Analysis of Oral Food Challenge Outcomes in IgE-mediated Food Allergies to Almond in a Large Cohort

Abstract

While almond-specific IgE-mediated food allergies have traditionally been equated with other tree nut allergies, outcomes of oral food challenges to almond and the utility of clinical testing to predict IgE-mediated almond hypersensitivity is not well known. To describe almond oral challenge outcomes and assess the predictive value of clinical testing. 603 almond challenges performed for 590 patients, aged 1 to 66 years, were analyzed from Massachusetts General Hospital allergy practices. Reactions were graded using the Niggemann and Beyer allergic reaction grading system and the Sampson 2006 NIAID anaphylaxis definition. Almond challenges included 545 passes (92%), 15 (3%) indeterminates, and 30 (5%) failures, in contrast with 31% challenge failures for other foods. Most reactions were mild; 21 (4%) had Grade 2/3 allergic symptoms, and 3 (0.5%) had anaphylaxis. Median almond-specific IgE was 0.89 kU/L (range: <0.35, >100), median skin prick test (SPT) was 4.0 mm (0, 28), and 475 subjects (81%) were sensitized to almond. Failure was associated with higher almond-specific IgE (p<0.001), larger almond SPT (p=0.001), higher peanut IgE (p=0.003), and a history of almond reaction (p<0.029). Almond-specific IgE, almond SPT, and age at challenge combined demonstrated good predictive value for Grade 2/3 allergic reactions by ROC analysis (AUC 0.83). The proportion of failed almond challenges (5%) was low in contrast with other allergens, suggesting that some almond challenges may be safely conducted with higher patient-to-staff ratios or potentially introduced at home. Though reactions are usually uncommon and mild, anaphylaxis is possible with high almond sensitization.