New Insights Into Course of Childhood Food Allergy

SAN FRANCISCO — Egg allergies in infants only rarely lasted till age 6 in an Australian longitudinal study, and peanut allergies resolved in nearly a third, researchers said here.

Among children whose allergies were confirmed at age 1 through challenge testing, peanut allergy was no longer present in 31% (95% CI 24%-40%) and egg allergy resolved in 89% (95% CI 85%-92%) when they were examined 5 years later.

The 5,300 children in the Australian HealthNuts cohort study, who are now about age 10 years, were part of the first comprehensive population-based study of food allergy with objective food allergy measurement. Findings were presented by Rachel Peters, PhD, of Murdoch Children’s Research Institute, Parkville, Australia, during a late-breaking research presentation at the American Academy of Asthma, Allergy & Immunology annual meeting.

HealthNuts was designed to examine the natural history of allergic disorders including food allergy, asthma, eczema, and hay fever and the risk factors for developing these conditions in childhood. At age 1, peanut allergies were confirmed through challenge in 156 children, and 468 had confirmed egg allergy.

Parents were surveyed through questionnaires when the children were ages 4 and 6 years, and the children were also invited back for an allergy health check at age 6 years. Children with skin prick test (SPT) results of 8 mm or greater and positive oral food challenge at age 4 years were considered persistent allergic at age 6 without challenge.

Peters and colleagues found that SPT measured at age 1 was a poor predictor of persistent food allergy at age 6, with areas under the receiver-operating characteristic curve less than 0.70.

Eczema at age 1 was associated with persistent food allergy (peanut: adjusted OR 2.74, 95% CI 1.13-6.62; egg: adjusted OR 3.53, 95% CI 1.31-9.47). Tree nut sensitization at age 1 was associated with persistent peanut allergy (adjusted OR 2.63, 95% CI 0.99-6.96).

In addition to shedding new light on the natural history of peanut and egg allergies in early life, the analysis also identified key early life risk factors associated with persistent food allergy, Peters told attendees. Besides eczema and tree nut sensitization at age 1, these included a peanut SPT result of <4 mm.

Having any of these was associated with a 45%-50% probability of having a persistent peanut allergy at age 6, and having two led to a probability of 70%-74%. Children with all three were 95% likely to still show peanut allergy at age 6.

For egg allergy, early eczema, peanut allergy, and having gastrointestinal symptoms or respiratory symptoms in response to eating egg all predicted persistent allergy.

But egg-allergic 1-year-olds with just one of the risk factors still had a very low (4%-6%) probability of having persistent egg allergy as 6-year-olds, and fewer than half (45%) of children with all identified risk factors at age 1 year still exhibited symptoms at age 6.