Peanut Allergen Threshold Study (PATS): Novel single-dose oral food challenge study to validate eliciting doses in peanut allergic children

Publication date: Available online 24 February 2017
Source:Journal of Allergy and Clinical Immunology
Author(s): Jonathan O'B. Hourihane, Katrina J. Allen, Wayne G. Shreffler, Gillian Dunngalvin, Julie A. Nordlee, Giovanni A. Zurzolo, Audrey DunnGalvin, Lyle C. Gurrin, Joseph L. Baumert, Steve L. Taylor
BackgroundEliciting doses (ED) of allergenic foods can be defined by the distribution of threshold doses for individuals within a specific population. ED05 is the dose that elicits a reaction in 5% of allergic subjects. The predicted ED05 for peanut (PN) is 1.5 mg of peanut protein (6 mg whole peanut).ObjectiveWe sought to validate the predicted peanut ED05 (1.5 mg) with a novel single dose challenge.MethodsConsecutive eligible peanut allergic children in 3 centres were prospectively invited to participate, irrespective of previous reaction severity. Predetermined criteria for objective reactions were used to identify ED05 single dose reactors.Results518 children (mean age 6.8 years) were eligible. No significant demographic or clinical differences were identified between 381(74%) participants and 137 (26%) non-participants or between subjects recruited at each centre. 378 children (206 male) completed the study. Almost half the group reported ignoring precautionary allergen labelling. 245 (65%) experienced no reaction to the single dose of peanut. 67 (18%) reported a subjective reaction without objective findings. 58 (15%) experienced signs of a mild and transient nature that did not meet the pre-determined criteria. Only 8 subjects (2.1%, 95% CI 0.6%-3.4%) met the pre-determined criteria for an objective and likely related event. No child experienced more than a mild reaction, 4 of the 8 received oral antihistamines only and none received epinephrine. Food allergy related quality of life improved from baseline to 1 month post challenge regardless of outcome (eta squared = 0.2, p <0.0001). Peanut SPT, peanut and Ara h 2 spIgE levels were not associated with objective reactivity to PN ED05.ConclusionA single administration of 1.5 mg PN protein elicited objective reactions in fewer than the predicted 5% of peanut-allergic subjects. The novel single dose OFC appears clinically safe and patient-acceptable, regardless of the outcome. It identifies the most highly dose-sensitive food allergic population, not otherwise identifiable using routinely available peanut SPT or spIgE levels but this single-dose approach has not yet been validated for risk assessment of individual patients.

Teaser

The derived ED05 for peanut (1.5mg peanut protein) was given in a single dose to 378 peanut allergic subjects. Only 8 subjects (2.1%) met predetermined criteria for an objective reaction, suggesting the derived ED05 could be used as a safe reference dose.


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