Differential diagnosis of IgE-mediated allergy in young children with wheezing or eczema symptoms using a single blood test

Background: Allergy-like symptoms are common in young children, but the case history and physical examination cannot identify the underlying origins of overlapping symptom profiles. Objective: To evaluate a blood test, Phadiatop Infant (Pharmacia Diagnostics AB, Uppsala, Sweden), for differentiating the capability of IgE-mediated disease in young children with recurrent wheezing, eczema, or both. Methods: One hundred forty-seven children (mean age, 2.0 years) were consecutively referred to 2 allergy centers by their primary care physician for recurrent wheezing, eczema, or both. The allergist's clinical evaluation included medical history, physical examination, skin prick testing with inhalant and food allergens, and specific IgE determinations in blood. The accuracy of Phadiatop Infant was evaluated in a masked manner against the allergist's final diagnosis. Results: Sixty-nine children had wheezing, 69 had eczema, and 9 had both symptoms. Sixty-one children were clinically diagnosed as having IgE-mediated allergy, 78 as having non-IgE-associated disease, and 8 as having an inconclusive diagnosis. Fifty-six of the 61 children with IgE-mediated allergy had positive Phadiatop Infant test results, and 64 of 78 without the condition had negative results. Sensitivity was 92% and specificity was 82%, with positive and negative predictive values of 80% and 93%, respectively. Thirteen children with a positive Phadiatop Infant test result and a negative final diagnosis were retested after 2 years; 12 of them were diagnosed as having IgE-mediated allergy using a masked evaluation. Conclusions: The Phadiatop Infant blood test discriminates between IgE- and non-IgE-mediated symptoms in children younger than 4 years.