797:
Temporal Trends of Food Specific IgE Levels During and After Anaphylaxis
Monday, March 5, 2018
South Hall A2 (Convention Center)
Alexandra Langlois, MD, Sofianne Gabrielli, MSc, Ann Elaine Clarke, MD, MSc, Sarah De Schryver, MD, Greg Shand, BSc, MSc, Moshe Ben-Shoshan, MD, MSc
RATIONALE: Little is known about the dynamics of specific IgE antibody (SpIgE) levels during and after anaphylactic reactions. We aimed to evaluate changes in food SpIgE levels during and after food-induced anaphylaxis.

METHODS: As part of the Cross Canada Anaphylaxis REgistry (CCARE), between 2013 and 2017, SpIgE levels were drawn within 2 hours of presentation with food-induced anaphylaxis to the emergency department of the Montreal Children’s Hospital and at least 2 weeks later. All SpIgE levels were measured using Phadia ImmunoCAP. Changes in levels were assessed with the paired Wilcoxon test.

RESULTS: Among 34 cases, the mean age was 3.9 years and 59% were males. The main culprits were egg, tree-nut and peanut. The reaction was severe in 6% of cases. The mean culprit SpIgE was 15.12 kUA/L (SD: 27.26) during the anaphylactic reaction. When repeated at follow up, the mean SpIgE increased to 21.56 kUA/L (SD: 33.31). This resulted in a difference of 6.44 kUA/L (0.57, 12.31), p = 0.003). The mean time interval between anaphylaxis and post-reaction SpIgE was 12 weeks (SD: 24.97). There was no substantial difference in SpIgE levels of an unrelated food (difference of 0.055 kUA/L (-1.32, 1.21), p = 0.66).

CONCLUSIONS: Establishing the dynamics of SpIgE levels is crucial for appropriate use of confirmatory tests to identify anaphylaxis triggers. Our results indicate that SpIgE levels to culprit foods are lower during anaphylaxis. Further, our results suggest that changes in SpIgE levels may contribute to identification of the appropriate culprit food when history is unclear.