Safety and feasibility of heated egg yolk challenge for children with egg allergies

Background: Hen's egg allergy is a frequent cause of childhood food allergy. Egg yolk is used in various commonly consumed foods; if children with allergy to hen's egg could eat heated egg yolk, their quality of life (QOL) would improve. No reports exist regarding oral food challenges (OFCs) for heated egg yolk. We aimed to clarify whether pediatric patients allergic to hen's egg could consume heated egg yolk. Methods: Data from pediatric patients who had undergone OFCs for heated egg yolk were evaluated retrospectively. Results: Among 919 patients, positive OFC results were obtained in 17.0% of patients; seven presented with severe symptoms. Older age, high specific IgEvalue for ovomucoid, low total IgE levels, and history of anaphylaxis related to food other than hen's egg were risk factors for positive OFC results. Specific IgE values for eggwhite, ovomucoid, and egg yolk, indicative of a negative predictive value > 95%, were 0.71, 0.41, and 0.17 kU(A)/l, respectively. Aspecific IgE to ovomucoidlevels of 100 kU(A)/l predictedheated egg yolk-positive OFCs for 38.3% of patients. Among 763 patients with a negative OFC, seven (0.9%) reacted to heated egg yolk at home, and 756 (99.1%) consumed hen's egg yolk safely. Conclusions: Most pediatric patients allergic to heated hen's egg safely consumed heated egg yolk. Heated egg yolk OFCs rarely provoked severe symptoms and may be recommended for improving the QOL of children with allergy to hen's egg.