Predictors of initial oral food challenge outcome in food protein-induced enterocolitis syndrome

Background: There is a paucity of data on predictors of clinical history in oral food challenge (OFC) outcome for the initial diagnosis of food protein-induced enterocolitis syndrome (FPIES). Objective: This study aimed to identify predictors for the diagnosis of FPIES. Methods: The study included patients who underwent OFC to diagnose FPIES from 2010 to 2021. Patients with a positive OFC result were classified as belonging to the FPIES group, and those with negative OFC result within 120 days from the last symptomatic episode were classified as belonging to the no-allergy (NA) group. Background factors were analyzed in the groups. Results: A total of 50 OFCs to 12 different foods were conducted in 50 patients. Of those 50 patients, 30 were classified as belonging to the FPIES group. No significant difference was observed between the FPIES and NA groups with respect to background factors, including the features of symptomatic episodes and examinations of immediate-type allergy. A history of asymptomatic ingestion was observed in 23 of 24 and 13 of 19 patients in the FPIES and NA groups, respectively; thus, it was significantly more common in patients with FPIES. The diagnostic rate of patients with fewer than 3 symptomatic episodes was 52%, and that of patients with 3 episodes or more was 75%, not considering a patient without available data. Conclusions: A definite diagnosis of FPIES should be based on OFC, as there are no predictors for OFC positivity other than a history of asymptomatic ingestion. The absence of asymptomatic ingestion history was a negative predictor for the diagnosis of FPIES.