Clinical Course and Prognostic Value of Disease Activity in the First Two Years in Different Subtypes of Juvenile Idiopathic Arthritis

Objective. Juvenile idiopathic arthritis (JIA) is a heterogeneous disease involving chronic arthritis. The clinical course is characterized by a fluctuating pattern of active and inactive disease. We have described in detail the clinical course in different JIA subtypes during the first 2 years after diagnosis and studied its relationship to disease activity in the following years. Methods. Detailed clinical data on different parameters describing the disease activity in sequential time periods covering the first 2 years after diagnosis were retrieved from the charts of 311 patients with JIA and compared between subtypes. In a cohort of 146 patients, the relation of these different clinical variables to the course of disease in the following 3 years was evaluated. Results. The percentage of time with active disease in the first 2 years differed significantly between subtypes. In all subtypes, a broad spectrum of activity was observed. The time with active disease in the first 2 years was the most significant factor associated with the duration of active disease in the following years. Conclusion. Different percentages of time with active disease have been observed between JIA subtypes in the first 2 years. The cumulative duration of activity varied widely within each subtype. Regarding the prognosis of the individual patient, the clinical course in the first 2 years appears to be predictive of the clinical course in the following years. Patients that have less time with active disease in the first 2 years are not likely to develop an unremitting clinical course later on.