Phenotypic characteristics and outcome of juvenile dermatomyositis in Arab children.

This study describes the disease characteristics and outcome of Arab children with juvenile dermatomyositis (JDM) and compares the findings with other ethnicities. We retrospectively reviewed the hospital registries of the participating hospitals for children with JDM seen between 1990 and 2016 in three Arab countries. All patients fulfilled Bohan and Peter criteria for JDM, diagnosed before 14 years of age and were of Arab ethnicity. Clinical and laboratory features as well as the long-term outcomes including accrual disease damage were collected at the last follow-up visit. A total of 92 JDM patients (58 girls) were included. Mean age at the onset was 6 ± 3 years, with a mean follow-up duration of 5 ± 4.4 years. Forty-three patients (46.7%) had polycyclic disease course, 34 (36.9%) had a monocyclic course, while 15 (16.3%) had a continuous progressive course. Forty-five patients (48.9%) had arthritis, 14 (15.2%) patients had an upper airway and dysphagia, and 10 patients (10.9%) had lung involvement. Eight patients (8.7%) were admitted to the intensive care unit (ICU), 4 of them required mechanical ventilation. Methotrexate had been the most frequently used immunosuppressive drug (86%) and rituximab was used in eight patients. Additionally, 31 patients received IVIG. Most of the patients achieved a complete clinical response, but 16 ended up with permanent skin changes and 12 had a residual muscle weakness. Twenty-seven patients developed calcinosis. There were two deaths due to infection during the follow-up period. We report the largest phenotypic data on Arab children with JDM. Our patients have similar characteristics to previously described cohorts. Majority of the patients remained with inactive disease.