title: High risk of adult-onset asthma and work-related wheeze in farmers despite low prevalence of asthma in young farmers.
abstract: OBJECTIVE
  To investigate risk factors for asthma in farmers.
  
  
  METHODS
  A questionnaire was sent to all farms (n = 2499) and to 2900 controls aged 19-65 years from the general population in the county of Uppsala. Sixty per cent of the farms (1514 men and 248 women) and 64% of the controls (900 men, 943 women) responded.
  
  
  RESULTS
  Only 13% of the male farmers had heredity for allergy compared to 24% of the controls, and fewer farmers were smokers. After adjusting for confounders, male farmers had a significantly lower prevalence of doctor-diagnosed asthma and nocturnal breathlessness than the controls (OR 0.75, 95%CI 0.57-0.98 and OR 0.61, 95%CI 0.44-0.84), but a significantly higher prevalence of work-related wheeze (OR 1.74, 95%CI 1.30-2.35). The risk for asthma increased with age in the farmers. Of male farmers with asthma, 70% had developed asthma after the age of 21, in contrast with only 30% of the asthmatic controls. The young female farmers had a high prevalence of asthma.
  
  
  CONCLUSIONS
  Male farmers have an increased risk of work-related wheeze and adult-onset asthma increasing with age despite a lower prevalence of asthma during childhood and young age than in the general population.
authors.affiliation: Department of Medical Sciences, Occupational and Environmental Medicine, Uppsala University, Uppsala, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Lembke
authors.forename: C
authors.initials: C
authors.lastname: Janson
authors.forename: D
authors.initials: D
authors.lastname: Norbäck
authors.forename: A
authors.initials: A
authors.lastname: Rask-Andersen
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D000382:Agricultural Workers' Diseases / Q000453:epidemiology*; D001249:Asthma / Q000453:epidemiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012135:Respiratory Sounds / Q000209:etiology*; D012307:Risk Factors; D012737:Sex Factors; D011795:Surveys and Questionnaires; D013548:Sweden; D055815:Young Adult