Associations of joint swelling, joint stiffness, and joint pain with physical activity in first-degree relatives of patients with rheumatoid arthritis

ABSTRACT BackgroundPhysical activity (PA) in pre-clinical rheumatoid arthritis (RA) is associated with lower RA risk and disease severity. Yet, PA in RA patients is less than in counterparts without RA, which can be attributed partly to symptoms of inflammatory arthritis. Therefore, we investigated whether joint swelling, stiffness, or pain were associated with PA in first-degree relatives (FDRs) of RA patients, a population at higher risk for future RA. MethodsWe evaluated associations of joint stiffness, joint swelling, and joint pain with PA time in 268 FDRs with ≥2 visits over an average 1.2 years. Clinicians confirmed joint swelling. Participants self-reported joint stiffness and/or pain. PA during a typical 24-hour day was quantified via questionnaire, weighted to reflect metabolic expenditure, where 24 hours was the minimum PA time. Linear mixed models evaluated associations between symptoms and change in PA over time, adjusting for age, sex, race, body mass index, smoking, and RA-related autoantibodies. ResultsAverage weighted PA time was 37±7 hours. In cross-sectional analysis, PA time was 1.3±0.9 hours higher in FDRs reporting joint pain (p=0.15); and 0.8±1.6 and 0.4±1 hours lower in FDRs with joint swelling (p=0.60) and stiffness (p=0.69), respectively. Longitudinally, adjusting for baseline PA time, baseline symptoms were not significantly associated with changes in PA time. However, on average over time, joint stiffness and pain were associated with lower PA time (pinteraction=0.0002, pinteraction=0.002), and joint swelling was associated with higher PA time (pinteraction<0.0001) ConclusionBaseline symptoms did not predict future PA time, but on average over time, joint symptoms influenced PA time.