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

BACKGROUND: 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 the present paper is 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 main egg allergens and to review the cut-offs suggested in the literature. METHODS: A total of 37 articles were included in this systematic review. Studies were grouped according to degree of cooking of the egg used for OFC, age and type of allergen used to perform the allergy work-up. RESULTS: In children < 2 years, raw egg allergy seems very likely when SPTs with egg white extract are >= 4 mm or specific IgEs are >= 1.7 kUA /L. In children >= 2 years, OFC could be avoided when SPTs with egg white extract are >=10 mm or Prick by Prick with egg white are >=14 mm or specific IgE are >= 7.3 kUA /L. Likewise, heated egg allergy can be diagnosed if SPTs with egg white extract are > 5 mm and > 11 mm in children < 2 years and >= 2 years, respectively. CONCLUSIONS: Further and better-designed studies are needed to determine the remaining diagnostic cut-off of specific IgE and SPT for heated and baked egg allergy.