LATE-BREAKING ABSTRACT: The urban-rural gradient of allergic asthma in adults

Abstract

Background: The reported prevalence of allergic asthma is low among farmers and children living on a farm as opposed to non-allergic asthma. Aim: The aim was to investigate the urban-rural differences of allergic and non-allergic asthma in adults depending on four different childhood exposure environments. Methods: A total of 1236 male participants of 30-40 years of age recruited from two epidemiological studies (SUS and Health2006) were categorized into four groups with regard to place of upbringing; city, town, rural area, and farm. Allergic sensitization was assessed by skin prick tests (SPTs) to 10 inhalant allergens and measurements of serum specific IgE (sIgE) to four inhalant allergens (grass, birch, cat, and house dust mite). Ever asthma was defined from the question “did you ever have asthma” for both studies. Allergic asthma was defined as having asthma and being sensitized to one or more allergens measured by either IgE or SPT. Results: Allergic asthma decreased with decreasing degree of urbanized upbringing see Table 1. Conclusion: This is the first study to show an urban rural gradient of allergic asthma in adults depending on their childhood exposure. In this highly homogenous Western population exposure to a less urbanized childhood was associated with lower risk of allergic asthma in adulthood.