Background: Hazelnut allergy in adults is often birch pollen related, whereas in children, non-pollen-related hazelnut allergy is more frequent. Objective: To compare the differences in hazelnut allergy between children and adults with regard to severity, aetiology and diagnostic value of routinely available data. Methods: Adults (n = 120) who underwent a double-blind placebo-controlled food challenge (DBPCFC) for hazelnut were selected and compared to 151 hazelnut-challenged children from a previous study. Univariate and multivariate logistic regression analyses were performed to build a prediction model. The area under the curve (AUC) of the ROC curve was determined for level of hazelnut-specific IgE, skin prick test (SPT) and the prediction model. Results: Hazelnut allergy was confirmed by DBPCFC in 95/120 (79%) adults, 77% had only subjective and 23% objective symptoms, whereas in children, 63% had objective symptoms to hazelnut. Within the group of children, the frequency of severe hazelnut allergy was higher in younger than in older children. A concomitant birch pollen allergy was more common in adults (82%) than in children (39%) with a hazelnut allergy. A detailed history with allergic symptoms to previous ingestion of hazelnut had the highest diagnostic value in adults, while in children, SPT to hazelnut extract showed the highest level of discrimination between clinical reactivity and tolerance to hazelnut. Conclusions and Clinical Relevance: Hazelnut allergy differs between children and adults with respect to frequency of severity, aetiology and relevance of diagnostic parameters. Therefore, age has to be taken into account in the diagnostic work-up of a hazelnut allergy.

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Clinical and Experimental Allergy
Erasmus MC: University Medical Center Rotterdam

Masthoff, L. J. N., van Hoffen, E., de Reus, A., Boonacker, C. W., Bruijnzeel-Koomen, C. A., Pasmans, S., & Knulst, A. (2014). Hazelnut allergy differs between children and adults in frequency of severity, aetiology and relevance of diagnostic parameters. Clinical and Experimental Allergy, 44(12), 1539–1545. doi:10.1111/cea.12440