Risk Factors for Childhood Asthma and Wheeze: Comparisons from an International Study

Background and objectives: International differences in childhood asthma prevalence have been reported with the environment suspected to play a role. We sought to investigate risk factors for asthma and wheeze and their consistency between countries.Methods: This was an international, cross-sectional study of children (6-13 years) living in an urban centre from Belarus, Canada, Republic of Georgia (Adjara), Republic of Macedonia, Poland, and Ukraine. History of physician-diagnosed asthma and wheeze in the past 12 months were ascertained from parent completed survey. Basic survey information was standardized but each site could include questions on additional potential risk factors. Multiple logistic regression was used to adjust for confounding.Results: In total, 12257 children participated (response rates: 26%-91%). Asthma prevalence was highest in Canada (12.6%) followed by Poland (10.3%) then the remaining sites (range: 1.0%-1.5%). Wheeze prevalence followed similar patterns but was higher than asthma ...