About 6 million U.S. children aged younger than 18 years have a food allergy and almost 40% have a history of severe reaction, data from a large nationally representative survey published online first in Pediatrics indicates.

Previous studies have estimated food allergy prevalence among U.S. children to be between 1% and 8%, with estimates from the 2005 National Health and Nutrition Examination Survey suggesting that food allergies affect 4.8% of children aged 1-to-5 years.

To validate these findings and better categorize allergy severity, Ruchi S. Gupta, MD, of Northwestern University in Chicago, and colleagues conducted a cross-sectional survey among a cohort of 38,480 children. Participants were aged a mean of 8 years; 56.4% were white, 21.6% were Hispanic, 14.1% were black and 4.8% were Asian.

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The researchers found that 8% of the study cohort had experienced a food allergy (95% CI 7.6 to 8.3) and the reaction was severe in 38.7%.

Peanuts allergies were the most common, affecting 2% of children surveyed (95% CI: 1.8 -2.2), followed by milk at 1.7% (95% CI: 1.5-1.8) and shellfish at 1.4% (95% CI: 1.2-1.5).

Severe allergic reactions including anaphylaxis, wheezing or low BP occurred in slightly more than half of all allergic reactions to peanuts and tree nuts.

Severe reactions were also common with shellfish (48.6%), soy (42.6%) and fin fish (40.6%).

Risk factors for having a severe reaction included male sex, the presence of multiple allergies, living in a higher income household and older age (P<0.05 for all). As children got older allergy prevalence increased, affecting 6.3% of children aged younger than 2 years and 8.6% of those aged 14 years and older.

“Consistent with past reports, this study found that odds of severe food allergy progressively increased with age, peaking at more than two-fold higher odds of severe reaction history among children ages 14 to 17 years vs. those ages 0 to 2 years,” the researchers wrote.

Additional multiple logistic regression analyses revealed that the likelihood of having a food allergy was higher among Asians (odds ratio= 1.4; 95% CI: 1.2-1.7) and blacks (OR=1.8; 95% CI: 1.6-2.1), but that these ethnicities were less likely to have received a formal food allergy diagnosis.

The researchers acknowledged participant recall bias as a potential study limitation, but noted that the findings “provide critical epidemiologic information to guide strategies for the prevention of food-induced reactions.”

Gupta R. Pediatrics. 2011;doi:10.1542/peds.2011-0204.