title: Prevalence of peanut allergy in primary-school children in Montreal, Canada.
abstract: BACKGROUND
  Peanut allergy is receiving increasing attention. Only one study has estimated the prevalence in North America, but it did not corroborate history with diagnostic testing.
  
  
  OBJECTIVE
  We estimated the prevalence of peanut allergy in Montreal by administering questionnaires regarding peanut ingestion to children in kindergarten through grade 3 in randomly selected schools.
  
  
  METHODS
  Respondents were stratified as follows: (1). peanut tolerant, (2). never-rarely ingest peanut, (3). convincing history of peanut allergy, and (4). uncertain history of peanut allergy. Groups 2, 3, and 4 underwent peanut skin prick tests (SPTs), and if the responses were positive in groups 2 or 4, measurement of peanut-specific IgE were undertaken. Children in group 3 with a positive SPT response were considered allergic to peanut without further testing. Children in groups 2 and 4 with peanut-specific IgE levels of less than 15 kU/L underwent oral peanut challenges.
  
  
  RESULTS
  Of the 7768 children surveyed, 4339 responded, 94.6% in group 1. The prevalence of peanut allergy was 1.50% (95% CI, 1.16%-1.92%). When multiple imputation was used to incorporate data on those responding to the questionnaire but withdrawing before testing, the estimated prevalence increased to 1.76% (95% CI, 1.38%-2.21%). When data regarding the peanut allergy status of nonresponders (as declared to the school before the study) were also incorporated, the estimated prevalence was 1.34% (95% CI, 1.08%-1.64%).
  
  
  CONCLUSIONS
  Our prevalence study is the first in North America to corroborate history with confirmatory testing and the largest worldwide to incorporate these techniques. We have shown that, even with conservative assumptions, prevalence exceeds 1.0%.
authors.affiliation: Department of Pediatrics, McGill University Health Care Centre, Montreal, Quebec, Canada.
authors.forename: Rhoda S
authors.initials: RS
authors.lastname: Kagan
authors.forename: Lawrence
authors.initials: L
authors.lastname: Joseph
authors.forename: Claire
authors.initials: C
authors.lastname: Dufresne
authors.forename: Katherine
authors.initials: K
authors.lastname: Gray-Donald
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Turnbull
authors.forename: Yvan St
authors.initials: YS
authors.lastname: Pierre
authors.forename: Ann E
authors.initials: AE
authors.lastname: Clarke
mesh_terms: D010367:Arachis / Q000276:immunology; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D021183:Peanut Hypersensitivity / Q000453:epidemiology*; D015995:Prevalence; D012574:Schools; D012882:Skin Tests; D011795:Surveys and Questionnaires
chemical_list: D007073:Immunoglobulin E