A consensus protocol for the determination of the threshold doses for allergenic foods: how much is too much?

Authors

S. L. Taylor, University of Nebraska-LincolnFollow
S. L. Hefle, University of Nebraska-Lincoln
C. Bindslev-Jensen, Odense University Hospital, Odense, Denmark
F. M. Atkins, National Jewish Medical and Research Center, Denver, CO, USA
C. Andre, Stallergenes, Antony, France
C. Bruijnzeel-Koomen, University Medical Center, Utrecht, the Netherlands
A. W. Burks, Arkansas Children’s Hospital, Little Rock, AR, USA
R. K. Bush, William S. Middleton Veterans Administration Hospital, Madison, WI, USA
M. Ebisawa, National Sagamihara Hospital, Kanagawa, Japan
P. A. Eigenmann, University of Turku
A. Host, Odense University Hospital, Odense, Denmark
Jonathan O. B. Hourihane, University of Southampton, Southampton, UK
E. Isolauri, University of Turku, Turku, Finland
D. J. Hill, Royal Children’s Hospital, Parkville, Australia
A. Knulst, University Medical Center, Utrecht, the Netherlands
G. Lack, St. Mary’s Hospital, London, UK
H. A. Sampson, Mt Sinai School of Medicine, New York, NY
D. A. Moneret-Vautrin, Department of Internal Medicine, Clinical Immunology and Allergology, University Hospital, Nancy, France
F. Rance, Hopital des Enfants, Toulouse, France
P. A. Vadas, Wellesley Central Hospital, Toronto, Ont., Canada
J. W. Yunginger, Mayo Clinic, Rochester, MN, USA
R. S. Zeiger, Kaiser Permanente Medical Center, San Diego, CA, USA
J. W. Salminen, Health Products and Foods Branch, Chemical Health Hazard Assessment Division, Ottawa, Canada
C. Madsen, Danish Veterinary & Food Administration
P. Abbott, Food Standards Australia New Zealand, Canberra, Australia

Document Type

Article

Date of this Version

January 2004

Comments

Published in Clin Exp Allergy 2004; 34:689–695.

Abstract

Background:While the ingestion of small amounts of an offending food can elicit adverse reactions in individuals with IgE-mediated food allergies, little information is known regarding these threshold doses for specific allergenic foods. While low-dose challenge trials have been conducted on an appreciable number of allergic individuals, a variety of different clinical protocols were used making the estimation of the threshold dose very difficult.

Objective: A roundtable conference was convened to develop a consensus clinical protocol for low-dose challenge trials for the estimation of threshold doses for specific allergenic foods.

Methods: In May 2002, 20 clinical allergists and other interested parties were invited to participate in a roundtable conference to develop consensus of the key elements of a clinical protocol for low-dose challenge trials.

Results: A consensus protocol was developed. Patients with convincing histories of food allergies and supporting diagnostic evidence including past challenge trials or high CAP–RAST scores can be enrolled in low-dose challenge trials. Care must be taken with younger patients to assure that they have not outgrown their food allergy. An approach was developed for the medication status of patients entering such trials. Challenge materials must be standardized, for example, partially defatted peanut flour composed of equal amounts of the three major varieties of peanuts (Florunner, Virginia, Spanish). Challenge materials must be appropriately blinded with sensory evaluation used to confirm the adequacy of blinding. A double-blind, placebo-controlled design should be used for low-dose challenge trials. Low-dose challenge trials would begin at doses of 10 mg of the allergenic food and would continue with doses of 100 mg and 1 mg followed by specific higher doses up to 100 mg depending upon the expert judgment of the physician; even higher doses might be applied to assure that the patient is indeed reactive to the particular food. A 30-min time interval would be used between doses, and reactive doses would be expressed as both discrete and cumulative doses. The goal of each challenge would be to develop objective symptoms; trials should not be discontinued on the basis of subjective symptoms only. Statistically, a minimum of 29 patients would be enrolled in low-dose challenge trials for each allergenic food because 0 reactors out of 29 patients at a particular dose allow the conclusion that there is 95% certainty that 90% of allergic individuals will not react to that dose.

Conclusion: A consensus protocol was developed. Using this protocol, it will be possible to estimate threshold doses for allergenic foods, the lowest amount that elicits mild, objective symptoms in highly sensitive individuals.