Atopic dermatitis increases food allergy risk
MedWire News: Atopic dermatitis could be a precursor to allergic diseases rather than a consequence, dermatologists warn.
Jon Hanifin, from Oregon Health and Science University in Portland, USA, told delegates at the annual Meeting of the American Academy of Dermatology in New Orleans, Louisiana, USA, that, given 6 to 10% of children have atopic dermatitis and up to one-third of these individuals may have documented food allergy, the number of affected children is significant.
"In most cases, patients experience atopic dermatitis before food allergies, so it is important for parents of infants and small children affected by this skin condition to be aware of the risk of food allergies," he said.
Hanifin and colleagues conducted a 5-year study in babies aged 3 to 18 months and found that in those with atopic dermatitis, even those with mild symptoms, around 15% had definite food allergies, with the incidence higher in those with severe symptoms.
However, he commented on the challenges surrounding the diagnosis of food allergies in patients with atopic dermatitis because they have increased levels of immunoglobulin E antibodies, which is sometimes used as an indication of food allergies. This, therefore, could mean some patients with atopic dermatitis being wrongly diagnosed and treated for food allergies.
Hanifin said that a positive skin or blood test for food allergy should only be considered positive if it is confirmed by an actual food challenge - "where you feed patients the food indicated by tests and see if they have an immediate reaction to it," he explained.
He believes that new guidelines issued by the National Institute of Allergy and Infectious Diseases in December will help dermatologists to diagnose food allergies in atopic dermatitis patients.
According to these guidelines, it is recommended that children younger than 5 years old with moderate to severe atopic dermatitis should be considered for food allergy evaluation for milk, egg, peanut, wheat, and soy, if the child has at least one of the following criteria: persistent atopic dermatitis in spite of optimized management and topical therapy or a reliable history of an immediate reaction after ingestion of a specific food.
Hanifin suggested that atopic dermatitis makes people susceptible to food allergies because it compromises the skin barrier allowing it to be penetrated by allergens such as food, which then cause adverse reactions.
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By Lucy Piper