Systemic juvenile idiopathic arthritis in French Afro-Caribbean children, a retrospective cohort study.

Introduction: The epidemiology and clinical presentation of systemic juvenile idiopathic arthritis (sJIA) in the Afro-Caribbean population is not well described.

Methods: Retrospective study conducted between January 2000 and January 2022 in the French Overseas Departments of America. Clinical data were obtained from multiple sources: computerized hospital archives, registries of referring pediatricians, and the French National Registry for rare diseases. The disease studied was sJIA defined according to international criteria.

Results: Twenty-five patients were identified. Mean age at diagnosis was 7.5 years (range: 1.2-14.9 years) and mean duration of follow-up was 5.2 years (range: 0.5-16 years). All patients had joint involvement at diagnosis with 68% presenting inflammatory arthritis and 32% inflammatory joint pain. Sixteen percent had coronary involvement at onset. More than half (52%) suffered from macrophage activation syndrome (MAS) during childhood (32% at onset). The mean number of flares in childhood was 2 (Range: 1-5). Sixty-eight percent of patients had disease control during childhood without biotherapy. The most frequent second line treatment was anakinra (7/8). There was no difference in clinical or biological severity according to gender. The median duration of treatment during childhood was 5 months (range: 2-144) and 72% had a cumulative treatment duration of less than one year.

Conclusion: These patients of Afro-Caribbean origin suffering from sJIA showed some specificities, such as a higher rate of MAS and coronary involvement at onset. The incidence per year was stable over a 20-year period. Overall outcomes during childhood were similar to western countries.