History of infection before the onset of juvenile dermatomyositis: results from the National Institute of Arthritis and Musculoskeletal and Skin Diseases Research Registry.

OBJECTIVE: To obtain data concerning a history of infection occurring in the 3 months before recognition of the typical weakness and rash associated with juvenile dermatomyositis (JDM). METHODS: Parents or caretakers of children within 6 months of JDM diagnosis were interviewed by the registry study nurse concerning their child's symptoms, environment, family background, and illness history. Physician medical records were reviewed, confirming the JDM diagnosis. RESULTS: Children for which both a parent interview and physician medical records at diagnosis were available (n = 286) were included. Diagnoses were as follows: definite/probable JDM (n = 234, 82%), possible JDM (n = 43, 15%), or rash only (n = 9, 3%). The group was predominantly white (71%) and had a girl:boy ratio of 2:1. Although the mean age at onset was 6.7 years for girls and 7.3 years for boys, 25% of the children were < or =4 years old at disease onset. In the 3 months before onset, 57% of the children had respiratory complaints, 30% had gastrointestinal symptoms, and 63% of children with these symptoms of infection were given antibiotics. CONCLUSION: This study provides evidence that JDM affects young children. The symptoms of the typical rash and weakness often follow a history of respiratory or gastrointestinal complaints. These data suggest that the response to an infectious process may be implicated in JDM disease pathogenesis.

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.