CRACKING THE EGG: PREDICTORS OF BAKED EGG ORAL FOOD CHALLENGE OUTCOMES

Introduction Approximately 70% of egg allergic patients can tolerate the allergen in its baked form. Previous studies suggest an egg-specific IgE ≤2.5 kU/L predicts a 50% negative decision point for baked egg oral food challenges (OFCs). However, there are limited studies regarding the value of skin prick tests (SPTs) in predicting baked egg OFCs. The objective of this study is to identify the differences between baked egg-reactive and tolerant patients in order to improve the negative predictive value of baked egg OFCs. Methods We conducted a retrospective medical chart review of egg allergic pediatric patients, 1-18 years of age, who underwent a baked egg OFC. Results 63 baked egg OFCs were performed, of which 45 patients (71%) passed. We attempted to identify clinical and immunologic predictors of baked egg-tolerant patients. An older age at the time of challenge achieved a significant predictive value ( p 0.04). Baked egg-tolerant patients had a smaller mean SPT wheal size compared to baked egg-reactive patients (6.69 mm vs 10.43 mm respectively, p 0.01) and a lower median egg white-specific IgE level (1.7 kU/L vs 3.04 kU/L respectively, p 0.2). Twelve of eighteen patients (92%) with a mean SPT wheal size ≤7 mm and an egg-specific IgE ≤5 kU/L were baked egg-tolerant ( p 0.02). Conclusions SPT wheal size coupled with egg-specific IgE achieved a sufficiently high predictive value. Therefore, we recommend obtaining both when evaluating egg allergic patients.