Factors Associated with Objectively Measured Physical Activity in Patients with Seropositive Rheumatoid Arthritis

Background: Rheumatoid arthritis (RA) is a chronic autoimmune disease, which is associated with low levels of physical activity (PA). However, the factors related to low physical activity levels have rarely been studied. Methods: In this cross-sectional study, 70 seropositive RA patients were included. Physical activity was objectively assessed with an ActiGraph GT3X+ accelerometer. In addition, body mass index, smoking status, work ability, and clinical parameters (functional disabilities, disease activity, disease duration, pain, and inflammation parameters) were measured. Results: RA patients performed a mean of 215.2 (SD: 136.6) min a week of moderate physical activity and 9.1 (SD: 26.3) min of vigorous physical activity. The total amount of moderate and vigorous physical activity (MVPA) was associated with BMI, and functional disabilities. In addition, non-smokers and patients with better work ability did more MVPA. No association could be seen with disease activity, disease duration, pain, and inflammatory markers. After mutual adjusting of all the variables, only BMI showed a significant relationship with MVPA. Conclusions: RA patients perform de facto no physical activity with vigorous intensity. Factors related to low physical activity are BMI, functional disabilities, workability and smoking status, whereas due to the study design no causal and temporal link could be made.