The purpose of this study was to identify demographic and clinical characteristics, onset season, and interval between disease index date and diagnosis/therapy in 80 children with new onset juvenile dermatomyositis(JDMS) and to evaluate the relationship of socioeconomic status to these factors. Families of JDMS children in a cohort, within 6 months of diagnosis, who met criteria, had a strctured interview. All the children had rash (100%) and proximal muscle weakness (100%); 59 (74%) had muscle pain; 52 (65%) fever; 36 (45%) dysphagia; 35 (44%) hoarseness; 30 (38%); abdominal pain; 29 (36%) arthritis; 18 (23%) calcinosis, and 11 (14%) melena. Muscle derived enzymes were normal in 10% of children; 18% had a normal EMG and muscle biopsy was normal or nondiagnositic in 19%. Median time from disease index date to diagnosis was different between racial groups: Caucasians (n=59)--2.0 months; for minorities (n=21)--7.0 months, (p=.0007). The median time from disease index date to therapy initiation was also different between racial groups: for Caucasians, 3.0 months, and for minorities, 7.4 months, (p=.0009). 94% of the children took steroids and 7% received methotrexate at the time of interview. For JDMS with disease index dates in Summer (41%, n=33), rash preceded muscle weakness in 80% (n=27). Conclusion: The increased occurrence of the JDMS rash in Summer suggests that the sun is a factor in disease pathogenesis. Minority children have a longer time interval between diagnosis and initiation of therapy.

Supported by a Clinical Science Grant from The Arthritis Foundation.