Discordance between aeroallergen specific serum IgE and skin testing in children younger than 4 years

Background: Atopic sensitization to aeroallergens in early life has been found to be a strong risk factor for the development of persisting asthma in young children with recurrent wheeze. Objective: To assess the yield of skin prick test (SPT) compared with allergen specific serum IgE (sIgE) testing at identifying aeroallergen sensitization in atopic children younger than 4 years. Methods: Concordance between SPT and allergen-specific sIgE testing for 7 common aeroallergens was analyzed in 40 atopic inner-city children 18 to 48 months of age (mean [SD], 36 [9] months) with recurrent wheezing and family history of asthma and/or eczema. Results: In 80% of children one or more allergen sensitizations would have been missed if only SPT had been performed, and in 38% of children one or more sensitizations would have been missed if only sIgE testing had been performed. Agreement between the SPT and sIgE test was fair for most allergens (κ = -0.04 to 0.50), as was correlation between sIgE levels and SPT grade (ρ = 0.21 to 0.55). Children with high total sIgE (≥300 kU/L) were more likely to have positive sIgE test results, with negative corresponding SPT results (P =.02). Conclusion: Our study revealed a significant discordance between allergen-specific SPT and sIgE testing results for common aeroallergens, suggesting that both SPT and sIgE testing should be performed when diagnosing allergic sensitization in young children at high risk of asthma.