Juvenile Dermatomyositis in Afro-Caribbean children: a cohort study in the French West Indies.

INTRODUCTION: The epidemiology of Juvenile Dermatomyositis (JDM) in non-Caucasian population is poorly described. We performed a study of patients followed up in the French West Indies for JDM. We aimed to describe clinical and biological specificities during childhood.

METHODS: Retrospective study covering the period from Januarys 2000-2023. Listings of patients were obtained from multiple sources, namely computerized hospital archives, registry of referent pediatricians and adult specialists in internal medicine and the French National Registry for rare diseases. JDM and organ involvement were defined according to the international ILAR criteria.

RESULTS: Twenty-one patients were included over a 23 year-period. Median age at onset was 8.1 years (Range: 2.5-13.9) with a median follow up of 8 years (Range: 2-19). Two-thirds (14/21) had dysphagia at onset and 33% had respiratory involvement. Thirteen had specific autoantibodies (58%), most frequently anti-Mi-2. The median number of flares during childhood was three (1-9). During childhood, 76% had calcinosis lesions. Clinical evolution seemed to be more aggressive for boys than girls (respectively 4.2 versus 2.2 flares (p = 0.04) and 50% vs 18% needing more than one background therapy, p = 0.03).

CONCLUSION: This retrospective study is the largest cohort of pediatric patients of Afro-Caribbean and Black African descent treated for JDM in a high-income health system, and the first to describe the incidence and immunological profile in a population of African descent. They had higher rate of calcinosis and similar respiratory involvement. Overall outcomes during childhood were similar to North America and European countries.