Prevalence and risk factors of chronic obstructive pulmonary disease in dairy farmers: AIRBAg study

Background: The AIRBAg study was designed to assess the prevalence of chronic obstructive pulmonary disease (COPD) in dairy farmers and to define its associated risk factors.

Methods: Between March 2012 and February 2017 randomly selected dairy farmers in the French region of Brittany were asked to complete a self-administered questionnaire and undergo an occupational health check-up with electronic mini-spirometry and standard spirometry. Those having one or more of the following features: chronic cough, chronic bronchitis, wheezing, dyspnea and/or a ratio FEV₁/FEV₆ < 80% were then referred to a pulmonologist for further check-up including spirometry with a reversibility test. Each COPD case was matched with three controls (dairy farmers and non-farm employees), for sex and age ( ± 5 years). Conditional multivariate logistic regression models were used to estimate the odds ratios between COPD occurrence and various risk factors.

Results: The 1203 farmers examined included 525 (43.6%) who were "at risk of bronchial obstruction" and 432 (35.9%) of these saw the pulmonologist. This screening identified 16 (1.3%) cases of COPD, including eight non-smokers and five with an FEV₁ < 80% of predicted values. Their average age was 54.6 ( ± 7.7) years and 10 of them were men. None complained of illness before the study. Multivariate analyses revealed no significant occupational risk factors for COPD.

Conclusions: This unexpected result may be because Breton dairy farms began to modernize early (1950s), giving rise to conditions with much lower exposure to airborne contaminants.