Clinical and laboratory factors associated with negative oral food challenges

Children with food-specific IgE (FSIgE) ≤2 kUa/L to milk, egg, or peanut (or ≤5kUa/L to peanut without history of previous reaction) are appropriate candidates for oral food challenge (OFC) to investigate resolution of food allergy, because these FSIgE cutoffs are associated with ∼50% likelihood of negative OFC. This study was designed to identify characteristics of children undergoing OFC, based on these FSIgE levels, who are most likely to show negative OFC. We collected demographics, severity of previous reaction, history of atopic diseases, total IgE and FSIgE values, and skin tests results on children who underwent OFCs to milk, egg, or peanut, based on the recommended FSIgE cutoffs. We identified independent factors associated with negative OFCs. Four hundred forty-four OFCs met our inclusion criteria. The proportions of negative OFCs performed based on FSIgE cutoffs alone were 58, 42, and 63% to milk, egg, and peanuts, respectively. Regression models identified independent factors associated with negative OFCs: lower FSIgE levels (all three foods), higher total IgE (milk), consumption of baked egg products (egg), and non-Caucasian race (eggs and peanuts). Combinations of these factors identified subgroups of children with proportions of negative OFCs of 83, 75, and 75% for milk, eggs, and peanuts, respectively. Combinations of clinical and laboratory elements, together with FSIgE values, might identify more children who are likely to have negative OFCs compared with current recommendations using FSIgE values alone. Once validated in a different population, these factors might be used for selection of patients who are most likely to show negative OFCs.