Study population
Participants were selected from the EAT and EAT-On studies and informed consent was obtained. (11) The EAT study reviewed the children at 3 months (3m), 12 months (12m), and 36 months (36m) of age with the primary outcome being the diagnosis of IgE mediated allergy between 1 and 3 years of age. The EAT-On study was the follow-on study conducted to establish whether the effects seen at the end of the EAT study represented a delay in food allergy onset or sustained tolerance. The EAT-On cohort was seen between ages 7-11 years old.
Allergic status was confirmed by either a positive OFC or based on clinician-taken history of reaction and SPT>5mm if an OFC was not conducted. Tolerance was determined by a negative OFC and/or consumption of peanut regularly in the child’s diet as defined by the EAT-On study protocol (i.e. at least 3g of peanut protein 3 times in the last 6 months). If the child was not consuming peanut and OFC was indeterminate or not available, in the presence of SPT=0 mm they were also considered not allergic.
Skin prick tests (SPT)
SPT were performed to peanut and aeroallergens on the forearm or back, using a standardized lancet (ALK-Abello), peanut extract (ALK-Abello), histamine 10 mg/mL or 50% glycerol, 50% buffered saline. Skin test sites were measured after 15 minutes as the average of the widest diameter and perpendicular of the wheal.