Allergies less common in foreign-born U.S. kids

HealthDay News — Immigrant children living in the United States were significantly less likely to have allergies than children born here, but their odds for developing certain allergies increased if they stayed in the country a decade or longer, researchers found.

Among U.S. born children, 34.5% had allergies compared with 20.3% of foreign-born children living in the country (odds ratio=0.48; 95% CI: 0.38-0.61; P<0.001), Jonathan I. Silverberg, MD, PhD, MPH, from Beth Israel Medical Center and St. Luke’s-Roosevelt Hospital Center in New York City, and colleagues reported in JAMA Pediatrics.

The researchers distributed a cross-sectional questionnaire to 91,642 children aged 0 to 17 years, who were enrolled in the National Survey of Children’s Health, to examine the correlation between birthplace and prevalence of childhood allergic disease. 

They determined that foreign born children had lower chances of ever having asthma (OR=0.53; 95% CI: 0.39-0.72; P<0.001), current asthma (OR=0.34; 95% CI: 0.23-0.51; P<0.001), eczema (OR=0.43; 95% CI: 0.30- 0.61; P<0.001), hay fever (OR=0.39; 95% CI: 0.27-0.55; P<0.001) and food allergies (OR=0.60; 95% CI: 0.37- 0.99; P=0.045).

But this advantage disappeared after living in United States 10 or more years — during which time odds for any allergy increased to 3.04 (95% CI: 1.08-8.60) compared with U.S. born children. After adjustment for variables, including age, sex, race/ethnicity and residence in metropolitan areas, the correlation remained significant. For eczema the odds ratio increased 4.93 (95% CI: 1.18- 20.62; P=0.03) and for hay fever 6.25 (95% CI: 1.70-22.96; P=0.006)

Compared with foreign-born children living in the United States for less than two years, the odds of developing any allergic disorders, including eczema and hay fever, but not asthma or food allergies, were increased for immigrant children with 10 year residency (adjusted OR=3.04).

“In conclusion, foreign-born Americans have significantly lower risk of allergic disease than U.S.-born Americans,” the researchers wrote. “Further studies are needed to confirm these findings and to better understand allergic disease triggers in this group.”