Background/Purpose: Systemic JIA (sJIA) treatment has changed dramatically with the introduction of biologic agents, although treatment approaches may differ between countries. We characterized and compared presenting features and initial treatment of sJIA at pediatric rheumatology (PR) centers in the United States (US) and United Kingdom (UK).

Methods: The US data source was the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry, an observational registry established in 2010 that collects clinical data on children with incident or prevalent rheumatic disease from >55 clinical sites throughout the US. Children with sJIA who were enrolled in the Registry within 9 weeks of their first encounter with PR were included in the analysis of presenting features and children with clinical data available from 9 to 15 months following their first encounter with PR were included in the analysis of initial treatment. The UK data source was the Childhood Arthritis Prospective Study (CAPS), an observational study established in 2001 that collects clinical data at regular intervals from a cohort of children with newly diagnosed JIA from 7 UK PR centers. All children with sJIA were included in the analysis of presenting features and children with clinical data available from the 12 month visit were included in the analysis of initial treatment. We also evaluated a subset of CAPS children enrolled since 2009 to match the CARRA enrollment period. Presenting features and initial treatments were compared using chi-square, Fisher’s exact, and Wilcoxon ranksum tests.

Results: Presenting features are shown in Table 1 and medication use in the first 12 months is shown in Table 2. Disease manifestations were similar between the US and UK except hepatosplenomegaly was more frequent in the US (p=0.01). Elapsed time from first symptom to evaluation by PR was similar but slightly shorter in the US (p=0.01), and overall most children were evaluated within 2 months. Differences in enrollment procedures precluded valid comparisons of disease activity measures. US patients were more likely to receive biologic agents (specifically anakinra) and systemic glucocorticoids in the first 12 months of disease compared to UK patients.

Conclusion: Presenting features of children with sJIA were generally similar in the two countries. Compared to the UK, initial treatment of sJIA in the US more frequently included anakinra and, to a lesser extent, systemic glucocorticoids, which may represent differences in medication coverage.

Table 1. Presenting Features.

Table 2. Initial Medication Use in the First 12 Months of Disease