The metabolic perspective in children with JIA

Introduction: Juvenile Idiopathic Arthritis (JIA) is the most common inflammatory chronic disease in childhood. According to International League of Association for Rheumatology (ILAR) seven subtypes of arthritis can be defined in relation with the number of joints and the extra-articular involvement occurring in the first six months of disease. Although it has been largely recognized that these patients are at risk for disease-specific complications and for metabolic syndrome (MetS) in adulthood, very limited data are available on metabolic risk at this age. Robust evidence demonstrates that high acid uric (UA) levels represent a risk factor for cardiometabolic diseases such as MetS, cardiovascular disease, and type 2 diabetes in adults. In children, serum UA levels increased in youth with obesity and metabolic abnormalities. Objectives: To investigate the metabolic risk in children with JIA. Methods: We retrospectively evaluated 113 children affected by JIA classified according to ILAR criteria attending our Rheumatology Clinic. Both clinical and biochemical assessments were performed. Participants were stratified in four groups according to sex-specific quartiles of UA. Disease activity was calculated by Juvenile Arthritis Disease Activity Score 10 (JADAS-10). Differences for continuous variables were analysed with the independent-sample t test for normally distributed variables and with the Mann-Whitney test in case of non-normality. Qualitative variables were compared using the chi-squared test. Results: The mean age of our cohort was 7.43±4.03 years. Systolic blood pressure levels and BMI-Z score significantly increased across quartiles (p= 0.002 and p=0.003, respectively). Patients belonging to the highest UA quartile also showed higher triglycerides and total cholesterol (p=0.01 and p=0.025, respectively) and lower HDL cholesterol levels (p<0.0001) than subjects belonging to the lowest quartiles. JADAS-10 score, ferritin and erythrocyte sedimentation rate levels, and age at disease onset did not significantly differ across UA quartiles (all p >0.05), but a trend for JADAS-10 score was observed (p=0.06). With regard to treatment, the prevalence of the use of biological drugs significantly increased across UA quartiles (p=0.04). Conclusion: A worse cardiometabolic profile across UA quartiles has been observed in children with JIA. Our preliminary data suggest that in clinical practice UA might represent a useful marker of cardiometabolic risk in children with JIA. Taking into account the increased MetS development risk later in life in these patients, a careful global management is highly recommended, by paying attention not only to disease-specific comorbidities (e.g. uveitis, etc) but also to both metabolic and cardiovascular derangements at an earlier stage of JIA. Further studies are needed to better clarify the early cardiometabolic risk in JIA patients and its potential influence on treatment response.