Impact of Allergic Reactions on Food-Specific IgE Concentrations and Skin Test Results

Abstract

Background: Although there is concern that food allergy reactions may negatively affect the natural history of food allergy, the impact of reactions on food-specific IgE (sIgE) levels or skin prick test (SPT) wheal size is unknown.

Objective: To measure the effects of allergic reactions on SPT wheal size and sIgE concentrations to milk, egg, and peanut.

Methods: Participants included 512 infants with likely milk or egg allergy enrolled in a multicenter observational study. Changes in sIgE level and SPT wheal size to milk, egg, and peanut were measured before and after oral food challenge (OFC) or accidental exposure for 377 participants.

Results: The median age of the cohort at the time of analysis was 8.5 years (67% males). There were no statistically significant changes in sIgE level or SPT wheal size after positive OFC to milk, egg, or peanut (n = 20-27 for each food). Change in sIgE level and SPT wheal size was measured after 446 and 453 accidental exposure reactions, respectively. The median change in sIgE level was a decrease of 0.33 kU(A)/L (P < .01) after milk and 0.34 kU(A)/L (P < .01) after egg reactions, but no other statistically significant changes in sIgE level or SPT wheal size were observed for milk, egg, or peanut. When we limited the analysis to only those participants who had diagnostic testing done within 6 months of an accidental exposure reaction, we found that peanut SPT wheal size increased by 1.75 mm (P < .01), but a significant increase was not noted when all participants with testing done within 12 months were considered.

Conclusions: The results suggest that reactions from OFCs and accidental exposure are not associated with increases in sensitization among children allergic to milk, egg, or peanut.

Keywords: Food allergy; IgE; Natural history; Skin prick test.