Sensitization is more prevalent among parents of food allergic children than in the general population, new research shows. But parents’ self-reported food allergies correlated poorly with specific IgE (sIgE) levels, Dr. Rachel Robison of Northwestern University Feinberg School of Medicine in Chicago and her colleagues found.
“Our study highlights the potential flaw in using self-report as a surrogate for food allergy diagnosis. It also highlights the need to confirm diagnosis with testing and in appropriate settings to perform oral food challenges as a gold standard for diagnosis due to the high false positive rate seen with both skin and blood testing for food allergy,” Dr. Robison told Reuters Health via email.
The findings were published online October 12 in the Annals of Allergy, Asthma, and Immunology.
The National Health and Nutrition Examination Survey (NHANES) for 2005-2006 found that 44.6 percent of U.S. adults had serum sIgE levels to at least one of 19 allergens. To better understand inherited patterns of food and aeroallergen sensitization, Dr. Robison and her team looked at 1,252 mothers and 1,225 fathers participating in a family-based study of food-allergic children.
Overall, 13.7 percent of parents (14.5 percent of mothers, 12.7 percent of fathers) reported having a food allergy, while two-thirds were sensitized to a food or an aeroallergen. Among the parents who reported having a food allergy, 28.4 percent were actually sensitized to that food allergen. Sensitization among those reporting an allergy ranged from 10.7 percent to fish to 55.6 percent for peanut.
Compared to the NHANES data for 30 to 39-year-olds, the study participants (mean age 37.9 years) were more likely to be sensitized to peanut, shrimp, milk, or egg.
“While positive test results were more common in parents of children with known food allergy, the actual levels in the blood for the foods were quite low,” Dr. Robison noted. “In previous studies, these low levels do not always result in a true allergic reaction to a food and can be false positives or simple sensitization.”
She and her colleagues conclude: “Our study suggests that using parental report of food allergy as a risk factor is unreliable. Other known risk factors, such as infant eczema, may be better for predicting the risk of future food allergy in a child. More epidemiologic studies of food allergy in the adult population that include proper testing and food challenge outcomes are needed to better understand sensitization and heritability.”