US incidence of juvenile dermatomyositis, 1995-1998: results from the National Institute of Arthritis and Musculoskeletal and Skin Diseases Registry.

OBJECTIVE: To estimate the incidence of juvenile dermatomyositis (juvenile DM) in the United States between 1995 and 1998.

METHODS: Physician referrals to the National Institute of Arthritis and Musculoskeletal and Skin Diseases Juvenile Dermatomyositis Research Registry and the National Pediatric Rheumatology Disease Registry from Indiana University were utilized for a 2-source capture-recapture estimation of Juvenile DM annual incidence.

RESULTS: For children 2-17 years of age, the estimated annual incidence rates from 1995 to 1998 in the US ranged from 2.5 to 4.1 juvenile DM cases per million children, and the 4-year average annual rate was 3.2 per million children (95% confidence interval 2.9-3.4). Estimated annual incidence rates by race were 3.4 for white non-Hispanics, 3.3 for African American non-Hispanics, and 2.7 for Hispanics. During the 4-year period of the study, completeness of ascertainment for the combined registries ranged from 56% to 86% and girls were affected more than boys (ratio 2.3:1).

CONCLUSION: This study provides evidence for sex, and possibly racial differences in the risk of juvenile DM in the US.