Bronchial hyperresponsiveness in farmers: relation to respiratory symptoms, lung function, and atopy

There is only limited information on the factors associated with nonspecific bronchial hyperresponsiveness (BHR) in farmers. Our purpose was to examine the relationship between BHR and respiratory symptoms, atopy, and abnormalities of lung function in a sample of French farmers. Farmers scheduled for a preventive medicine check-up in northeastern France were examined. Occupational exposure, respiratory symptoms, and work-related symptoms were assessed by questionnaire, sensitization to 34 common and agricultural allergens by skin prick tests, and BHR by the single-dose (1,200 microg) acetylcholine (ACh) challenge test. Data were obtained from 741 farmers (95% of those invited). Seventy-seven subjects (10.3%) had BHR defined as a fall in forced expiratory volume in 1 s (FEV1) >/= 10% after the inhalation of ACh or, for those with a poor lung function, an increase in FEV1 > 10% and > 200 ml after the inhalation of 200 microg of salbutamol. The proportion of asthmalike symptoms, especially wheeze during work, positive skin tests to acarian (storage mites) and cereal dust allergens, and low levels of lung function was significantly greater among reactors than among nonreactors. Stepwise logistic regression analysis showed a significant and independent association between BHR and wheezing during work (OR = 4.99; 95% CI = 2.29-10.89; p = 0.0001) and baseline FEV1 (OR = 1.49; 95% CI = 1.05-2.20; p = 0.026). In conclusion, hyperreactive farmers had significantly more asthmalike symptoms, positive skin tests, and abnormal lung function than normoreactive farmers. Work-related wheeze and low baseline FEV1 were significantly and independently associated with BHR.