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 child ren 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 Walto n 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 diag nosis 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 destruc tive arthritis in children with systemic-onset JRA, the patients were class ified 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 d isease (persistent fever or corticosteroid requirement for control of syste mic disease) and a platelet count greater than or equal to 600 x 10(9)/lite r. Poor outcome was defined as moderate or severe disability (defined as a score of greater than or equal to0.75 on the Childhood Health Assessment Qu estionnaire) 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 yea rs (SD 3.7), The mean age at outcome assessment was 13.5 years (SD 5.3), Th ere were 51 boys and 60 girls. Twenty-four patients (22%) had moderate-to-s evere disability and 2 patients died; these 26 patients were considered to have had a poor outcome. We could determine risk classification for 104 pat ients. Twenty-four patients (23%) met the criteria for high risk at the 6-m onth visit. Overall, the risk of a poor functional outcome was significantl y 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 w ith >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 charact erized by fever or the need for corticosteroids, and thrombocytosis strongl y predicted the development of a poor functional outcome in these patients. This was especially apparent with longterm followup. Our study validates t he previously developed prognostic criteria for systemic-onset JRA.