SAN ANTONIO – Children living in the United States who were born elsewhere initially have lower rates of allergic disease than do those born in the United States, but the protection against allergic disease is lost after prolonged U.S. residence, according to an analysis of data from the 2007-2008 National Survey of Children’s Health.
Of 91,642 children aged 0-17 years who were included in the study, those born outside of the United States had significantly lower odds of having any allergic disorder, compared with those born in the United States (odds ratio, 0.48). They also had lower odds of all individual allergic disorders studied, including prior or current asthma (OR 0.53), current asthma (OR 0.34), eczema (OR 0.43), hay fever (OR 0.39), and food allergy (OR 0.60), Dr. Jonathan I. Silverberg reported at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
The association remained significant after adjustment for age, sex, race/ethnicity, household income, residence in metropolitan areas, and history of moving to a new U.S. residence, said Dr. Silverberg of St. Luke’s–Roosevelt Hospital Center, New York.
Also of note, the prevalence rates of allergic disease were lower for all of the diseases studied for children born outside of the United States whose parents were born outside of the United States, compared with those whose parents were born in the United States.
However, after 10 years or more of United States residence, children born outside of the United States had significantly higher odds of developing an allergic disorder, compared with those born outside of the United States who had lived in the country for only 0-2 years (OR 3.04). This was true for eczema (OR 4.93) and hay fever (OR 6.25), but not for asthma or food allergy, Dr. Silverberg said.
The study was undertaken in the wake of prior data showing that certain racial or ethnic groups have lower rates of allergic disease. Dr. Silverberg and his colleagues set out to investigate whether an association existed between birthplace, length of U.S. residence, and various allergic diseases.
The findings suggest that environmental factors promote the development of allergic disease, he concluded.
Dr. Silverberg reported having no relevant financial disclosures.