Environmental factors preceding illness onset differ in phenotypes of the juvenile idiopathic inflammatory myopathies

Rheumatology (Oxford). 2010 Dec;49(12):2381-90. doi: 10.1093/rheumatology/keq277. Epub 2010 Aug 27.


Objective: To assess whether certain environmental factors temporally associated with the onset of juvenile idiopathic inflammatory myopathies (JIIMs) differ between phenotypes.

Methods: Physicians completed questionnaires regarding documented infections, medications, immunizations and an open-ended question about other noted exposures within 6 months before illness onset for 285 patients with probable or definite JIIM. Medical records were reviewed for 81% of the patients. Phenotypes were defined by standard clinical and laboratory measures.

Results: Sixty per cent of JIIM patients had a reported exposure within 6 months before illness onset. Most patients (62%) had one recorded exposure, 26% had two and 12% had three to five exposures. Patients older than the median age at diagnosis, those with a longer delay to diagnosis and those with anti-signal recognition particle autoantibodies had a higher frequency of documented exposures [odds ratios (ORs) 95% CI 3.4, 31]. Infections were the most common exposure and represented 44% of the total number of reported exposures. Non-infectious exposures included medications (18%), immunizations (11%), stressful life events (11%) and unusual sun exposure (7%). Exposures varied by age at diagnosis, race, disease course and the presence of certain myositis autoantibodies.

Conclusion: The JIIMs may be related to multiple exposures and these appear to vary among phenotypes.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age of Onset
  • Autoantibodies / genetics*
  • Child, Preschool
  • Environmental Exposure / adverse effects*
  • Female
  • Genetic Predisposition to Disease / genetics*
  • Humans
  • Male
  • Myositis / diagnosis*
  • Phenotype
  • Risk Factors
  • Time Factors


  • Autoantibodies