PURPOSE OF THE STUDY.
The goal of this study was to gauge the natural history of egg allergy in a population-based cohort and to identify factors predicting persistence.
Children (n = 264) determined to be allergic to raw eggs (according to results of skin testing and oral food challenge) were recruited during February 2010 to August 2011 from the HealthNuts study, a prospective, population-based cohort of food-allergic children recruited at age 12 months (N = 5267) during immunization sessions in Melbourne, Australia.
Egg-allergic infants were offered a baked egg oral food challenge to phenotype them as baked egg tolerant and baked egg allergic. At age 2 years, all infants were invited for repeat oral food challenge to raw egg, skin prick testing (SPT), and egg-specific IgE testing. A survey was administered (by telephone or in the clinic) at ages 1 and 2 years to determine the frequency of baked egg ingestion.
A total of 140 of 264 infants participated in the follow-up at age 2 years. Egg allergy resolved in 47% (95% confidence interval: 37–56) by age 2 years. Of those patients who were baked egg tolerant at 1 year of age, 56% experienced resolution of their egg allergy compared with only 13% with baked egg allergy (P = .02). Those infants classified as baked egg tolerant who had frequent consumption (≥5 times/month) of baked products were more likely to resolve their egg allergy compared with those with infrequent (0–4 times/month) consumption (adjusted odds ratio: 3.52 [95% confidence interval: 1.38–8.98]; P = .009). After adjusting for confounders, SPT of ≥4 mm and egg-specific IgE ≥1.7 kUA/L were the only 2 measures (P = .003) predictive of egg allergy persistence.
In this community-based population cohort, nearly one-half of all challenge-confirmed egg-allergic infants were egg tolerant at 2 years of age; however, the percentage of resolution was significantly increased for those with the baked egg–tolerant phenotype at age 1 year and for those with frequent consumption of baked egg products. Although the baked egg–tolerant phenotype is predictive of egg allergy resolution, SPT and egg-specific IgE aided in predicting persistence of egg allergy.
This study is the first of its kind to evaluate the natural history of egg allergy in infants at the community level. Previous studies have evaluated egg-allergic children from subspecialty cohorts in which severe allergic disease is more highly represented, possibly leading to a higher average age at which tolerance to egg develops. This study highlights the importance of a detailed dietary history during initial egg allergy assessment as continued dietary ingestion of baked egg for those who tolerate it without allergic symptoms predicts possible earlier resolution. The differences observed in raw egg tolerance development between the baked egg–allergic and baked egg–tolerant phenotypes also have important implications for future studies in egg oral immunotherapy.
- Copyright © 2014 by the American Academy of Pediatrics