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

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 with sJIA.

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 and year of diagnosis, was performed to evaluate predictors of non-monophasic disease.

Eighty children with sJIA were included; median age at diagnosis was 8 years (interquartile range 3.5-11) with median follow-up of 6 years (interquartile range 3-10). Thirty-four (42.5%) were monophasic, 8 (10%) were polycyclic and 38 (47.5%) had a persistent course. Rash (83.8%) was the most common presenting feature, followed by arthritis (66.3%), while macrophage activation syndrome (MAS) occurred in 18.8%. Polyarthritis at presentation was independently associated with non-monophasic disease (odds ratio 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.

sJIA is heterogeneous and difficult to predict disease course at initial presentation. Polyarthritis at presentation was associated with increased 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.