Reduced physical activity in children and adolescents with Juvenile Idiopathic Arthritis despite satisfactory control of inflammation

Background: Vascular health is of concern in patients with Juvenile Idiopathic Arthritis (JIA) since Rheumatoid Arthritis (RA) epidemiologically has a well-described association with premature development of atherosclerosis. Chronic inflammation with persisting systemic circulating inflammatory proteins may be a cause of vascular damage, but general physical inactivity could be an important contributor. Pain and fatigue are common complaints in patients with JIA and may well lead to an inactive sedentary lifestyle. For this reason we assessed the physical activity (PA) objectively in patients with moderate to severe Juvenile Idiopathic Arthritis (JIA) in comparison with gender and age matched healthy schoolchildren, and looked for associations between PA and features of JIA. Methods: One hundred thirty-three patients, 7-20 years of age, participated. Disease activity, disability, functional ability, and pain were assessed and PA was measured by accelerometry through 7 days and compared to PA in age-and gender-matched healthy schoolchildren. Results: We found a significantly lower level of PA in patients compared to gender-and age-matched healthy schoolchildren both in average activity (counts per minute, cpm) (475.6 vs. 522.7, p = 0.0000018) and in minutes per day spent with cpm > 1500 (67.9 vs. 76.4, p = 0.0000014), with cpm > 2000 (moderate physical activity) (48.4 vs. 52.8, p = 0.0001, and with cpm > 3000 (high physical activity) (24.7 vs. 26.5, p = 0.00015). A negative association (beta = -0.213, p = 0.014) between active disease in weight bearing joints and high physical activity remained the only significant association between disease related factors and PA. Of the girls 19 % and of the boys 45 % (vs. 39 % and 61 % in the reference group) met standards set by Danish Health Authorities for daily PA in childhood. Conclusion: Children and adolescents with JIA are less physically active than their healthy peers and less active than recommended for general health by the Danish Health Authorities. This is not explained by pain or objective signs of inflammation. When inflammation has been curbed, restoration of an active healthy lifestyle should be highly prioritized.