Adult OFC for FPIES
The oral food challenge (OFC) is performed to assess resolution of FPIES. It is important to have a shared decision-making process on proceeding with the OFC. It should be discussed with the patient that depending on the severity of the past FPIES reaction, it may be necessary to place a peripheral IV prior to starting the oral food challenge. Additionally, emergency medication will need to be available and placed at the bedside prior to starting the challenge. The medications may include normal saline (IV 20mg/kg), ondansetron (PO, IV, IM 0.15mg/kg/dose; max dose of 16mg/dose) and methylprednisone (IV 1mg/kg). Prior to scheduling the OFC, the patient will be counseled on the duration of the OFC as well as the form and amount of food that will be administered.
Prior to OFC a patient will need to be assessed for the presence of food specific IgE via skin prick testing with commercial extract or fresh food or serum blood ImmunoCAP immunoassay to assess atypical FPIES and the challenge protocol that should be considered based on the presence or absence of IgE
On the day of the challenge, the patient will be required to be in their baseline state of health and with no presenting illness. Current guidelines proposed in the OFC consensus guidelines (Bird et al 2020) have recommended that an FPIES OFC should be measured by 0.06-0.6 grams of protein per kilogram of body weight. The dose is then maxed out at 3 grams of food protein. This of course has been suggested in pediatric patients. For the adult OFC, Gonzalez et al (JACI Pract 2022) recommend calculating the total dose according to the proposal by the Work Group report on OFC testing (ANW et al JACI 2009; Bird et al JACI 2020) and provide the patient with 25% of the total dose and observe for 2 hours and then if no reaction occurred the patient would be given the remainder 75% and observed for 4 hours. They also recommend that the patient have a baseline complete blood count (CBC) would be obtained prior to the challenge and again at 6 hours after the challenge if the patient has reactivity.
Disease resolution would be defined as passing an OFC without any reaction. Patients are then instructed to resume a serving size of food at least 2-3 times per week to maintain their tolerance.