Early predictors of poor functional outcome in systemic‐onset juvenile rheumatoid arthritis: A multicenter cohort study

Objective To examine the ability of a previously described set of criteria to predict poor functional outcome in a large, multicenter cohort of children with systemic‐onset juvenile rheumatoid arthritis (JRA). Methods All children who were diagnosed with systemic‐onset JRA since 1980 at the Hospital for Sick Children (Toronto), since 1983 at the Isaac Walton Killam Hospital for Children (Halifax), and since 1981 at the Children's Hospital of Eastern Ontario (Ottawa) were evaluated. Patients were included in the study if they had been evaluated clinically within 6 months of diagnosis and had been followed up for at least 2 years. Patients were divided into 4 cohorts according to their length of followup: 2–4 years, 4–7 years, 7–10 years, and >10 years. Using previously described criteria for destructive arthritis in children with systemic‐onset JRA, the patients were classified as either high risk or low risk for poor functional outcome based on the data from their 6‐month visit. High‐risk patients had active systemic disease (persistent fever or corticosteroid requirement for control of systemic disease) and a platelet count ≥600 × 10 9 /liter. Poor outcome was defined as moderate or severe disability (defined as a score of ≥0.75 on the Childhood Health Assessment Questionnaire) or disease‐associated death. Results Among 122 eligible patients with systemic‐onset JRA, we were able to contact 111 (91%) for outcome data. The mean followup period was 7.7 years (SD 3.7). The mean age at outcome assessment was 13.5 years (SD 5.3). There were 51 boys and 60 girls. Twenty‐four patients (22%) had moderate‐to‐severe disability and 2 patients died; these 26 patients were considered to have had a poor outcome. We could determine risk classification for 104 patients. Twenty‐four patients (23%) met the criteria for high risk at the 6‐month visit. Overall, the risk of a poor functional outcome was significantly higher in the high‐risk group (relative risk 3.3, 95% confidence interval [95% CI] 1.73–6.43, P = 0.0004). This risk was most marked in the cohort with >10 years of followup (relative risk 4.3, 95% CI 1.82–10.29, P = 0.006). Conclusion The presence of active systemic disease at 6 months, as characterized by fever or the need for corticosteroids, and thrombocytosis strongly predicted the development of a poor functional outcome in these patients. This was especially apparent with long‐term followup. Our study validates the previously developed prognostic criteria for systemic‐onset JRA.