The natural history of egg allergy in an observational cohort

Abstract

Background: There are few studies on the natural history of egg allergy, and most are single-site and nonlongitudinal and have not identified early predictors of outcomes.

Objective: We sought to describe the natural course of egg allergy and to identify early prognostic markers.

Methods: Children age 3 to 15 months were enrolled in a multicenter observational study with either (1) a convincing history of an immediate allergic reaction to egg, milk, or both with a positive skin prick test (SPT) response to the trigger food and/or (2) moderate-to-severe atopic dermatitis and a positive SPT response to egg or milk. Children enrolled with a clinical history of egg allergy were followed longitudinally, and resolution was established based on successful ingestion.

Results: The cohort with egg allergy consists of 213 children followed to a median age of 74 months. Egg allergy resolved in 105 (49.3%) children at a median age of 72 months. Factors that were most predictive of resolution included the following: initial reaction characteristics (isolated urticaria/angioedema vs other presentations), baseline egg-specific IgE level, egg SPT wheal size, atopic dermatitis severity, IgG4 level, and IL-4 response (all P < .05). Numerous additional baseline clinical and demographic factors and laboratory assessments were not associated with resolution. Multivariate analysis identified baseline egg-specific IgE levels and initial reaction characteristics as strongly associated with resolution; a calculator to estimate resolution probabilities using these variables was established.

Conclusions: In this cohort of infants with egg allergy, approximately one half had resolved over 74 months of follow-up. Baseline egg-specific IgE levels and initial reaction characteristics were important predictors of the likelihood of resolution.

Keywords: AD; Atopic dermatitis; CoFAR; Consortium of Food Allergy Research; Ct; Cycle threshold; Egg allergy; HR; Hazard ratio; IgE; OFC; Oral food challenge; SPT; Skin prick test; food allergy; natural history.

Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

Figures

Figure 1

Kaplan-Meier analysis of egg allergy resolution over time with point-wise 95% confidence intervals

Figure 2

Kaplan-Meier analysis representing the relationship of egg allergy resolution to baseline egg-specific IgE levels. Individual curves represent IgE levels of A/L (blue), 2 – 10 kUA/L (red), and ≥ 10 kUA/L (green).

Figure 3

Kaplan-Meier Analysis representing the relationship of egg allergy resolution to clinical presentation of initial reactions to egg. The mutually exclusive clinical presentation of the initial reaction to egg ingestion was categorized as the following: AD diagnosis (flare of AD; this category included egg-IgE > 2 kUA/L), skin only (acute hives and/or angioedema) or systemic (e.g., more than isolated skin, including respiratory and gastrointestinal reactions).