New Guidelines Help Doctors Diagnose Food Allergy

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According to the most recent surveys, the incidence of food allergies continues to climb, with anywhere from 1% to 10% of Americans unable to safely consume common foods such as milk, eggs or nuts. But how reliable are these figures?

Health experts acknowledge that while the rise in food allergies is real, particularly among young children, the extent of the boost is trickier to nail down. There is no standard for diagnosing them, which means that doctors use varying criteria to define an allergy. An estimated 50% to 90% of currently diagnosed food allergies, according to the latest report, are not true allergic reactions, but sensitivity to foods. (More on Can Overuse of Antibacterial Soap Promote Allergies in Kids?)

That’s why in 2008, the National Institute on Allergy and Infectious Diseases (NIAID) of the National Institutes of Health embarked on a project to create guidelines for diagnosing and managing food allergies. Working with more than 30 other professional, government and advocacy organizations, including the American Academy of Allergy, Asthma and Immunology and the Food Allergy and Anaphylaxis Network, the group issued its final recommendations on Monday.

The guidelines are not binding for practicing physicians, but NIAID officials hope they will help streamline diagnoses for doctors in all specialties, including pediatricians and family practitioners, as well as allergists.

In analyzing more than 10,000 studies on food allergies for the report, “We found so many different definitions of food allergy,” says Dr. Matthew Fenton, chief of the asthma, allergy and inflammation branch of NIAID and a primary co-author of the report. “We are trying to get everybody to use a common set of tools to diagnose food allergy and best practices for managing them.” (More on Cheers! Could Hypoallergenic Wine Be on the Horizon?)

The new guidelines clarify which tests are considered scientifically validated for detecting true food allergies, and outlines a strategy for helping doctors distinguish patients who have sensitivities to food — those who are not able to tolerate a food — and those who have true allergic reactions, which can include anaphylactic shock and even death.

In order to diagnose a food allergy, the guidelines advise, ideally, confirming the presence of four factors: a report from the patient (or from the parent, in the case of children) of an adverse reaction such as a rash, intestinal difficulties, difficulty breathing or other reactions after consuming a particular food; a blood test that measures antibodies indicating an allergic immune reaction, a skin prick test with the allergen that shows an adverse reaction; and finally, the gold standard, a positive oral challenge test, in which the patient ingests a small amount of the food allergen.

Realistically, the panel members acknowledge that not all four tests are always possible. At routine checkups, particularly when parents are concerned that their children may have food allergies, many physicians currently test youngsters for antibodies or with the skin prick test; if the results are positive, they diagnose the child with a food allergy and advise parents to restrict their children’s diet. (More on Got Allergies? Be Careful How You Hook Up)

But restricting the diet should not be the end goal, says Dr. Hugh Sampson, a pediatrician at Mount Sinai School of Medicine’s Jaffe Food Allergy Institute and another primary co-author of the report. Instead, the guidelines should help doctors realize that eliminating the potential allergen should just be one step in the process of diagnosing a food allergy.

“Blood tests and skin prick tests simply tell us that an individual is sensitized or has made antibodies in response to a particular food, but they don’t tell us whether or not they will actually have allergic symptoms if they were to eat the food,” he says.

Physicians should monitor what happens when a child with a suspected food allergy stops eating the offending food, and if the symptoms stop, then consider an oral challenge test to confirm the allergy.

The guidelines also urge doctors to follow up with any diagnoses of food allergies with additional tests at least once a year, particularly for children who are allergic to milk and eggs, since these reactions tend to disappear with age. (More on Can Peanut Allergies Develop in the Womb?)

The guidelines also reinforce advice from the American Academy of Pediatrics, which recently revised its recommendations for pregnant women, assuring them that there is no scientific evidence to support avoiding potential allergy-causing foods such as nuts or eggs during pregnancy or breast-feeding. The report also supports current recommendations that children with known egg allergies should avoid influenza vaccinations since these shots are still made using egg-based methods for growing the flu virus.

In addition to clarifying diagnoses, the report also provides advice about managing allergic reactions, including anaphylactic shock. The panel members stressed that shock can occur in various stages, from mild to severe, and while there is no treatment for a food allergy reaction, use of epinephrine to ease immediate shock symptoms is critical. The report urges allergy patients to always be prepared with an epinephrine dose in case of accidental ingestion of a food allergen.

The panel’s goal, says Fenton, was to provide physicians with an accessible and standardized way to handle patients with food allergies, and to ultimately provide better care as well as to clarify the prevalence of true food allergies. “As new data comes out, we will certainly update the guidelines,” he says, “but we hope these guidelines will be used broadly throughout the clinical community to improve diagnosis and management of food allergies.”

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