Determinants of asthma in a farming population

Scand J Work Environ Health. 1998 Aug;24(4):262-9. doi: 10.5271/sjweh.319.


Objectives: This study examined the determinants of asthma in a population of farmers, including as a crude indicator of genetic predisposition "history of asthma in next-of-kin" (family history), and exposure factors such as animal production and smoking.

Methods: In a cross-sectional study of 8482 farmers or farmers' spouses in Norway a questionnaire with information on asthma among the subjects and their next-of-kin, production type and farming activities, exposures outside farming, and smoking was applied. Spirometry was performed.

Results: The lifetime prevalence of self-reported asthma in the population was 6.3%. Significant risk factors for current asthma were asthma among next-of-kin, asthma as child or adolescent, animal production, and age. In a comparison with subjects with no family history of asthma and no animal production the adjusted odds ratio for current asthma in never smokers was 1.9 [95% confidence interval (95% CI) 0.4-8.9] for subjects with family history only, 2.2 (95% CI 1.1-4.2) for subjects with animal production only, and 6.3 (95% CI 3.1-13.1) for subjects with both factors. A combination of animal production, smoking, and a positive family history gave an odds ratio of 8.1 (95% CI 4.0-16.2) for current asthma.

Conclusions: The study can be interpreted as support for the hypothesis of an interaction between genetic factors and exposure factors in the causation of asthma. Since familial associations may be exposure-related, the necessity of considering indicators of both inheritance and exposure in epidemiologic studies of asthma is emphasized.

MeSH terms

  • Adult
  • Aged
  • Agricultural Workers' Diseases / etiology*
  • Animal Husbandry
  • Animals
  • Asthma / etiology*
  • Asthma / genetics
  • Female
  • Genetic Predisposition to Disease / genetics
  • Humans
  • Male
  • Middle Aged
  • Norway
  • Occupational Exposure / adverse effects*
  • Risk Factors
  • Smoking / adverse effects
  • Spirometry