Clinical Significance of Egg Sensitization in Pediatric Food Protein-Induced Enterocolitis Syndrome to Hen's Egg

Abstract

Background: Hen's egg, a common IgE-mediated food allergen, is an increasingly common food protein-induced enterocolitis syndrome (FPIES) trigger. Atypical FPIES is defined as detectable IgE to the food causing FPIES.

Objective: To evaluate clinical characteristics, natural history, baked egg tolerance, and FPIES challenge outcomes based on allergic sensitization status in patients with egg FPIES.

Methods: This retrospective, dual-center cohort study examined children with the diagnosis of egg FPIES by an allergist. We reviewed charts for reaction characteristics, atopic history, allergic sensitization to egg, baked egg tolerance, and food reintroduction outcomes.

Results: Of 153 patients with FPIES, 124 underwent egg allergy testing and 56 (36.6%) were sensitized to egg. Skin testing and food reintroduction varied based on practice and patient preferences. Of 48 patients who introduced baked egg, 30 (62.5%) tolerated it after a median of 20.5 months (interquartile range, 13.25-33 months) of avoidance. Including those tolerating baked egg at presentation, 22.9% incorporated baked before unbaked egg. Sensitization did not delay tolerance but was linked to a higher risk of immediate hypersensitivity during reintroduction. IgE-mediated symptoms were evident during reintroductions in sensitized patients but were absent in non-sensitized and untested patients. The overall phenotype switch rate from FPIES to IgE food allergy was at least 9.2%. Concomitant IgE-mediated food allergy to other foods was more common among sensitized patients.

Conclusions: Our data suggest that testing for allergic sensitization to egg may help stratify patients with FPIES at risk for future IgE-mediated symptoms. Future prospective studies should evaluate the optimal timing and predictive value of skin testing in patients with FPIES and the utility of introducing baked egg in patients with egg FPIES.

Keywords: Allergic sensitization; Atypical FPIES; Baked egg tolerance; Egg allergy; Egg hypersensitivity; Food protein–induced enterocolitis syndrome; IgE-mediated food allergy.

Figure 1.. Overview of FPIES patient record identification.

Patients with FPIES to egg were identified using ICD codes, and the FPIES history was verified. Thirteen patients had an unclear history of FPIES, but three were confirmed to have FPIES through diagnostic oral food challenges with unbaked egg. Of the 153 patients included in the review, 124 (81%) underwent skin prick testing (SPT), although the timing varied among patients. Patients were classified as sensitized if they had a positive SPT result (> 3 mm above control). Abbreviations: Food protein-induced enterocolitis syndrome (FPIES)

Figure 2.

Impact of Egg Sensitization on Tolerance and Reaction Risk in FPIES. (A) The time interval for each patient is displayed, with the box representing the interquartile range and the median indicated along with whiskers representing the minimum and maximum values. (B) The age at the time of egg reintroduction in months is presented for each patient, with brackets showing the median and interquartile range. Kaplan Meier analysis of egg reintroduction tolerance was conducted for FPIES patients who did not display IgE symptoms, with (C) baked egg (N=42 patients, P = 0.338) and (D) unbaked egg reintroduction (n = 52, P = 0.2848), indicating no difference in the time to tolerance based on sensitization status. Abbreviations: Sensitized (S), Non-sensitized (N), Untested (U).