Nearly 90% of food allergies resolve by age 6 but more research is needed on interventions for infants less likely to naturally outgrow their allergy.

Peanut and egg allergies are more likely to persist to age 6 in children with early-onset and severe eczema and multiple allergies, according to Rachel L. Peters, PhD.

“Little is known about prognostic biomarkers and risk factors for the persistence of food allergy, and clinicians are currently unable to accurately predict whether food allergy presenting in infancy will resolve naturally, or persist into adolescence and beyond,” says Dr. Peters.

For a study published in The Journal of Allergy and Clinical Immunology, Dr. Peters and colleagues evaluated the prevalence and natural history of peanut and egg allergies in children enrolled in the HealthNuts study, which included 5,276 participants recruited at age 1 who were followed prospectively. The study team assessed allergy-related trends among the children who were diagnosed with peanut (N=156) or raw egg (N=471) allergies. The cohort was followed-up at age 6 and participating children were evaluated for food sensitizations or food reactions, which yielded key findings about the natural history of peanut and raw egg allergies.

Close to 90% of Food Allergies Resolve by Age 6

Among the children with peanut allergies at age 1, approximately one-third experienced resolution of their peanut allergy by age 6. This percentage was significantly higher among those with egg allergies, with close to 90% experiencing resolution of their allergy by age 6.

The onset of a new peanut or egg allergy between ages 1 year and 6 years in children who were previously tolerant was < 1%. New-onset peanut allergies occurred in 0.7% (95% confidence interval [CI], 0.5%-1.1%) of children and new-onset egg allergies occurred in 0.09% (95% CI, 0.03%-0.3%) of children.

At age 6, the prevalence of peanut allergy was 3.1% (95% CI, 2.6%-3.7%), which was similar to the prevalence of peanut allergy observed at age 1, also 3.1% (Table). “Although 29% of peanut allergy diagnosed at age 1 resolved by age 6, the prevalence of peanut allergy at age 6did not c from what we previously reported at age 1, and this was largely driven by new-onset peanut allergy that occurred after age 1,” Dr Peters notes. In contrast, the 1.2% (95% CI, 0.9%-1.6%) prevalence of egg allergy at age 6 was significantly lower than the previously reported prevalence at age 1 of 9.5%, because most cases resolved, and new-onset egg allergies were rare.

Eczema, Food Sensitizations Highly Tied to Peanut & Egg Allergy Persistence

Several demographic and clinical factors were found to be more common in children with persisting peanut allergies at age 6, including having at least one Asian parent, having an eczema diagnosis at age 1, showing sensitization to one or more tree nut/other types of food/house dust mites, and having a lower cumulative reaction-eliciting dose in peanut oral food challenge at age 1 versus those with a resolved peanut allergy.

The age at which peanut introduction occurred was not found to predispose one to allergy persistence. In adjusted models, the presence of early-onset severe eczema was associated with a more than three-fold increased risk for peanut allergy persistence, whereas sensitization to tree nuts at age 1 was linked with a 2.5-fold increased risk for persistence.

Several predictors for persistent egg allergies mirrored those for persistent peanut allergies, including having at least one Asian parent, having an eczema diagnosis at age 1, showing sensitization to one or more other types of food, and having a lower cumulative reaction-eliciting dose at age 1 versus those with resolved egg allergy. Other factors associated with persistent egg allergies included being assigned male sex at birth and having an allergy to baked egg.

Skin Prick Test Poor Predictor of Peanut & Egg Allergy Persistence at 6 Years

Overall, skin prick test (SPT) responses at age 1 were found to be poor predictors of both peanut and egg allergy persistence at 6 years. A peanut SPT result of 8 mm or more at age 1 was determined to be the threshold that maximized SPT sensitivity and specificity (67% and 54%, respectively). Patients who reached this threshold were found to have a 2.35-fold increased risk for persistent peanut allergy at age 6. In the setting of an egg SPT, the optimal threshold was determined to be 4 mm or greater. Patients with results meeting this threshold at age 1 had an almost three-fold increased risk for persistent egg allergy at age 6.

“Infants with larger SPT wheal sizes, eczema, or multiple food sensitizations are less likely to outgrow their egg or peanut allergy by age 6,” Dr. Peters says. “Disease-modifying interventions such as oral immunotherapy in early life may be best targeted to infants with these findings, as they are less likely to develop tolerance naturally. Prioritizing research of these and future interventions for infants less likely to naturally outgrow their allergy would yield the most benefit for healthcare resources and research funding.”