PURPOSE OF THE STUDY.
To determine the association between skin prick test (SPT) and specific immunoglobulin (Ig)E to egg proteins with oral food challenge outcomes.
One hundred fifty-four infants aged 1 to 18 months with cow’s milk allergy and/or atopic dermatitis who had never ingested egg were recruited from the Pediatric Allergy and Clinical Immunology Department, Sant Joan de Deu Hospital, in Barcelona, Spain, from October 2010 to October 2011.
SPT to egg proteins including egg white, egg yolk, ovalbumin, and ovomucoid were performed for each patient. If SPT was positive, serum IgE (sIgE) to egg proteins were measured. Patients who were sensitized to egg by SPT or sIgE underwent a single-blind challenge with egg yolk, egg white, and raw egg between 12 and 18 months of age. Food challenge outcome was correlated with SPT and sIgE to determine cutoff points with the best diagnostic accuracy.
Ninety-four patients were sensitized to egg and were challenged to egg in the hospital. Of these, 27 (28.7%) tolerated both cooked and raw egg, and 65 (69.2%) tolerated only cooked egg. The remaining 60 who were non–egg sensitized were instructed to introduce egg at home. Of these, 59 tolerated home introduction of egg. In egg allergic patients, egg white SPT and ovalbumin sIgE had the best area under the curve. High positive predictive values were obtained for egg white SPT and egg white sIgE.
Sensitized infants with egg white SPT ≥8 mm and/or egg white sIgE ≥8.36 kU/L had high probability of having a positive oral food challenge. For cooked egg allergy, a negative predictive value of 92.8% was found for ovomucoid SPT of 3.5 mm and 94.3% for sIgE of 0.8 kU/L. Notably, the sensitivity and negative predictive values were low for egg white SPT and sIgE, with some patients being symptomatic with egg ingestion despite having low or negative values.
This study found that in children <18 months of age, more than half of patients with cow’s milk allergy and atopic dermatitis without previous egg consumption are also sensitized to egg, and >60% of those sensitized have allergic reactions to egg. The majority of the sensitized patients in this study were reactive to raw egg only. The results of this study suggest that egg white SPT and/or sIgE testing are useful to assess likelihood of egg allergy and risk stratify when considering food challenges in this population.
- Copyright © 2015 by the American Academy of Pediatrics