Retrospective analysis of 222 oral food challenges with a single dose in acute food protein-induced enterocolitis syndrome

Background: The method of performing oral food challenge (OFC) in acute food protein–induced enterocolitis syndrome (FPIES) has not been systematically studied. Therefore, there is a certain variability in the choice of the various centers. Methods: Since 2011, we have been performing OFC for acute FPIES with a single dose of culprit food, a full serving size for age. In case of atypical FPIES (skin prick test, SPT, positive), we applied this protocol only if the description of previous adverse reactions was compatible with that of a classic acute FPIES, if other IgE-mediated food allergies were absent, and if the mean diameter of the wheal evoked by the SPT with the challenged food was ≤5 mm. We have retrospectively analyzed 222 OFCs from 2011 to 2020. The grading of reactions was carried out according to the International Consensus Guidelines on FPIES of 2017. Results: Forty-eight of 222 OFC (21.6%) failed. The mild reactions were 22 of 48 (45.8%), the moderate ones 22 of 48 (45.8%), and the severe ones 4 of 48 (8.4%) failed OFCs. The tested food processing (in the case of cow milk and chicken egg) did affect neither probability nor severity of the reaction. Patients with positive SPT for the tested food presented four times more severe reactions (2 of 9 failed OFC, 22.2%) than patients with negative SPT (2 of 39 failed OFC, 5.1%) (P =.316). Conclusions: The administration of a single dose in a full serving size for age appears to be a sufficiently safe method for OFC for acute FPIES, with the benefit of saving time. In patients with positive SPT for the tested food, it may be prudent to start with a smaller dose carrying on, in the absence of adverse reactions, with the administration of the full dose after a 4-hour observation.