Factors associated with poor prognosis of hip arthritis in juvenile idiopathic arthritis: Data from the JIR cohort.

OBJECTIVES:Hip involvement remains a predictor of severe juvenile idiopathic arthritis (JIA) course and carries a high risk of disability. This study aims to determine the factors of poor prognosis of hip involvement in patients with JIA and to assess the treatment response. METHODS:This is a multicenter observational cohort study. Patients were selected from the JIR Cohort database. Hip involvement was defined as clinically suspected and confirmed by an imaging tool. Follow-up data were collected during 5 years. RESULTS:Among the 2223 patients with JIA, 341(15%) patients had hip arthritis. Male gender, enthesitis-related arthritis, and North African origin were factors associated with hip arthritis. Hip inflammation was associated with disease activity parameters during the first year, particularly Physician Global Assessment, joint count, and inflammatory marks. Structural hip progression was associated with early onset of the disease, a longer time to diagnosis, geographic origin, and JIA subtypes. Anti-TNF therapy was found to be the only treatment able to effectively reduce structural damage progression. CONCLUSION:The early onset diagnostic delay, origin, and systemic subtype of JIA predict a poor prognosis of hip arthritis in children with JIA. The use of anti-TNF was associated with a better structural prognosis.