Ethnicity, childhood environment and atopic disorder

Background The International Study of Asthma and Allergies in Childhood (IS AAC) has demonstrated large differences in the prevalence of atopic disorde rs in children between different regions in the world. Populations with a h igher standard of living and a more westernized lifestyle tend to have high er rates of atopy and asthma. Many hypotheses regarding environmental cause s of atopic disorder focus on the early childhood environment. Objective To study the influence of ethnicity and country of birth for the prevalence of atopic disorders. Methods The prevalence of atopic disorders in Swedish residents born in Tur key and Chile, who settled in Sweden as adults in the 1980s, was compared w ith their own Swedish-born children and a sample of Swedish-born parents an d their children in interview data from the Survey of Living Conditions in 1996. The study group included 1734 adults 27-60 years of age and their 296 4 children aged 3-15. Results The Chilean-born parents and their children had the highest risk fo r allergic asthma; adjusted odds ratios (ORs) 2.2 (1.2-4.0) and 2.7 (1.6-4. 5), respectively, and allergic rhino-conjunctivitis; OR 1.6 (1.1-3) and 1.6 (1.1-2.5) in both groups, when compared with the Swedish-born parents and their children. The Turkish-born parents and their children had the lowest risk for allergic rhino-conjunctivitis; both groups had OR 0.6 (0.4-0.9) an d the children in this group also had the lowest risk for eczema; OR; 0.4 ( 0.3-0.7). The risk for all atopic disorders was lower in the Turkish group compared with the Chileans. Conclusion This study demonstrates that ethnicity is an important determina nt of atopic disorder independent of the external childhood environment. Th e value of international comparisons of environment and risk for atopic dis orders can be questioned until more is known about factors related to ethni city, such as genetic susceptibility and diet, for the development of atopy .