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Parental farming protects children against atopy: longitudinal evidence involving skin prick tests
Author(s) -
Horak F.,
Studnicka M.,
Gartner C.,
Veiter A.,
Tauber E.,
Urbanek R.,
Frischer T.
Publication year - 2002
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1046/j.1365-2745.2002.01448.x
Subject(s) - atopy , allergy , odds ratio , medicine , confounding , agriculture , confidence interval , sensitization , demography , incidence (geometry) , environmental health , pediatrics , immunology , ecology , biology , physics , sociology , optics
Summary Background There is growing evidence that the development of allergic sensitization can be influenced by environmental co‐factors. Studies showed that growing up on a farm can protect children against allergic sensitization. However, little is known whether this ‘farming effect’ can only be observed in early lifetime or whether it also plays a role in later childhood. Objective The aim of our study was to test whether a farming environment is negatively associated with a new occurrence of skin prick test (SPT) positivity in school children. As a secondary outcome we investigated whether children living on a farm lose their allergic sensitization more frequently than other children. Methods In a longitudinal design, 1150 elementary school children (mean age 7.8 years, SD 0.7) were recruited from nine different areas of Austria in 1994. A questionnaire and an SPT involving seven common aero‐allergens were performed at study entry and at follow‐up 3 years later. Results A total of 844 children, who underwent two SPTs, were included in the analyses; 15.1% of their families reported working on a farm. Adjusting for potential confounders (parental education, number of siblings, sex, family history of allergy), parental farming was inversely related to the prevalence and new occurrence of SPT positivity [no farming 12.2%, part‐time farming 6%, full‐time farming 2.2% incidence; odds ratio (OR) farming vs. non‐farming 0.34, 95% confidence interval (CI) 0.12–0.98]. Furthermore, children living in a farming environment were more likely to lose their SPT positivity during follow‐up (no farming 14.6%, part‐time farming 50%, full‐time farming 60% loss of sensitization; OR farming vs. non‐farming 8.06; 95% CI 2.05–31.75). No difference in the pattern of sensitization to specific allergens could be observed between farming and non‐farming children. Conclusion A farming environment has a strong negative effect on the development of allergic sensitization. Furthermore, the study provides evidence that atopic children living on a farm lose their SPT positivity more frequently than children from non‐farming environments.