Scientific Study

BACKGROUND: Asian children born in Australia have higher rates of eczema and nut allergy than non-Asian children. However, it is not known whether this country of birth differential exists for other allergies or anaphylaxis risk. OBJECTIVE: We investigated the influence of maternal and child's country of birth on the prevalence of parent-reported eczema, asthma, food allergy, and being diagnosed by a doctor as being "at risk of anaphylaxis". METHODS: We assessed the relationship between mother and child country of birth and allergies using the 2010 School Entrant Health Questionnaire, completed for 57,005 5-year old children (85.8% response rate) in Victoria, Australia. Analyses were conducted using logistic regression with results presented as odds ratios (OR) with 95% confidence intervals (CIs). RESULTS: Children born in Australia to Asian-born mothers were more likely to have parent-reported food allergy (OR 2.33, 95%CI 1.96-2.77) and eczema (OR 2.04, 95%CI 1.73-2.41), but not more likely to have asthma (OR 0.87, 95% CI 0.74-1.02) than non-Asian children. By contrast, children born in Asia who subsequently migrated to Australia had a lower risk of food allergy (OR 0.33, 95%CI 0.20-0.55), eczema (OR 0.37, 95%CI 0.24-0.57) and asthma (OR 0.29, 95% CI 0.21-0.40). Patterns of anaphylaxis risk differed depending on the trigger. Compared with Australian-born non-Asian children, Australian-born Asian children were more likely to be diagnosed as being at risk of both food-induced and non-food induced anaphylaxis. For children born in Asia, risk was lower for anaphylaxis to milk, peanut and tree nuts compared to non-Asian children, but higher for soy, wheat and non-food triggers. CONCLUSIONS & CLINICAL RELEVANCE: Patterns of allergy/anaphylaxis risk and their triggers differed according to both ethnicity and country of birth, suggesting a gene-environment factor is in play. The difference in patterns for asthma compared with other atopic diseases is surprising and warrants further exploration.