D2.291 - Trends and Patterns Observed Among Suspected Egg-allergic Children in Hong Kong: A 26-year Retrospective Study

According to the European Academy of Allergy and Clinical Immunology (EAACI) diagnostic algorithm (2023), food allergy can be confirmed in patients with convincing clinical history and positive food-specific skin prick test (SPT) (i.e., ≥ 3 millimeters) or serum immunoglobulin E (sIgE) (i.e., ≥ 0.35 kU/L). The clinicodemographic profiles of “confirmed egg-allergic” (CEA) patients deemed solely by history and sensitization, but not oral food challenge, remain unknown. We aimed to describe CEA patients' clinical features and sensitization patterns, then compare them with those of other suspected egg-allergic children.

Children (aged < 18 years) with suspected egg allergy who presented from 1999 to 2024 at a university-affiliated pediatric unit in Hong Kong were included. Categorical and continuous variables were analyzed by Fisher’s exact test and Mann-Whitney U test. Inter-subgroup SPT wheal diameters were compared with Kruskal-Wallis test and Dunn’s multiple comparisons post hoc test.

Two hundred and fifty-eight (56.0%) out of 461 included patients were deemed “probably egg-allergic” (PEA) by history, in which 182 were CEA, while the remaining 203 were “unlikely egg-allergic” (UEA). Subjects in the CEA subgroup were younger at first visit than PEA-not-CEA subjects (P < .001), but comparable with UEA subjects (P = .142). Over 60% of subjects in the CEA, PEA-not-CEA and UEA subgroups had comorbid eczema. Well-cooked eggs were the predominant food trigger for all subgroups and the differential allergenicity of preceding triggers did not correlate with the severity of allergic reactions (i.e., any anaphylaxis). Consumption of local delicacies — steamed egg and egg tarts — were identified as preceding triggers, as was the cultural practice of placing hard-boiled eggs onto children’s forehead after minor head injury to alleviate bruising (causing direct skin contact with egg). Meanwhile, egg-containing snacks popular in Western countries (e.g., muffins) were not reported as triggers, perhaps due to relatively rare consumption in our locality. In terms of clinical manifestation, localized and generalized non-urticarial rash were associated with UEA status (both P < .001); dyspnea correlated significantly with PEA or CEA statuses (both P < .001), while drowsiness correlated with CEA status as opposed to UEA (P = .030).

Both PEA and CEA subgroups exhibited distinct symptomatology from UEA children. Confirmed egg-allergic children presented earlier and showed significantly greater SPT wheal diameters than PEA and UEA subjects.

(This abstract was partly supported by the Hong Kong Institute of Allergy research grant.)