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

Abstract

Background: Although 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 are not well known.

Objective: To describe almond oral challenge outcomes and assess the predictive value of clinical testing.

Methods: A total of 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 National Institute of Allergy and Infectious Diseases 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 level was 0.89 kU/L (range, <0.35 to >100 kU/L), median skin prick test wheal diameter was 4.0 mm (range, 0-28 mm), and 475 subjects (81%) were sensitized to almond. Failure was associated with higher almond specific IgE level (P < .001), larger almond skin prick test wheal diameter (P = .001), higher peanut IgE level (P = .003), and a history of almond reaction (P < .029). Almond specific IgE level, almond skin prick test wheal diameter, and age at challenge combined demonstrated good predictive value for grade 2/3 allergic reactions by receiver-operating characteristic analysis (area under the curve, 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. Although reactions are usually uncommon and mild, anaphylaxis is possible with high almond sensitization.

Keywords: Almond allergy; Almond hypersensitivity; Food allergy; Oral food challenge; Safety.