Predictors of disease course and remission in systemic juvenile idiopathic arthritis: significance of early clinical and laboratory features.

OBJECTIVE: To determine whether the disease course in systemic juvenile idiopathic arthritis (JIA) can be characterized as monophasic, polycyclic, or persistent, and to determine whether early clinical and laboratory characteristics can be used to predict the disease course and time to remission.
METHODS: Forty-five children with systemic JIA diagnosed between 1996 and 2000 were followed up with a standardized data collection protocol, including data on clinical and laboratory features (mean followup 4.9 years). Disease was considered inactive if the clinical and laboratory features were normal. Three definitions of remission were applied to classify disease course. Predictors of disease course were evaluated using multiple logistic regression. Predictors of time to remission were evaluated using Cox proportional hazards regression.
RESULTS: When applying a definition of remission requiring inactive disease while not receiving any medications for a period of 3 months, 42.2%, 6.7%, and 51.1% of the patients were classified as having monophasic, polycyclic, and persistent disease, respectively. Fever and active arthritis at 3 months (R2 = 0.42, area under the receiver operating characteristics curve [AUC] = 0.76) and an erythrocyte sedimentation rate (ESR) >26 mm/hour and corticosteroid use at 6 months (R2 = 0.49, AUC = 0.92) were predictive of a nonmonophasic course. Absence of active arthritis, an ESR of <26 mm/hour, and no requirement for corticosteroid therapy at 3 and 6 months were predictors of an earlier time to remission.
CONCLUSION: The disease course in systemic JIA can be characterized as monophasic, polycyclic, or persistent using a definition of remission requiring 3 months of inactive disease while not receiving any therapy. Features at 3 and 6 months are predictive of the disease course and time to remission.