Purpose: The purpose of this study was to evaluate the utility of specific IgE (sIgE) concentrations for the diagnosis of immediate-type egg and cow's milk (CM) allergies in Korean children and to determine the optimal cutoff levels.
Methods: In this prospective study, children ≥12 months of age with suspected egg or CM allergy were enrolled. Food allergy was diagnosed by an open oral food challenge (OFC) or through the presence of a convincing history after ingestion of egg or CM. The cutoff levels of sIgE for egg white (EW) and CM were determined by analyzing the receiver operating characteristic curves.
Results: Out of 273 children, 52 (19.0%) were confirmed to have egg allergy. CM allergy was found in 52 (23.1%) of 225 children. The EW-sIgE concentration indicating a positive predictive value (PPV) of >90% was 28.1 kU/L in children <24 months of age and 22.9 kU/L in those ≥24 months of age. For CM-sIgE, the concentration of 31.4 kU/L in children <24 months of age and 10.1 kU/L in those ≥24 months of age indicated a >90% PPV. EW-sIgE levels of 3.45 kU/L presented a negative predictive value (NPV) of 93.6% in children <24 months of age, while 1.80 kU/L in those ≥24 months of age presented a NPV of 99.2%. The CM-sIgE levels of 0.59 kU/L in children <24 months of age and 0.94 kU/L in those ≥24 months of age showed NPVs of 100% and 96.9%.
Conclusions: Our results indicate that different diagnostic decision points (DDPs) of sIgE levels should be used for the diagnosis of egg or CM allergy in Korean children. The data also suggest that DDPs with high PPV and high NPV are useful for determining whether OFC is required in children with suspected egg or CM allergy.
Keywords: Egg allergy; food allergy; milk allergy; specific IgE.