Juvenile idiopathic arthritis in Southeast Asia: the Singapore experience over two decades

Objectives: To examine the clinical characteristics, treatment and outcomes of juvenile idiopathic arthritis (JIA) patients evaluated in Singapore and compare those with reports elsewhere.

Methods: Patients with JIA were recruited from our Singapore pediatric rheumatology registry from January 1997 to December 2015. Demographic, clinical, treatment, and outcome data were retrospectively collected. Nonparametric statistics were used to describe the data. Chi-squared, Mann-Whitney U, or Kruskal-Wallis tests were applied to compare differences between groups where appropriate. Multivariate logistic regression analyses were used to identify predictors for clinical parameters.

Results: Two hundred eighty-seven JIA patients with 60.6% males of predominantly Chinese descent were included in the study. The median onset age was 9 years (IQR 5.3-12.6), and the median follow-up duration was 30.1 months (IQR 9.1-61.7). Enthesitis-related arthritis (ERA, 32.8%) followed by persistent oligoarthritis (31.0%) was the most common. Elbow or ankle involvement predicted oligoarthritis extension (OR 15.8 (95% CI: 2.3-108.3, p = 0.005), 8.1 (95% CI: 1.5-45.3, p = 0.017)). JIA-associated uveitis was rare (2.8%) which paralleled the less common positive-ANA rate. Majority of our ERA patients had HLA-B27 (79.8%), together with older age predicted sacroiliitis (OR 4.7 (95% CI: 2.0-11.1, p < 0.05), OR 1.2 (95% CI: 1.1-1.3, p = 0.002)). TMJ involvement was under-reported. Methotrexate remained the most common DMARD used, but 36% of patients required biologics for which ERA and polyarthritis were the majority. Joint damage was rare.

Conclusion: This study highlights geographical and ethnic differences in JIA epidemiology. Compared with reports elsewhere, our JIA population had many unique findings and good functional outcomes requiring regional study validation. Key points • ERA is the most prominent JIA subtype in Singapore with high prevalence of HLA-B27. • JIA-associated uveitis is rare in SEA and is not associated with ANA or JIA-subtypes. • Elbow and/or ankle involvement at presentation is associated with oligoarthritis extension in our JIA cohort.