Blood or skin: What is best in predicting cow’s milk allergy diagnosis?

Abstract

Cut-off values for both skin prick tests (SPT) and specific IgE (sIgE) levels for predicting cow´s milk allergy (CMA) diagnosis are not universally defined. This study is a retrospective analysis of consecutive children (0-18 years-old) with suspected CMA tested with SPT and sIgE for cow’s milk (CM) and its fractions between 2016-2017. CMA diagnosis was defined by a positive oral food challenge or a highly suggestive clinical history of CMA and SPT and/or sIgE positive to CM and/or its fractions. One hundred and five patients were included, 58% males with a median age of 2.5 (P25-P75:1-6) years and the diagnosis was confirmed in 83 patients (79%). The variables associated with CMA diagnosis were SPT with CM (p<0,05) and casein (p<0,05) and all sIgE to CM and its fractions (α-Lactalbumin, β-Lactoglobulin and casein; p<0,05 for all). Optimal cut-off points (Youden’s index) for CMA diagnosis were 4.5mm for the mean wheal diameter to Cow’s milk and 3mm to casein. For sIgE levels the optimal cut-off points were: were: CM 4.36 KUA/L, alfa-lactalmunin 1.6 KUA/L, b-lactoglobulin 1.7 KUA/L and casein 2.6KUA/L. The role of SPT and sIgE levels to cow’s milk and its fractions is unequivocal in CMA follow-up. Moreover, sIgE levels seem to be more discriminatory than SPT.