Outcome of oral food challenges in children in relation to symptom-eliciting allergen dose and allergen-specific IgE

Background Oral food challenge (FC) protocols are discussed with reference to starting doses, dose increments, safety, and predictability of results. The aim of this study was to evaluate the relation of eliciting allergen doses, specific IgE levels and predictive factors to the outcome of FCs in children. Methods In 869 children (median age 1.2 years), FCs were performed with cow's milk (n = 633), hen's egg (n = 456), wheat (n = 265) and/or soy (n = 317) starting at 35 mg of protein. Each of the seven doses was administered every 30 min using semi-log increases. Severity of symptoms was graded from I to V. IgE was determined prior to challenges. Results Of the children allergic to egg or milk, 9% and 10%, respectively, experienced reactions already at the first dose. Of these, 14% (egg) and 4% (milk) experienced grade IV reactions. In contrast, few children reacted to the first doses of wheat or soy, and most reactions occurred after the maximum dose. For all allergens, grade V reactions did not occur. However, grade IV reactions were seen at all eliciting doses. Elevated specific IgE level, young age and a history of atopic dermatitis were associated with a positive challenge outcome for milk or egg, and also IgE levels were associated with lower eliciting allergen doses and more severe symptoms. Conclusion Oral FCs bear a risk of severe reactions at all dose levels. Doses of 35 mg protein induced symptoms in up to 10% of children allergic to milk or egg. However, food-specific IgE levels are of limited clinical value for the estimation of FC reactions.