Characterisation of asthma among adults with and without childhood farm contact

¹ Institute for Occupational and Environmental Medicine, Unit for Occupational and Environmental Epidemiology & Net Teaching, Ludwig-Maximilians-University, Munich; and GSF-National Research Centre for Environment and Health, Institute of Epidemiology, Neuherberg, Germany
² Institute for Occupational and Environmental Medicine, Unit for Occupational and Environmental Epidemiology & Net Teaching, Ludwig-Maximilians-University, Munich; and Municipal Health Service Amsterdam, Department of Environmental Medicine, Amsterdam, the Netherlands
³ Institute for Occupational and Environmental Medicine, Unit for Occupational and Environmental Epidemiology & Net Teaching, Ludwig-Maximilians-University, Munich

^* To whom correspondence should be addressed. E-mail: Katja.Radon{at}med.uni-muenchen.de.

	Abstract

Farm childhood was shown to be associated with a lower prevalence of sensitisation and allergic rhinitis. For asthma findings have been contradictory. We aimed to study these differences between farm and non-farm subjects using objective measurements.

A cross-sectional questionnaire study was done among rural adults (18-45 years old, 37% living on a farm during the first three years of life ("farm subjects")). Lung function, bronchial hyperresponsiveness to methacholine (BHR) and sensitisation were measured in a random sample. Overall, 1595 subjects could be included in the analyses.

Among farm subjects, sensitisation against inhalant allergens (odds ratio 0.7; 95% confidence interval 0.6, 0.9), allergic rhinitis (0.5; 0.4, 0.8), and asthma diagnosis (0.7; 0.4, 1.1) were less common than among non-farm subjects. For BHR and lung function no statistically significant differences between the two groups were found. Stratifying for sensitisation, farm subjects had a lower odds ratio of asthma diagnosis (0.5; 0.3, 1.0) and a not significantly reduced odds ratio of BHR with sensitisation (0.8; 0.5, 1.1).

Our study confirms using objective measurements that farm subjects have a lower prevalence of symptoms and asthma diagnosis while the prevalence of BHR does not differ.

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