The combined effects of family size and farm exposure on childhood hay fever and atopy. Issue 3 (3rd April 2013)

• Record Type: Journal Article
• Authors: Genuneit, Jon; Strachan, David P.; Büchele, Gisela; Weber, Juliane; Loss, Georg; Sozanska, Barbara; Boznanski, Andrzej; Horak, Elisabeth; Heederik, Dick; Braun‐Fahrländer, Charlotte; von, Erika
• Is Part Of: Pediatric allergy and immunology. Volume 24:Issue 3(2013)
• Page Start: 293
• Page End: 298
• Publication Date: 2013-04-03
• Subjects: Allergy in children -- Periodicals; Immunologic diseases in children -- Periodicals; 617
• DOI: 10.1111/pai.12053
• Languages: English
• ISSNs: 0905-6157

Abstract

<abstract abstract-type="main" xml:lang="en" id="pai12053-abs-0001"> <title>Abstract</title> <sec id="pai12053-sec-0001" sec-type="section"> <title>Background</title> <p>Exposure to farming environments and siblings is associated with reduced risks of childhood hay fever and atopy. We explored the independence and interaction of these protective effects in the GABRIELA study.</p> </sec> <sec id="pai12053-sec-0002" sec-type="section"> <title>Methods</title> <p>Questionnaire surveys on farming, asthma, and allergies were conducted in four central European areas among 79, 888 6–12‐yr‐old children. Aeroallergen‐specific serum IgE was measured in a stratified sample of 8, 023 children. Multiple logistic regression was used to compare gradients in allergy prevalence by sibship size across three categories of exposure to farming environments.</p> </sec> <sec id="pai12053-sec-0003" sec-type="section"> <title>Results</title> <p>The prevalence of hay fever ranged from 2% (95% confidence interval 1.6%; 2.7%) among farmers' children with more than two siblings to 12% (11.2%; 13.0%) among children with no farm exposure and no siblings. Farming families were larger on average. More siblings and exposure to farming environments independently conferred protection from hay fever and atopy. There was no substantial effect modification between family size and exposure to farming environments. The odds ratios for hay fever per additional sibling were 0.79 among unexposed non‐farm children, 0.77 among farm‐exposed non‐farm children, and 0.72 among children from farming families (2df interaction test: p = 0.41).</p> </sec> <sec id="pai12053-sec-0004" sec-type="section"> <title>Conclusion</title> <p>The inverse association of exposure to farming environments with hay fever is found in all sizes of family, with no substantial tendency to saturation or synergism. This suggests that different biological mechanisms may underlie these two protective factors. Combinations of a large family and exposure to farming environments markedly reduce the prevalence of hay fever and indicate the strength of its environmental determinants.</p> </sec> </abstract>