P8: THE EFFICACY OF SKIN TESTING, SPECIFIC IgE AND BASAL ACTIVATION TESTING IN PREDICTING THE OUTCOME OF ORAL PROVOCATION CHALLENGES IN CHILDREN WITH SUSPECTED BETA‐LACTAM ALLERGY

Abstract

Beta-lactam allergy can be currently diagnosed based on positive skin testing, serum-specific IgE, or provocation challenge. In adults, sensitivity and specificity of skin testing and serum-specific IgE in the context of assessing distant reactions are poor. Paediatric data in this regard are missing. 135 children with a distant (over 6 months) reported beta-lactam allergy were assessed. Data collection included results of skin-prick testing, intradermal testing, oral provocation-challenge (1/10th and full dose), 5-day prolonged course (EC), serum specific IgE and Basophil Activation Testing (BAT). 135 children underwent oral provocation-challenges. Two (1.4 %) reacted immediately to 1/10th dose and 1 to the full dose. All children had skin testing. One had positive skin-prick testing and passed oral provocation-challenge. 3 had positive intradermal testing, 1 reacted immediately to a tenth dose, 2 passed oral provocation-challenge. 132 children went home on a 5-day EC with the challenge antibiotic, 10 (7.5%) reacting. All other children had negative testing. Ten children out of 135 had a positive serum-specific IgE for at least one beta-lactam, all of these children passed the oral provocation and EC challenge. Eighty children were tested by BAT, all were negative, including the 13 children with reactions to the oral provocation-testing. In our preliminary data set of children with distant antibiotic reactions, serum beta-lactam specific IgE, BAT testing and skin testing were poor predictors of positive reactions to provocation testing, mimicking recent observations in adults. For the 135 children challenged, the immediate reactions were urticarial rashes and no anaphylaxis; the non-immediate reactions during the prolonged course were rashes only. This further strengthens the data that oral provocation testing in children with distant reactions is safe and that skin testing, BAT and testing for specific IgE add very little to identify those with a true allergy.