The Systemic Juvenile Idiopathic Arthritis Cohort of the Childhood Arthritis and Rheumatology Research Alliance Registry: 2010-2013.

We aimed to identify the (1) demographic/clinical characteristics, (2) medication usage trends, (3) variables associated with worse disease activity, and (4) characteristics of patients with persistent chronic arthritis in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Legacy Registry's systemic juvenile idiopathic arthritis (sJIA) cohort.

Demographics, disease activity measures, and medications at enrollment of patients with sJIA in the CARRA Registry were analyzed using descriptive statistics. Multivariate analyses were conducted to identify associations with increased disease activity. Medication usage frequencies were calculated by year.

There were 528 patients with sJIA enrolled in the registry (2010-2013). There were 435 patients who had a complete dataset; of these, 372 met the International League of Associations for Rheumatology criteria and were included in the analysis. At enrollment, median disease duration and joint count were 3.7 years and 0, respectively; 16.4% had a rash and 6.7% had a fever. Twenty-six percent were taking interleukin 1 (IL-1) inhibitors and 29% glucocorticoids. Disease-modifying antirheumatic drugs and tumor necrosis factor inhibitors use decreased, while IL-6 inhibitor use increased between 2010 and 2013. African American patients had worse joint counts (p = 0.003), functional status (p = 0.01), and physician's global assessment (p = 0.008). Of the 255 subjects with > 2 years of disease duration, 56% had no arthritis or systemic symptoms, while 32% had persistent arthritis only.

Most patients in the largest sJIA cohort reported to date had low disease activity. Practice patterns for choice of biologic agents appeared to change over the study period. Nearly one-third had persistent arthritis without systemic symptoms > 2 years after onset. African Americans were associated with worse disease activity. Strategies are needed to improve outcomes in subgroups with poor prognosis.