title: Childhood asthma in four countries: a comparative survey.
abstract: BACKGROUND
  Asthma mortality among young people varies widely between different countries. Geographical differences in asthma prevalence are also believed to exist, but evidence is sparse owing to the lack of multicentre surveys using common protocols. A survey was conducted of 12-year-old children living in defined areas of New Zealand, Wales, South Africa and Sweden, in order to see whether asthma prevalence and mortality rates in children show parallel differences.
  
  
  METHODS
  Questionnaires enquiring about a history of asthma and respiratory symptoms were issued to the parent. The children performed a simple exercise challenge test.
  
  
  RESULTS
  Information was obtained for 4353 children. A history of asthma at any time was reported for 16.8% of children in New Zealand, 12.0% in Wales, 11.5% in South Africa and 4.0% of Sweden, and a similar pattern was shown by several other indices of asthma (various relevant symptoms, inhaler use, response to exercise challenge, and asthma mortality at ages 5-19 years). In Sweden wheezing was negatively associated with pet ownership; elsewhere there was a positive (though non-significant) association. Cat ownership was highest in New Zealand and lowest in Sweden.
  
  
  CONCLUSIONS
  The prevalence of asthma in children shows geographical variation which is parallel to that of asthma mortality, being high in New Zealand and low in Sweden. Differential exposure to animal allergens is a possible factor in this variation.
authors.affiliation: University of Wales College of Medicine, Centre for Applied Public Health Medicine, Cathays Park, Cardiff, UK.
authors.forename: M L
authors.initials: ML
authors.lastname: Burr
authors.forename: E S
authors.initials: ES
authors.lastname: Limb
authors.forename: S
authors.initials: S
authors.lastname: Andrae
authors.forename: D M
authors.initials: DM
authors.lastname: Barry
authors.forename: F
authors.initials: F
authors.lastname: Nagel
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000208:ethnology / Q000209:etiology / Q000401:mortality*; D002423:Cause of Death; D002648:Child; D002675:Child, Preschool; D003431:Cross-Cultural Comparison; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D013019:South Africa / Q000453:epidemiology; D013548:Sweden / Q000453:epidemiology; D014852:Wales / Q000453:epidemiology