Rationale: Although allergists typically use allergen-specific Immunoglobulin E (IgE) 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 sought to examine the accuracy of the ratio of allergen-specific IgE to total IgE (“Ratio”) in predicting the outcome of challenges performed to confirm the development of tolerance.
Methods: Medical records of food allergy patients participating in an oral food challenge at an allergy outpatient clinic were reviewed for IgE serology and oral food challenge data, which were analyzed for associations using logistic regressions and Receiver Operator Characteristics curves.
Results: 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). ROC curves showed the Ratio was significantly more accurate than allergen-specific IgE alone in predicting challenge outcome (Ratio=0.69 vs. sIgE=0.55, P=0.03). 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=0.54, P<0.01).
Conclusion: The Ratio is more accurate than allergen-specific IgE 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 an oral food challenge.