Ara h 2 is the best predictor for peanut allergy in adults

Background: Specific IgE (sIgE) to Ara h 2 as a clinical predictor for peanut allergy in children has a diagnostic value comparable with a prediction model that contains sex, skin prick test (SPT), sIgE to peanut extract, and total IgE minus sIgE. In adults, the diagnostic value of peanut components has not yet been studied. Objective: To validate a pediatric prediction model in an adult population; to define the diagnostic value of sIgE to peanut components. Methods: Validation was performed by discrimination with an area under the receiver operating characteristic curve (AUC) and calibration with the Hosmer-Lemeshow test. The diagnostic value of the peanut components was assessed with the AUC. Results: Validation of the pediatric model in 94 adults showed poor discrimination (AUC, 0.64) but good calibration (P= .48); sIgE to Ara h 2 was the best diagnostic predictor (AUC, 0.76). Byusing a cutoff value with a 100% positive predictive value (≥1.75 kU/L), 28% of patients could be diagnosed with 100% accuracy. The highest negative predictive value was 63%. A higher negative predictive value could not be calculated for any other test. Although sIgE to Ara h 2 was significantly correlated with severity, it did not discriminate between mild and severe allergy in individual patients (AUC < 0.65). Conclusion: sIgE to Ara h 2 has the best discriminative ability of all diagnostic tests. It can accurately diagnose peanut allergy in 28% of patients but cannot be used to exclude a peanut allergy in an adult population. © 2013 American Academy of Allergy, Asthma & Immunology.