Predictive values of component-specific IgE for the outcome of peanut and hazelnut food challenges in children

Background: Oral challenges are the gold standard in food allergy diagnostic, but time-consuming. Aim of the study was to investigate the role of peanut-and hazelnut-component-specific IgE in the diagnostics of peanut and hazelnut allergy and to identify cutoff levels to make some challenges superfluous. Methods: In a prospective and multicenter study, children with suspected peanut or hazelnut allergy underwent oral challenges. Specific IgE to peanut, hazelnut, and their components (Ara h 1, Ara h 2, Ara h 3, and Ara h 8, Cor a 1, Cor a 8, Cor a 9, and Cor a 14) were determined by ImmunoCAP-FEIA. Results: A total of 210 children were challenged orally with peanut and 143 with hazelnut. 43% of the patients had a positive peanut and 31% a positive hazelnut challenge. With an area under the curve of 0.92 and 0.89, respectively, Ara h 2 and Cor a 14-specific IgE discriminated between allergic and tolerant children better than peanut-or hazelnut-specific IgE. For the first time, probability curves for peanut and hazelnut components have been calculated. A 90% probability for a positive peanut or hazelnut challenge was estimated for Ara h 2-specific IgE at 14.4 kU/l and for Cor a 14-specific IgE at 47.8 kU/l. A 95% probability could only be estimated for Ara h 2 at 42.2 kU/l. Conclusions: Ara h 2-and Cor a 14-specific IgE are useful to estimate the probability for a positive challenge outcome in the diagnostic work-up of peanut or hazelnut allergy making some food challenges superfluous.