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

Abstract

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 (3.7% to 14.0%). In adjusted analyses using data from sites with the most comprehensive information (Canada, Poland, Macedonia), we found increased risk of asthma associated with antibiotic use, traditional medicine use, home mould or dampness, and family history of allergic conditions but a lower risk with being female (p<0.05). Similar results were seen when considering the outcome wheeze except that exposure to mice or pests increased the risk of wheeze and there was no association with home mould. There were some statistically significant interactions suggesting that the associations were not consistent between sites. Finally, when comparing no asthma or wheeze to those with wheeze without asthma as well as comparing no asthma or wheeze to those with asthma, risk factors were similar.Conclusions: Our findings suggest that in general, risk factors for asthma or wheeze are similar to what we expect but that some of these may be specific to certain locations.