Adiposity is related to inflammatory disease activity in juvenile idiopathic arthritis

Abstract

Objective: To identify factors associated with the higher proportion of fatty tissue and overweight/obesity observed in patients with juvenile idiopathic arthritis (JIA). Patients and methods: We performed a cross‐sectional study of 80 JIA patients aged 4–15 years with 80 age‐ and sex‐matched healthy controls. Body composition was assessed using dual‐energy x‐ray absorptiometry. The 27‐joint Juvenile Arthritis Disease Activity score (JADAS27) was calculated. Two multivariate models were constructed to identify factors associated with overweight/obesity and fat mass index (FMI). Results: No differences were found between cases and controls in body mass index (BMI) or body composition. However, compared with controls, patients with a high inflammatory activity (JADAS27 > 4.2 for oligoarticular JIA or >8.5 for polyarticular disease) had higher values for BMI (p = 0.006); total fat mass (p = 0.003); FMI (p = 0.001); and fat in the legs (p = 0.001), trunk (p = 0.001), and arms (p = 0.002). The factors associated with overweight/obesity in patients were the duration of therapy with biological drugs, measured in months (OR [95% CI] = 1.12 [1.02–1.04]; p = 0.037), and physical activity (OR [95% CI] = 0.214 [0.07–0.68]; p = 0.010), while the factors associated with FMI were age (β [95% CI] = 0.30 [0.17–1.41]; p = 0.014), JADAS27 (β [95% CI] = 0.45 [0.16–1.08]; p = 0.009), and physical activity (β [95% CI] = −0.22 [−5.76 to 0.29]; p = 0.031). Conclusion: Our study revealed no differences between JIA patients with well‐controlled disease and low disability and the healthy population in BMI or body composition. Furthermore, the association observed between inflammatory activity and adiposity could be responsible for poorer clinical course.