The importance of small joint involvement in oligoarticular juvenile idiopathic arthritis.

Objectives: Our study aimed to evaluate the relationship of small joint involvement with demographic, clinical, and laboratory findings and to determine its possible effects on prognosis.

Methods: This retrospective observational study was conducted in patients diagnosed with oligoarticular juvenile idiopathic arthritis (oJIA) in the paediatric rheumatology department of Ankara City Hospital between April 2009 and September 2022. The relationship between small joint involvement and demographic, clinical, and laboratory findings and prognosis was investigated by statistical methods with the data recorded from the medical records of oJIA patients.

Results: Of the 198 patients diagnosed with oJIA, small joint involvement was observed in a total of 20 (10%) patients, 11 (5.5%) at the time of diagnosis, and 9 (4.5%) during the follow-up period. The frequency of small joint involvement in extended oJIA was significantly higher than in persistent oJIA (P = .001). Patients with small joint involvement had significantly higher erythrocyte sedimentation rate and C-reactive protein values at admission (P = .047, P = .038) and Juvenile Arthritis Disease Activity Score at 3, 6, and 12 months (P = .001, P = .001, P = .018). The need for conventional disease-modifying antirheumatic drugs and biologic disease-modifying antirheumatic drugs was significantly higher in patients with small joint involvement (P = .001, P = .001).

Conclusions: oJIA patients with small joint involvement may have higher acute phase reactants at diagnosis, a more extended course and active disease in follow-up, and the need for treatment escalation.