Scientific Study

BACKGROUND: 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. OBJECTIVE: To describe almond oral challenge outcomes and assess the predictive value of clinical testing. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.