New paper: 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. 
Therefore we decided to carry out a study to examine the accuracy of the ratio of sIgE to total IgE in predicting the outcome of challenges performed to confirm the development of tolerance. 

To conduct the study we reviewed the medical records of children diagnosed with food allergy who participated in oral food challenge at an allergy outpatient clinic (2009-2013).  Based on our analysis, we determined 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).  We also found that the Ratio was significantly more accurate than sIgE alone in predicting challenge outcome (Ratio 0.69 vs sIgE alone 0.55; P = .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 alone 0.54; P < .01). 

Therefore, based on our findings we concluded that the Ratio may in fact be more accurate than sIgE alone in predicting which patients are likely to pass an oral food challenge, particularly for patients with a suspected peanut or tree nut allergy.