Is it possible to make a diagnosis of raw, heated, and baked egg allergy in children using cutoffs? A systematic review

The diagnosis of IgE-mediated egg allergy lies both on a compatible clinical history and on the results of skin prick tests (SPTs) and IgEs levels. Both tests have good sensitivity but low specificity. For this reason, oral food challenge (OFC) is the ultimate gold standard for the diagnosis. The aim of this study was to systematically review the literature in order to identify, analyze, and synthesize the predictive value of SPT and specific IgEs both to egg white and to main egg allergens and to review the cutoffs suggested in the literature. A total of 37 articles were included in this systematic review. Studies were grouped according to the degree of cooking of the egg used for OFC, age, and type of allergen used to perform the allergy workup. In children <2years, raw egg allergy seems very likely when SPTs with egg white extract are 4mm or specific IgEs are 1.7 kU(A)/l. In children 2years, OFC could be avoided when SPTs with egg white extract are 10mm or prick by prick with egg white is 14mm or specific IgE is 7.3 kU(A)/l. Likewise, heated egg allergy can be diagnosed if SPTs with egg white extract are >5 and >11mm in children <2 and 2years, respectively. Further and better-designed studies are needed to determine the remaining diagnostic cutoff of specific IgE and SPT for heated and baked egg allergy.