Considered “transitional” a generation ago, milk and egg allergies now appear to be more persistent and harder to outgrow, according to new research from the Johns Hopkins Children’s Center.
In what are believed to be the largest studies to date of children with milk and egg allergies, researchers followed more than 800 patients with milk allergy and nearly 900 with egg allergy over 13 years, finding that, contrary to popular belief, most of these allergies persist well into the school years and beyond. Reports on the two studies appear in the November and December issues of the Journal of Allergy and Clinical Immunology.
“The bad news is that the prognosis for a child with a milk or egg allergy appears to be worse than it was 20 years ago,” says lead investigator Robert Wood, M.D., head of Allergy & Immunology at Hopkins Children’s. “Not only do more kids have allergies, but fewer of them outgrow their allergies, and those who do, do so later than before.”
Researchers caution that their findings may reflect the fact that relatively more severe cases end up at Hopkins Children’s, but they believe there is a trend toward more severe, more persistent allergies.
The findings also give credence to what pediatricians have suspected for some time: More recently diagnosed food allergies, for still-unknown reasons, behave more unpredictably and more aggressively than cases diagnosed in the past. “We may be dealing with a different kind of disease process than we did 20 years ago,” Wood says. “Why this is happening we just don’t know.”
Earlier research suggested that three-quarters of children with milk allergy outgrew their condition by age 3, but the Johns Hopkins team found that just one-fifth of children in their studies outgrew their allergy by age 4, and only 42 percent outgrew it by age 8. By age 16, 79 percent were allergy-free.
Similar trends were seen in the egg-allergy group. Only 4 percent outgrew this allergy by age 4, 37 percent by age 10, and 68 percent by age 16.
The Hopkins Children’s team found that a child’s blood levels of milk and egg antibodies—the immune chemicals produced in response to allergens—were a reliable predictor of disease behavior: The higher the level of antibodies, the less likely it was that a child would outgrow the allergy any time soon. Pediatricians should use antibody test results when counseling parents about their child’s prognosis, researchers say.
One encouraging finding: Some children lost their allergies during adolescence, which is later than believed possible, suggesting that doctors should continue to test patients well into early adulthood to check if they may have lost their allergies.
Milk and egg allergies are the two most common food allergies in the United States, affecting 3 percent and 2 percent of children, respectively.
Co-investigators in the two studies: Justin Skripak, M.D., Jessica Savage, M. D., Elizabeth Matsui, M.D., M.H.S, Kim Mudd, R.N., all of Hopkins Children’s.
The studies were funded in part by the National Institutes of Health and supported by the Eudowood Foundation, the Food Allergy Initiative and Julie and Neil Reinhard. Wood is a consultant for Dey Pharmaceuticals and has received support from Merck and Genentech.