1 Hospital Santa Maria - CHLN, Centro Hospitalar Lisboa Norte, Immunoallergology, Lisbon, Portugal,
2 Hospital Dona Estefânia – Centro Hospitalar Lisboa Central, Immunoallergology, Lisbon, Portugal,
3 CEDOC, Faculdade de Ciências Médicas, FCM, Universidade Nova de Lisboa, Lisbon, Portugal,
4 Hospital de Dona Estefânia, Centro Hospitalar de Lisboa Central, Clinical Pathology, Lisbon, Portugal
XXXII Reunião anual da EAACI. Milão, Junho de 2013
Background: Egg allergy is the second most frequent food allergy in children, being the egg white responsible for more severe reactions than yolk. As for other foods, the diagnosis is based on clinical history, skin prick tests and determination of specific IgE (sIgE). Ultimately, an oral food challenge (OFC) is needed to confirm either allergy or tolerance.
Aim: To determine the best threshold value for heated egg white sIgE associated with clinical tolerance.
Methods: All children submitted to heated egg white OFC from January 2010 to December 2012, for which specific IgE to egg white was determined in the 12 months prior to the OFC were included. ROC curves were calculated to determine the sensitivity (SE) and specificity (SP) of egg white specific IgE levels versus the OFC outcomes. IgE determination was performed using ImmunoCAP.
Results: A total of 48 children (60% males) were enrolled. Thirty tree children had a previous clinical reaction to egg and for the remaining fifteen avoidance was recommended due to positive skin prick test and high sIgE for egg white. Most reactions were cutaneous (urticaria/angioedema - 62%; eczema exacerbation - 14%) and gastrointestinal symptoms (17%). Two patients had anaphylaxis. The median age of the first symptoms was 1.0 year (P25 - P75: 0.7 - 1.1 years) and OFC were performed at a median age of 3 years (P25 - P75: 2 - 5 years). The determination of egg white specific IgE levels was moderatly useful in discrimination cases at risk for heated egg white allergy (AUC: 0.70). The best decision threshold for egg white specific IgE was 5.63 KU/L (sensitivity: 55.6%; specificity: 89.7%).
Conclusion: Our results differ from others previously reported to egg. Despite its limitations, egg white sIgE was a useful tool. The specific IgE threshold achieved could suggest heated egg white allergy. Although it doesn't replace OFC which still remains the gold-standard for food allergy diagnosis.
Keywords: egg white, specific IgE, egg allergy