High albumin sensitization drives uninterpretable basophil activation tests in cow’s milk allergy

OBJECTIVES: The basophil activation test (BAT) is increasingly used for diagnosing IgE-mediated food allergies, yet its performance in cow's milk allergy (CMA) remain insufficiently characterized in real-world pediatric practice. This study evaluates the diagnostic accuracy of BAT for CMA and identifies factors associated with non-interpretable results. METHODS: We carried out a single-center retrospective observational study in 59 children with a documented history of cow's milk reactions. Clinical status at the time of BAT was determined using oral food challenges (OFCs), skin prick tests, and specific IgE (sIgE) levels. ROC analyses were conducted to assess the diagnostic performance of BAT parameters and sIgE levels. RESULTS: /L predicted BAT failure with 100 % PPV. CONCLUSIONS: BAT has high diagnostic accuracy for CMA when interpretable but is frequently limited by spontaneous activation in highly sensitized children. sIgE thresholds - particularly BSA-sIgE - may help identify patients in whom BAT can be reliably used, supporting more targeted integration of BAT into clinical practice.