Prediction of unfavorable outcome in Juvenile Idiopathic Arthritis (JIA) and assessment of the long-term outcomes in JIA-associated uveitis – A prospective Nordic multicenter study of JIA from childhood to adulthood

Abstract

Juvenile idiopathic arthritis (JIA) is a chronic childhood disease with joint inflammation as the main feature. The course and outcomes are heterogeneous with a large span in disease severity. There is increasing evidence that early aggressive treatment may modify the disease course in JIA. Precise determination of disease prognosis is therefore sought to guide early decisions on which children need disease modifying anti-rheumatic drugs (DMARDs) and biologics. We aimed to develop and validate clinically applicable models for the prediction of unfavorable outcomes in JIA. The goal was to improve JIA outcomes by providing a practical application to support clinicians in treatment decisions. We collaborated with Canadian researchers who separately had developed a model for predicting severe disease course. We developed a multivariable logistic regression model with eight clinical variables in the Nordic JIA cohort. The model performed well in predicting non-achievement of remission (the Nordic outcome), both in internal validation and in external validation in the Canadian cohort. We externally validated the Canadian model in the Nordic cohort yielding an excellent predictive ability. The Nordic model performed almost equally as well without blood tests and also performed well in predicting severe disease course (the Canadian outcome). The Canadian model did not attain an acceptable prediction of the Nordic outcome.

Uveitis is the most common extraarticular manifestation of JIA and may lead to severe sight-threatening complications. We found a high cumulative incidence of uveitis in 96 of 434 children (22%) in the Nordic cohort. Ocular complications, mainly cataract and glaucoma, were present in 39% of the young adults with uveitis at follow-up 18 years after onset of JIA. Predictors associated with development of ocular complications were uveitis before JIA, short interval between JIA and uveitis, and ANA positivity. Our results strongly suggest early and tight eye screening programs and close collaboration between ophthalmologists and pediatric rheumatologists for optimal treatment to minimize long-term complications.