Radiologic features in juvenile idiopathic arthritis: A first step in the development of a standardized assessment method

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Abstract
Objective To describe radiologic features of patients with juvenile idiopathic arthritis (JIA) in a standardized manner, to test the reliability and feasibility of this description, and to correlate these features with clinical signs as a first step in the development of a standardized assessment method. Methods The placebo‐controlled study of sulfasalazine in patients with oligoarticular, extended oligoarticular, and polyarticular JIA performed by the Dutch Juvenile Idiopathic Arthritis Study Group yielded the data for this study. All trial entry radiographs (clinically involved joints and contralateral joints) were scored (in consensus by a skeletal radiologist and pediatric rheumatologist) for the presence of swelling, osteopenia, joint space narrowing, growth abnormalities, subchondral bone cysts, erosions, and malalignment. Results Data on 67 of 69 patients were analyzed. The mean age was 9.1 years (range 2.5–17.6 years), and the median disease duration was 24 months (range 5–176 months). Thirteen percent of the patients were IgM rheumatoid factor (IgM‐RF) positive, and 16% were HLA–B27 positive. All 68 clinically evaluated joints were included in the maximum of 19 radiographed joints (or joint groups) per patient. The mean number of radiographed joints per patient was 7 (range 2–15); knees, hands, ankles, and feet were most frequently affected. Fifty‐eight patients (87%) had radiologic abnormalities in at least one joint (soft‐tissue swelling in 63% of patients, growth disturbances in 48%, joint space narrowing in 28%, and erosions in 15%). In total, half of the radiographs of the clinically involved joints showed radiologic abnormalities, including two‐thirds of the radiographs of the clinically affected hands and knees. Univariate analysis revealed a good correlation between the overall articular (clinical) severity and the presence of radiologic abnormalities (odds ratio [OR] 1.38, P < 0.0001). Multivariate analysis showed increased ORs for the presence of radiologic abnormalities and IgM‐RF positivity (OR 4.6, P = 0.005) or HLA–B27 positivity (OR 3.0, P = 0.004). In general, reproducibility of the radiologic scoring method was good (mean kappa coefficient of 0.74 [range 0.40–0.86]), although there were scoring discrepancies for swelling, osteopenia, and growth disturbances. The scoring took 10–20 minutes per patient. Conclusion Our model of describing and scoring radiologic abnormalities of radiographed joints in JIA was feasible, mostly reproducible, correlated well with the overall articular severity score, and added substantial new information not available on clinical examination.