of disease activity in patients with RA using self-reported data. Methods We conducted a longitudinal study using 2015-2017 data from an annual survey administered to an RA cohort derived from a population-based cohort for BC originally assembled using physician billing data and a previously validated algorithm. Subjects were grouped into three levels (Low, Medium and High) of physical activity (PA) at the baseline year (2015) according to the specifications of the International Physical Activity Questionnaire. We examined whether physical activity at baseline was associated with a change over time in RA disease activity outcomes from 2015 to 2017. We fitted linear mixed models for Rheumatoid Arthritis Disease Activity Index (RADAI), Fatigue visual analog scale (VAS), and Pain VAS scores separately without/with adjusting for age, sex, sociodemographic factors, body mass index, RA duration, physical function (Modified Health Assessment Questionnaire [mHAQ]), smoking, depression and other comorbidities at baseline. Models include the outcome at three years (2015-2017) as the dependent variables, an indicator variable representing the year of measurement (2015-17), PA level at baseline, their interactions, and baseline characteristics as covariates. Models include random effects for subjects to account for correlations among within-subject repeated measures. Missing values were imputed using multiple imputation methods. The analyses were conducted using R 3.5. Results Of the 169 patients who responded to the 2015 survey, 29.6%, 42.0%, and 28.4% had low, medium, and high levels of PA in 2015, respectively. There were no significant differences in RADAI (p=0.67), Fatigue (p=0.78), and Pain (p=0.98) at baseline (Figure 1). The low PA group experienced significant worsening of disease activity outcomes over time, including yearly increases of 0.31 in RADAI (p=0.007), 0.41 in Fatigue (p=0.007), and 0.43 in 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. The interaction terms for PA level and year show that the low PA group had significantly different time trends for RADAI, Fatigue, and Pain compared to the medium and high PA groups (all p values Conclusion Across RADAI, Fatigue VAS, and Pain VAS scores, RA patients with a low PA level demonstrated a significant increase in disease activity over the span of three years. The trends for both the high and medium PA groups differ significantly from that of the low PA group, showing small, overall decreases in disease activity over time. These results add to the accumulating evidence that physical activity may reduce disease activity and is an essential aspect of RA management. Acknowledgement Funded by the CIHR. Disclosure of Interests Kiera Lee-Pii: None declared, Hui Xie: None declared, Yufei Zheng: None declared, Linda Li: None declared, Diane Lacaille Grant/research support from: Bristol-Myers Squibb and Eli Lilly Canada