Establishing a cut-off for the serum levels of specific IgE to milk and its components for cow's milk allergy: Results from a specific population

Background: Cow's milk allergy diagnosis many times requires double-blind placebo-controlled food challenge (DBPCFC), which presents high accuracy but involves risks, specifically in infants and anaphylactic patients. The identification of the cut-off values for specific IgE to milk or its components would contribute to cow's milk allergy (CMA) diagnosis. The aim of this study was to compare discriminating concentration of a cow's milk specific IgE and its fractions (alpha-lactoalbumin, beta-lactoglobulin, casein) in children for the CMA diagnosis. Methods: this study included 123 patients (M:F= 1.3:1) median age at diagnosis = 1.91 years, (3.5 m to 13.21 y) with CMA diagnosis via DBPCFC (n = 26), proven anaphylaxis due to cow's milk (n = 46) or a suggestive clinical history associated with a positive skin prick test (n = 51) and open oral food challenge. The control group included 61 patients (1 male: 1.1 female) ages ranging from 0.66 to 16.7 years (median = 6.83 years). Receiver operator characteristics (ROC) curves were constructed to determine the best cut-offs that guarantees high specificity (>95%) for cow's milk and its components. Results: considering 98% specificity, cut-off points were: 3.06 kU/L for cow's milk, 2.06 kU/L for a-lactalbumin, 1.85 kU/L for beta-lactoglobulin and 1.47 kU/L for casein. The best ROC curve (area under the curve = 0.929) was obtained evaluating cow's milk. Conclusion: this study showed that the cut-off point detected for whole cow's milk revealed a better discriminatory capacity for CMA diagnosis without the necessity of the milk components testing. (C) 2013 SEICAP Published by Elsevier Espana, S.L.U. All rights reserved.