Systemic juvenile idiopathic arthritis: are there any predictors of disease course?

Abstract Background Systemic juvenile idiopathic arthritis (sJIA) is an autoinflammatory disorder with a variable disease course presenting either as monophasic or non-monophasic (polycyclic or persistent) course. Identifying clinical and laboratory features at presentation predicting these trajectories may guide early therapeutic decisions. This study aimed to evaluate predictors of disease course in children. Methods We conducted a retrospective observational study of children with sJIA over 18 years. Clinical features, laboratory parameters, treatment and disease outcomes were reviewed. Children with sJIA were classified as having monophasic, polycyclic or persistent disease based on clinical course. Logistic regression analysis, adjusted for age, gender, year of diagnosis, was performed to evaluate predictors of non-monophasic disease. Results Eighty children with sJIA were included, median age at diagnosis was 8 years (IQR 3.5-11) with median follow-up of 6 years (IQR 3-10). 34 (42.5%) monophasic, 8 (10%) polycyclic, and 38(47.5%) had persistent course. Rash (83.8%) followed by arthritis (66.3%) were most common presenting features, while macrophage activation syndrome (MAS) occurred in 18.8%. Polyarthritis at presentation was independently associated with non-monophasic disease (OR 12.68, 95% CI 2.69-59.90, p = 0.001). There was weak evidence to support an association between the clinical features and laboratory parameters, including MAS at presentation and disease trajectory. Conclusion sJIA is heterogenous and difficult to predict disease course at initial presentation. Polyarthritis identified children at high risk of a non-monophasic disease course in this study population. Early identification of these high-risk children may support timely escalation of targeted biologic therapy and improved long-term outcomes.