Diagnostic utility of skin prick test to cooked egg in children with egg allergy

ABSTRACT

PURPOSE: Reliable predictors of tolerance to cooked egg in an egg allergic population are not established. We investigated the usefulness of the skin prick test to cooked egg in children with egg allergy. METHODS: We studied 36 children with egg allergy. Skin prick tests (SPTs) for the uncooked or cooked form of egg white and egg yolk, whole egg, ovomucoid (OVM), and ovalbumin (OVA) were performed at diagnosis. The reagents of cooked egg for SPT were prepared by baking for 25 minutes in 200 degree oven. We also examined specific IgE levels to whole egg, egg white, egg yolk, OVM, and OVA. RESULTS: Patients with history of allergic reaction to extensively heated egg showed significantly increased wheal size for cooked egg white (median [interquartile range]), 10.5 [7.0-14.6] vs. 4.2 [0.0-5.6], P<0.001) and OVM (9.6 [7.3-13.8] vs. 5.6 [0.0-7.8], P=0.001) than those without the history. The strongest positive correlation was found between wheal size for cooked egg white and OVM (r=0.788, P<0.001). SPT wheal size for cooked egg white were positively correlated with serum OVM-specific IgE levels (r=0.691, P<0.001). Cutoff value was 7.0 mm in SPT wheal size for cooked egg white, the sensitivity was 73.1% and specificity was 99.0%. SPT for cooked egg white showed significantly higher area under curve than serum egg white specific IgE. CONCLUSION: Our results suggest that SPT to cooked egg white may be useful predictor of allergic reaction to cooked egg. Further investigations will be needed.