Validity of specific IgE antibodies in children with egg allergy

Background The demonstration of specific IgE antibodies to egg supports the existence of allergy to this food, but a correct diagnosis can only be obt ained after a challenge test. Several studies have assessed different cut-o ff points in the level of these antibodies as predictors of clinical reacti vity. Objective Validation of the specific IgE antibodies measured by the CAP Sys tem Fluorescence enzyme immunoassay (FEIA) technique in the diagnosis of eg g allergy in children under 2 years of age. Methods A prospective study of 81 children with suspected egg allergy was p erformed. Specific IgE antibodies was quantified for egg white, egg yolk, o voalbumin and ovomucoid. The diagnostic challenge test was carried out foll owing the previously established criteria. The validity of the specific IgE antibodies was analysed using children with a negative diagnostic challeng e test as control group. Results The prevalence of egg allergy in the group studied was 79% and egg white was the allergen that showed the greatest diagnostic efficacy. The se nsitivity and positive predictive value of the prick test and of the CAP to egg white were excellent and the specificity and the negative predictive v alue had lower values. A level of less than or equal to0.35 KUA/L for speci fic IgE antibodies to egg white predicted the existence of reaction in 94% of the cases. Conclusions Quantification of the specific IgE antibodies to eg white is us eful in the diagnosis of egg allergy. In children under 2 years of age with a background of immediate hypersensitivity after egg ingestion and presenc e of specific IgE antibodies to egg white of less than or equal to0.35 KUA/ L, diagnostic challenge test is not necessary to establish the diagnosis of allergy to this food.