Scientific Study

BACKGROUND: Current diagnostic testing methods for peanut allergy, including serum specific immunoglobulin E (sIgE) and skin-prick testing (SPT), have low specificity, whereas oral food challenge (OFC) carries significant risk of provoking adverse events. Mucosal brush biopsy (MBB) from the oral cavity is currently being studied as a new diagnostic test for peanut allergy, but normative data is not yet available with which to begin measuring specificity and predictive value. METHODS: Twenty individuals with no history of adverse reactions from eating peanuts underwent oral MBB and serum testing for peanut sIgE. These data were then compared with previously published data from 10 individuals with a history of clinical peanut allergy, in order to generate receiver operating characteristic (ROC) curves and calculate the sensitivity, specificity, and positive and negative predictive values for both testing modalities. RESULTS: The optimal cutoff levels for oral MBB and sIgE testing were 0.12 kU/L and 1.0 kU/L, respectively. At 0.12 kU/L, the sensitivity of oral MBB testing was 80% and the specificity was 85%, whereas at 1.0 kU/L, the sensitivity of sIgE testing was 50% and the specificity was 100%. From the ROC curves, the areas under the ROC curve (AUC) for oral MBB and sIgE were 0.91 (p < 0.001) and 0.74 (p = 0.007), respectively. Combination testing further increased both sensitivity and accuracy over oral MBB alone. CONCLUSION: In this pilot study, oral MBB demonstrated high sensitivity and specificity for screening individuals with and without oral cavity clinical reactivity to peanuts and may represent a potentially useful testing method for the diagnosis of peanut allergy in the future.