Atopic and non-atopic asthma in a farming and a general population

Background In a previous study inverse associations between asthma and exposure to fungal spores and endotoxins in atopic farmers and positive associations with the same factors in non‐atopic farmers were documented. No external reference population had been included. We, therefore, compared this farming population with the general population from an adjacent region. Methods Random samples of a farming (n = 2,106) and a rural (n = 351) and urban (n = 727) general population were selected. Atopy was assessed by serum IgE and asthma by questionnaires. Results The asthma prevalence was 4.0% among farmers, 5.7% in the rural, and 7.6% in the urban population. Atopy was similar (9–10%). Most asthmatics were not atopic, 67–75%. Farmers had asthma less often than the general population OR 0.52 (95% CI 0.36–0.75); both atopic (OR 0.33 (95% CI 0.15–0.69)) and non‐atopic asthma (OR 0.60 (95% CI 0.39–0.93)). Conclusion This may indicate a protective effect of the farm environment on asthma but a healthy worker effect may also play a role. Am. J. Ind. Med. 46:396–399, 2004. © 2004 Wiley‐Liss, Inc