Reduced risk of physician-diagnosed asthma among children dwelling in a farming environment.
OBJECTIVE
Living in a farm environment has been reported to be associated with lower prevalence of asthma, based on the results of cross-sectional studies. The objective of this longitudinal study was to determine whether living in a farm environment is associated with lower incidence of asthma among children.


METHODS
A total of 13 524 asthma-free children aged 0-11 years were drawn from the Cycle 1 (1994/1995) of the Canadian National Longitudinal Survey of Children and Youth (NLSCY). Subjects were categorized as dwelling in rural farming, rural non-farming and non-rural environments. Incidence of physician-diagnosed asthma was determined at Cycle 2 (1996/1997). Bootstrap logistic regression method was used to adjust for design effect in the NLSCY.


RESULTS
The 2-year cumulative incidence of asthma was 2.3%, 5.3% and 5.7% among children living in farming, rural non-farming and non-rural environments, respectively. From the multivariate analysis with adjustment for important confounders, children from a farming environment had a reduced risk of asthma compared with children from rural non-farming environment with odds ratios (OR) of 0.22 (95% CI: 0.07-0.74) and 0.39 (95% CI: 0.24-0.65) for children with and without parental history of asthma, respectively. Children living in a non-rural environment with parental history of asthma had an increased risk of asthma incidence when compared with children living in rural non-farming environment (OR = 2.51, 95% CI: 1.56-4.05).


CONCLUSIONS
This longitudinal study expands on observational study results which suggest a reduced risk of developing asthma associated with living in a farming environment.
Midodzi
William K
WK
Department of Public Health Sciences, School of Public Health, University of Alberta, Demonton, Alberta, Canada.
Rowe
Brian H
BH
Majaesic
Carina M
CM
Senthilselvan
Ambikaipakan
A
D000383:Agriculture; D001249:Asthma / Q000453:epidemiology*; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D015999:Multivariate Analysis; D012424:Rural Population / Q000706:statistics & numerical data*