Clinical Profile of Polyarticular Juvenile Idiopathic Arthritis on Short-Term and Medium-Term Follow-up in a Tertiary Care Centre

Background: Polyarticular juvenile idiopathic arthritis (polyJIA) is a chronic inflammatory arthritis involving five or more joints and may result in persistent disease, joint deformity, and functional impairment. Data regarding its clinical profile and follow-up outcomes among Indian children remain limited. The objective is to evaluate the clinical and laboratory profile of children with polyarticular JIA and assess short-term and medium-term outcomes in terms of joint involvement, treatment response, and disease activity. Material and Methods: This hospital-based retrospective and prospective observational study included 184 children with polyarticular JIA attending the Indira Gandhi Institute of Child Health, Bengaluru, from August 2022 to February 2024. Demographic characteristics, clinical manifestations, joint involvement, laboratory parameters, RF and ANA status, and treatment were documented. Patients were assessed at approximately six months and one year for clinical symptoms, joint involvement, laboratory parameters, treatment response, and disease outcome. Results: Of 184 children, 145 (78.8%) were females and 39 (21.2%) were males, with a male-to-female ratio of 1:3.72. The mean age at disease onset was 7.2 ± 4.3 years. Joint pain (97.8%), joint swelling (59.2%), and morning stiffness (56.5%) were common manifestations. The knee was most frequently involved (72.8%), followed by the wrist (66.8%) and ankle (64.7%). Anaemia was present in 65.2%, while ESR was elevated in 77.1%. RF and ANA positivity were observed in 25.0% and 13.6%, respectively, among the overall cohort. The median total number of involved joints decreased from 13 at baseline to 6 at six months and 2 at one year. Inactive disease increased from 3.8% at six months to 23.9% at one year. RF-positive patients had a significantly later age at onset (8.3 vs 6.7 years; p=0.03) and a greater proportion with active disease during follow-up (87.0% vs 60.2%; p=0.03). Conclusion: Polyarticular JIA predominantly affected females and commonly involved the knee, wrist, and ankle joints. Progressive improvement in clinical manifestations, joint involvement, and inflammatory activity was observed during follow-up. However, persistent active disease, particularly among RF-positive patients, highlights the importance of early treatment and continued disease monitoring.

Keywords: Polyarticular juvenile idiopathic arthritis; JIA; rheumatoid factor; antinuclear antibody; methotrexate; biologics; disease activity; remission.