There are no validated criteria to evaluate clinical response in juvenile idiopathic arthritis (JIA). The purpose of this study was to compare 4 sets of criteria (2 from the American College of Rheumatology [ACR] and 2 from the European League Against Rheumatism [EULAR]) for clinical response evaluation in JIA patients treated with methotrexate and/or anti-tumor necrosis factor alpha drugs.
Seventy-five patients with JIA were evaluated at baseline and after 6 months of therapy with second-line drugs. Mean age at study onset was 12.8 years (range 2-32.9 years). Diagnoses were systemic JIA (n = 16), rheumatoid factor-positive JIA (n = 5), rheumatoid factor-negative JIA (n = 9), persistent oligoarticular JIA (n = 10), extended oligoarticular JIA (n = 33), and psoriatic arthritis (n = 2). Clinical response was evaluated with the ACR Pediatric 30 criteria and the ACR 20% response criteria (ACR20), and with the EULAR Disease Activity Score (DAS) and 28-joint DAS (DAS28). Patients with EULAR criteria responses of "good" or "moderate" were classified as responders. Responders and nonresponders according to the different criteria were then compared.
For patients younger than 16 years, Cohen's kappa varied between 0.51 and 0.72, with a good-to-excellent reproducibility index for all comparisons, except for the DAS28/ACR20 comparison. The best agreement was obtained by comparing the DAS and the ACR Pediatric 30. For patients older than 16 years, the reproducibility index was good or excellent in only 2 cases, i.e., comparing the DAS and the ACR Pediatric 30 and comparing the DAS and the DAS28 (as expected).
Our study shows a good agreement overall for the different criteria tested. The highest concordance was observed between the DAS and the ACR Pediatric 30, the lowest between the DAS28 and the ACR20. Our data suggest that the ACR Pediatric 30 criteria can be used also in adult patients affected by JIA, and that the original DAS can be an alternative to the ACR Pediatric 30 in both children and young adults with JIA.