Childhood farm environment and asthma and sensitization in young adulthood.
BACKGROUND
Farm environment in childhood may protect against sensitization, allergic rhinitis, and asthma.


METHODS
Subjects were obtained from 10 667 Finnish first-year university students who responded to a questionnaire survey on IgE-mediated diseases. Two random samples were selected from 1631 respondents in Turku: subjects with asthma or wheezing, and subjects without asthmatic symptoms. A total of 296 subjects (72%) participated. Skin prick tests (SPT), measurements of IgE-antibodies, methacholine challenge, and bronchodilation tests were performed. Weighted occurrence of current asthma and sensitization among students from "childhood farm" and "childhood nonfarm" environments were analyzed.


RESULTS
Current asthma was found in 3.1% of subjects with childhood farm environment, and in 12.4% with nonfarm environment (odds ratio (OR) 0.22; 95% confidence interval (CI) 0.07-0.70). There were fewer positive SPT to birch (8.3 vs. 24.2%, OR 0.28, 95% CI 0.07-1.15) and timothy pollen (12.6 vs. 30.3%, OR 0.33, 95% CI 0.09-1.20) among subjects with childhood farm environment, but more sensitization to house-dust mite (22.0 vs. 4.9%, OR 5.43, 95% CI 1.60-18.46). Sensitization to cat (RAST class >/= 3) was less common in subjects with farm compared to nonfarm environments in childhood (1.5 vs. 13.1%; OR 0.10, 95% CI 0.02-0.47).


CONCLUSIONS
Farm environment in childhood protects against adult asthma and sensitization-especially to cat-the most important asthma related allergen. In contrast, sensitization to house-dust mite was more common in farming subjects.
Kilpeläinen
M
M
Department of Pulmonary Diseases and Clinical Allergology, University of Turku, Finland.
Terho
E O
EO
Helenius
H
H
Koskenvuo
M
M
D000293:Adolescent; D000328:Adult; D000818:Animals; D000829:Animals, Domestic / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D001249:Asthma / Q000209:etiology* / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000276:immunology / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents / Q000009:adverse effects; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005387:Finland; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007114:Immunization; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D008297:Male; D016210:Methacholine Chloride / Q000009:adverse effects; D011852:Radioallergosorbent Test; D012129:Respiratory Function Tests; D012572:School Health Services; D012720:Severity of Illness Index; D012882:Skin Tests; D011795:Surveys and Questionnaires
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D007073:Immunoglobulin E