title: Urban-rural differences in asthma prevalence among young people in Canada: the roles of health behaviors and obesity.
abstract: BACKGROUND
  Asthma prevalence has been reported to be lower in rural regions, but the reasons for this are not known.
  
  
  OBJECTIVE
  To confirm the existence of an urban-rural geographic gradient in asthma prevalence among Canadian youths and to evaluate whether this gradient was mediated by health behaviors.
  
  
  METHODS
  Cross-sectional data from 4,726 Canadian youth (grades 6-10) were collected during the 2001-02 Health Behaviour in School-Aged Children survey. Geographic region was categorized as metro (urbanized), non-metro but adjacent to metro, and rural. Asthma was defined via self-report of doctors' diagnoses and at least 1 of: (1) asthma symptoms or (2) a health care visit for asthma in the past year. Health behaviors (diet and physical activity) as well as obesity were also assessed.
  
  
  RESULTS
  Asthma prevalence was lowest in rural regions (metro = 17.7%, non-metro-adjacent = 15.6%, rural = 14.8%). A lower risk of asthma was associated with rural region (adjusted odds ratio [OR] = 0.76, 95% CI = 0.61-0.95) and living in non-metro-adjacent regions (adjusted OR = 0.81, 95% CI = 0.65-1.01). Health behaviors and obesity status did not mediate the association between geographic region and asthma. Being overweight or obese, having a high physical activity level, and exposure to passive smoking independently elevated the risk of asthma, whereas increased consumption of whole milk or vegetables were each protective.
  
  
  CONCLUSIONS
  Although asthma prevalence among youth was lower in rural areas, this association was not mediated by health behaviors or obesity. Other exposures, likely environmental, are the logical mechanisms through which rural geographic status is related to lower asthma prevalence.
authors.affiliation: Canadian Centre for Health and Safety in Agriculture, University of Saskatchewan, Saskatoon, SK, Canada. josh.lawson@usask.ca
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Lawson
authors.forename: Ian
authors.initials: I
authors.lastname: Janssen
authors.forename: Mark W
authors.initials: MW
authors.lastname: Bruner
authors.forename: Koroush
authors.initials: K
authors.lastname: Madani
authors.forename: William
authors.initials: W
authors.lastname: Pickett
mesh_terms: D000293:Adolescent; D000818:Animals; D001249:Asthma / Q000453:epidemiology*; D002170:Canada / Q000453:epidemiology; D002648:Child; D003430:Cross-Sectional Studies; D004032:Diet / Q000706:statistics & numerical data; D005260:Female; D015438:Health Behavior; D006306:Health Surveys; D006801:Humans; D008297:Male; D008892:Milk; D009043:Motor Activity; D009765:Obesity / Q000453:epidemiology*; D015995:Prevalence; D012423:Rural Health / Q000706:statistics & numerical data*; D014028:Tobacco Smoke Pollution / Q000706:statistics & numerical data; D014504:Urban Health / Q000706:statistics & numerical data*; D014675:Vegetables
chemical_list: D014028:Tobacco Smoke Pollution