Environmental factors, parental atopy and atopic eczema in primary-school children: a cross-sectional study in Taiwan

Summary Background Parental atopy and environmental exposure are recognized risk factors for atopic eczema (AE) in childhood. However, the relative contributions of specific risk factors and the overall contributions of hereditary and environmental exposure remain unexplored. Objectives To identify risk factors, estimate the population attributable risk (PAR) of environmental exposure, and compare the AE data for boys vs. girls in primary-school children. Methods During a February to June 2001 cross-sectional, Taiwan-based questionnaire survey, we investigated 23 980 children from 22 primary schools, all located within 1 km of an air-monitoring station. Results The 12-month prevalence of AE was reported as 6·1% in boys and 4·9% in girls. In both sexes, the risk of AE was strongly associated with parental atopy and perceived ambient air pollution. The presence of cockroaches [odds ratio (OR) 1·18, 95% confidence interval (CI) 1·00–1·40] and visible mould on walls at home (OR 1·46, 95% CI 1·22–1·70) were also significantly related to AE for girls; however, only visible mould on walls (and not the presence of cockroaches) at home was related to AE for boys (OR 1·40, 95% CI 1·18–1·66). While mutually adjusted models were applied, we found adjusted ORs and PARs were similar in boys and girls in hereditary and outdoor environmental factors. The PAR of indoor environmental factors was higher in girls (8·4%) than in boys (5·5%). There was no interaction between parental atopy and environmental factors. Conclusions Parental atopy contributed more to AE than indoor or outdoor environmental factors. Girls may be more susceptible to indoor environmental factors than boys.