WAILEA, HAWAII – Large numbers of children with atopic dermatitis have been diagnosed with food allergy and placed on strict food-elimination diets on the basis of positive serum immunoglobulin E tests, when in fact oral food challenges conducted in such patients indicate that the vast majority of foods that are being shunned can safely be returned to the diet.
"A shocking number of these kids have false-positive labels of food allergy," Dr. Lawrence F. Eichenfield said at the Hawaii Dermatology Seminar sponsored by Skin Disease Education Foundation (SDEF).
Dr. Lawrence F. Eichenfield
These food-elimination diets can lead to poor weight gain and chronic malnutrition, added Dr. Eichenfield, chief of pediatric and adolescent dermatology at Rady Children's Hospital, San Diego, and professor of pediatrics and medicine (dermatology) at the University of California, San Diego.
"This is an issue that we face in our offices, especially with our moderate to severe atopic dermatitis individuals. We need to have a real sense of the disability that goes on because of empiric food elimination or elimination based on serum IgE tests and nonstandardized tests. Let's consider working with enlightened allergists in the community on giving appropriate challenges or repeating of these foods, because many times they're not a factor at all in the atopic dermatitis," he said.
He cited a recent study by investigators at Denver's renowned National Jewish Health. The study involved 125 children aged 1-19 years (median, 4 years), with atopic dermatitis who were on elimination diets based upon positive serum IgE immunoassay results. The children were hospitalized for medically supervised oral food challenges in which they were given 6-10 doses of a food at intervals of 15-30 minutes.
A negative challenge was defined as no reaction or worsening of atopic dermatitis within a 2-hour observation period, when IgE-mediated symptoms would be expected to become manifest. No challenges were done using foods for which the child had a history of anaphylaxis.
Overall, 93% of the oral food challenges were negative, meaning that those foods could be safely returned to the diet. In all, 100% of challenges to meat, egg, oat, shellfish, and vegetables in the 34 patients on elimination diets involving those foods proved to be negative.
"The results of this retrospective study demonstrate that a primary reliance on serum food-specific IgE testing to determine the need for food elimination diets in children, especially those with atopic dermatitis, is not sufficient," the investigators concluded (J. Pediatr. 2011;158:578-83).
Dr. Eichenfield noted that this conclusion is entirely consistent with the thrust of important new guidelines on the diagnosis and management of food allergy released by a National Institute of Allergy and Infectious Diseases–sponsored expert panel. The guidelines recommend against food avoidance to manage atopic dermatitis, asthma, or eosinophilic esophagitis in the absence of documented or proven food allergy. Furthermore, the guidelines state that serum IgE tests and skin-prick tests are not diagnostic of food allergy, although they can be of assistance in the work-up. Hair analysis, electrodermal tests, kinesiology, and other nonstandardized tests are not recommended.
The new guidelines suggest that only under certain specific conditions should children younger than age 5 years with moderate to severe atopic dermatitis be considered for food allergy evaluation for milk, egg, peanut, wheat, and soy – the handful of foods in which IgE levels and skin-prick testing have the greatest validity in predicting a positive challenge. To be a candidate for this limited food-allergy evaluation, the child needs to have persistent atopic dermatitis despite optimized management and topical therapy, and/or a reliable history of an immediate reaction after consuming a specific food (J. Allergy Clin. Immunol. 2010;126(suppl. 6):S1-58).
"I'd say that this is a new standard for dermatology," Dr. Eichenfield commented. "If a child has a history of a specific food reaction, you want to consider specific food testing because that individual could be at risk for a life-threatening reaction in the future."
"But you don't want to get caught up in a secret allergen search," he added. "Continue to emphasize eczema care as the primary approach to atopic dermatitis."
Dr. Eichenfield serves as a consultant to Coria, Galderma, Promius Pharma, Intendis, and Ortho Dermatologics. He is an uncompensated investigator for numerous pharmaceutical companies. SDEF and this news organization are owned by Elsevier.