Abstract
Background: Estimates of asthma incidence and its determinants have rarely been obtained from rural regions, especially in adolescent populations.
Objective: To compare the incidence of asthma among Canadian adolescents in rural and urban regions and to examine the determinants of asthma incidence.
Methods: We used data from the National Population Health Survey (NPHS), a nationally representative longitudinal survey of Canadians. The NPHS uses a complex survey design with data collected every 2 years since 1994/95. The NPHS collects information on socio-demographics and some health behaviours. All persons aged 12-18 years without asthma in Cycle 1 were followed until a reported diagnosis of asthma or censoring up to Cycle 7. Rural residence was defined by living in an area of <1000 people and >400 people/km2. Incidence and Cox regression analyses were population weighted and bootstrapping procedures were used to estimate variances.
Results: This sample represented 2,482,610 adolescents of whom 293,445 developed asthma. Approximately 19% of the cohort was rural living at baseline. The incidence of asthma was approximately 10.2 per 1000 person-years and was higher in urban dwellers than rural dwellers (10.9 vs. 7.7 per 1000 person-years). In adjusted analysis, rural residence was not associated with asthma development [Hazard ratio (HR)=0.58, 95%CI=0.25-1.32, p=0.19]. Being female and being exposed to passive smoking were both associated with the development of asthma (p<0.01).
Conclusions: Unlike results from younger children, a rural dwelling was not protective of developing asthma among adolescents, despite showing a trend. Asthma prevention initiatives for adolescents should target girls and focus on smoking exposure.
- © 2011 ERS
