title: Epidemiology of juvenile idiopathic arthritis in a multiethnic cohort: ethnicity as a risk factor.
abstract: OBJECTIVE
  To study the influence of ethnicity on the risk of developing juvenile idiopathic arthritis (JIA) in a multiethnic community of patients with unrestricted access to health care.
  
  
  METHODS
  A questionnaire on ethnicity was distributed to all patients with JIA being followed up at the Hospital for Sick Children in Toronto, Ontario, Canada. Of 1,082 patients, 859 (79.4%) responded to the questionnaire. To calculate the relative risk (RR) of developing JIA in this study cohort, the results were compared with data from the age-matched general population of the Toronto metropolitan area (TMA) as provided in the 2001 census from Statistics Canada.
  
  
  RESULTS
  European descent was reported by 69.7% of the patients with JIA compared with a frequency of 54.7% in the TMA general population, whereas a statistically significantly lower than expected percentage of the patients with JIA reported having black, Asian, or Indian subcontinent origin. Children of European origin had a higher RR for developing any of the JIA subtypes except polyarticular rheumatoid factor (RF)-positive JIA, and were particularly more likely to develop the extended oligoarticular and psoriatic subtypes. A higher frequency of enthesitis-related JIA was observed among patients of Asian origin, while those of black origin or native North American origin were more likely to develop polyarticular RF-positive JIA.
  
  
  CONCLUSIONS
  In this multiethnic cohort, European descent was associated with a significantly increased risk of developing JIA, and the distribution of JIA subtypes differed significantly across ethnic groups.
authors.affiliation: Zurich University Children's Hospital, Zurich, Switzerland. traudel.saurenmann@kispi.unizh.ch
authors.forename: R K
authors.initials: RK
authors.lastname: Saurenmann
authors.forename: J B
authors.initials: JB
authors.lastname: Rose
authors.forename: P
authors.initials: P
authors.lastname: Tyrrell
authors.forename: B M
authors.initials: BM
authors.lastname: Feldman
authors.forename: R M
authors.initials: RM
authors.lastname: Laxer
authors.forename: R
authors.initials: R
authors.lastname: Schneider
authors.forename: E D
authors.initials: ED
authors.lastname: Silverman
mesh_terms: D000293:Adolescent; D000974:Antibodies, Antinuclear / Q000378:metabolism; D001171:Arthritis, Juvenile / Q000453:epidemiology / Q000208:ethnology*; D044466:Asian People / Q000208:ethnology; D044383:Black People / Q000208:ethnology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D007223:Infant; D008297:Male; D009864:Ontario / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D014605:Uveitis / Q000453:epidemiology / Q000208:ethnology; D044465:White People / Q000208:ethnology*
chemical_list: D000974:Antibodies, Antinuclear