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J Asthma. 2017 Apr;54(3):239-249. doi: 10.1080/02770903.2016.1206564. Epub 2016 Jul 6.

Association of living in a farming environment with asthma incidence in Canadian children.

Author information

1
a School of Public Health, University of Alberta , Edmonton , Alberta , Canada.
2
b Division of Preventive Medicine, Department of Medicine, University of Alberta , Edmonton , Alberta , Canada.

Abstract

OBJECTIVE:

The objective of this population-based 14-year follow-up study was to examine the effect of living in a farm environment on asthma incidence in children.

METHODS:

A total of 10,941 children of ages 0 to 11 years who were free of asthma and wheeze at the baseline (1994-1995) in the National Longitudinal Survey of Children and Youth were considered in the study. Children's living environment was classified, based on interviewer's observation, into three categories: non-rural, rural non-farming, and farming. An incidence of asthma was obtained from health-professional diagnosed asthma reported either by the person most knowledgeable for children under 15 years or by the children themselves if they were of ages 16 years and over.

RESULTS:

The 14-year cumulative incidence of asthma among children living in farming environments was 10.18%, which was significantly lower than that observed for children living in rural non-farming (13.12%) and non-rural environments (16.50%). After adjusting for age group, number of older siblings, allergy, parental history of asthma, dwelling in need of repairs and SES index, a dose-response relationship was observed with children living in rural non-farming and farming environments having significantly reduced risk of asthma [hazard ratio (HR): 0.77; 95% confidence interval (CI): (0.60, 1.00); p = 0.047 and HR: 0.56; 95% CI: (0.41,0.77); p < 0.001] in comparison to those living in non-rural environments.

CONCLUSION:

This cohort study provides further evidence that living in a farming environment during childhood is protective of asthma incidence in adolescence and adulthood and this finding provides further support for the hygiene hypothesis.

KEYWORDS:

Adolescence; cumulative incidence; hygiene hypothesis; longitudinal study; rural; urban

PMID:
27383380
DOI:
10.1080/02770903.2016.1206564
[Indexed for MEDLINE]

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