Analysis of disease activity, functional disability and articular damage in patients with juvenile idiopathic arthritis: a prospective outcome study.

OBJECTIVES: We longitudinally studied outcomes of patients with juvenile idiopathic arthritis (JIA) using the Childhood Health Assessment Questionnaire (CHAQ) for physical disability and the Juvenile Arthritis Damage Index for articular (JADI-A) and extra-articular damage (JADI-E), and we correlated them with various disease activity variables.
METHODS: Eighty-seven patients with JIA were included in the prospective follow-up study with median age 14 years (4.6-18.0), disease duration 5.2 years (2.0-18.9) and follow-up of 4.0 years (2.0-5.2). Besides JADI-A and JADI-E, and the assessment of active joints count, joints with limited mobility, ESR, CHAQ and radiographic damage of joints was also done. A correlation analysis of CHAQ and JADI with various disease activity variables was performed.
RESULTS: The patient's distribution of JIA subtypes were polyarticular (32), systemic onset (13), oligoarticular (31), and enthesitis related arthritis (11). After a follow-up period, 46% patients had active disease compared to 83% patients at baseline (p<0.01). The CHAQ disability index improved over baseline, while radiological damage (p<0.001) and JADI-A and JADI-E scores worsened (p<0.001). CHAQ and JADI significantly correlated with the majority of disease activity variables. CHAQ DI was significantly higher in the patients with coxitis (p<0.01) and wrist arthritis (p<0.001). The most pronounced deterioration in articular damage (JADI-A) was observed in patients with sJIA (3.69 at baseline vs. 5.69 at study endpoint).
CONCLUSIONS: The improvement of functional disability (CHAQ DI) was observed over the course of the disease, whereas radiological joint damage, JADI-A and JADI-E scores worsened. Children with systemic JIA, wrist arthritis, coxitis and prolonged active disease are at higher risk of progression of severe disability.