Reduction Rate of Specific IgE Level as a Predictor of Persistent Egg Allergy in Children

Egg is the most common food allergen in infants. However, the natural course of egg allergy has not been fully elucidated. This study aimed to describe clinical characteristics and to identify prognostic factors associated with tolerance acquisition of immunoglobulin E (IgE)-mediated egg allergy in children.

Children who underwent more than 1 follow-up egg white-specific immunoglobulin E (EWsIgE) test between November 2005 and November 2015 at -Severance Children's Hospital were assessed. Children were diagnosed as having IgE-mediated egg allergy based on immediate allergic reaction after egg consumption and an EWsIgE level of > 0.35 kU/L. The children were divided into "tolerant" and "persistent" groups according to tolerance acquisition defined as egg consumption without adverse allergic reactions.

Of 124 participants, egg allergy resolved in 101 (81.5%) children. The persistent group had more atopic dermatitis (P = 0.039), and more wheat (P = 0.009) and peanut (P = 0.012) allergies compared to the tolerant group. The EWsIgE levels at diagnosis (EWsIgE_diag) were higher in the persistent group than in the tolerant group (P = 0.001). The trend of the EWsIgE levels in the tolerant group decreased markedly over time compared to the persistent group (P < 0.001). In predicting egg allergy tolerance acquisition, the reduction rate of EWsIgE level after 12 months from diagnosis (ΔEWsIgE_12mo) tended to be more accurate than EWsIgE_diag (area under the curve: 0.835 vs. 0.731). When ΔEWsIgE_12mo was ≥ 30%, tolerance acquisition was more frequent than that of < 30% (91.9% vs. 57.9%; P < 0.001).

ΔEWsIgE_12mo can be used as an early independent predictor of tolerance acquisition of IgE-mediated egg allergy in children.