Oral Food Challenge Aids Tree Nut Allergy Diagnosis
It may be unnecessary for individuals with a single tree nut allergy to avoid all tree nuts, according to the results of a recent study.
In order to better understand the characteristics and outcomes of tree nut oral food challenges in patients with tree nut allergy or sensitization, researchers conducted an analysis of 156 tree nut oral food challenges conducted at a single medical center from 2007 to 2015. The researchers categorized the participants as allergic (symptomatic after tree nut ingestion), sensitized (having positive results on a skin prick or serum-specific immunoglobulin E test [slgE]), or avoiding nuts despite lack of clinical history. Participants were not given oral challenges to nuts from which they had had an allergic reaction.
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Overall, passage rate was 86% for 156 tree nut allergy tests conducted among 109 patients. Further, rates were 76% among patients with a history of tree nut allergy who were challenged to another tree nut to which they were sensitized, 91% among participants with sensitization only, 89% in those with a tree nut slgE level lower than 2 kUA/L and 69% for those with a tree nut slgE level of 2 kUA/L or more, 96% among participants with peanut allergy and tree nut co-sensitization, and 61% among those with a tree nut skin prick test mean wheal size of 4.8 mm in those passing vs 9 mm in those failing.
“[Tree nut] challenges are frequently passed in patients with [tree nut] sensitization with or without a history of [tree nut] reactivity despite a [tree nut skin prick test] wheal of at least 3 mm or a [tree nut] sIgE level of at least 2 kUA/L,” the researchers concluded.
“Nearly all patients with peanut allergy and [tree nut] co-sensitization passed the [tree nut] challenge, questioning the clinical relevance of ‘co-allergy.’”
Couch C, Franxman T, Greenhawt M. Characteristics of tree nut challenges in tree nut allergic and tree nut sensitized individuals [published online March 27, 2017]. Ann Allergy Asthma Immunol. doi: dx.doi.org/10.1016/j.anai.2017.02.010