Predicting Outcomes of Oral Food Challenges by Using the Allergen-specific IgE/Total IgE Ratio

Although allergists typically use allergen-specific IgE (sIgE) levels or skin prick test wheal sizes to identify food allergens that may provoke IgE-mediated food-induced allergic reactions, both tests have high rates of false positivity and mislabel patients who are tolerant as allergic to the food allergen.  We conducted a retrospective chart review to examine the accuracy of the ratio of sIgE to total IgE ("Ratio") in predicting the outcome of challenges performed to confirm the development of tolerance. Interestingly, we found that the Ratio for participants who failed their challenge was higher than the Ratio of those who passed their challenge (failed 1.48% vs passed 0.49%; n = 195) and that the ratio was a stronger predictor of OFC outcome than sIgE alone. These trends were mostly associated with more persistent food allergens, such as peanut, tree nuts, shellfish, and seeds (failed 2.18% vs passed 0.41%; n = 93) (Ratio 0.81 vs sIgE alone 0.54; P < .01). CONCLUSION: Our findings suggest that the Ratio is more accurate than sIgE alone in predicting outcomes of challenges performed to confirm the development of tolerance to select food allergens, especially to peanut and tree nuts. The Ratio may be useful in identifying patients most likely to pass oral food challenge.  CLICK HERE for more details.