Food Allergy Guidelines Aim to Reduce Misdiagnosis

Probably every family physician in clinical practice has been confronted by patients who insist that they (or their children) are allergic to one food or another based on nonspecific gastrointestinal or other complaints. However, multiple studies have demonstrated that at least 50 percent -- and possibly as much as 90 percent -- of self-reported food allergies are not allergies at all.

With that in mind, the National Institute of Allergies and Infectious Diseases, or NIAID, has released food allergy guidelines designed to help physicians -- including family doctors -- diagnose true food allergies and manage the care of patients with these conditions.

"Many people say they have food allergies, but not all of them are really allergies," said Barbara Yawn, M.D., MSc., director of research at the Olmsted Medical Center and adjunct professor of family and community health at the University of Minnesota. A member of the guideline panel, Yawn told AAFP News Now that the oral food challenge is the preferred test for diagnosing such allergies.

"Food allergies, other than those causing anaphylaxis, should be tested, and the best way to test is by removing the food from the diet for several days and then reintroducing it," she said.

The guidelines -- which were published as a supplement to The Journal of Allergy and Clinical Immunology -- contain more than 40 clinical recommendations, including tests that should and should not be used to diagnose food allergy.

Matthew Fenton, Ph.D., chief of the Asthma, Allergy and Inflammation Branch of the Division of Allergy, Immunology and Transplantation at NIAID, emphasized during a news conference held to announce the release of the guidelines that they were not written "by allergists for allergists" but, rather, are intended to be used across medical specialties, including family medicine.

Hugh Sampson, M.D., professor of pediatrics and dean for translational biomedical sciences at the Mount Sinai School of Medicine in New York and director of the Jaffe Food Allergy Institute, said during the news conference that skin and blood tests may indicate sensitivity but do not indicate whether clinical symptoms will develop.

"One of the most concerning issues we see is confusion between the concept of sensitivity and clinical reactivity," said Sampson, who is a past president of the American Academy of Allergy, Asthma and Immunology. "We see a lot of physicians order a large number of blood tests for various foods, and when they find a small amount of antibodies present, they indicate to the individual that they're allergic to foods and shouldn't ingest them."

According to Sampson, this practice leads to many children unnecessarily being put on highly restrictive diets. "When we see them and go through the food challenge process, they don't react to most foods," he said.

"One of the biggest things we'd like to see based on guidelines is that the diagnosis of food allergy isn't just doing a skin test or just doing a blood test or (accepting a patient's or parent's) report of a food allergy."

Instead, Sampson said appropriate diagnosis requires taking a thorough medical history, ordering appropriate lab tests, and, in some cases, conducting an oral food challenge. However, many physicians are reluctant to perform oral food challenges because the process is time-consuming, carries some risk and is not well compensated, he said. Still, the results of such challenges can be illuminating.

"We have plenty of good evidence that self-reporting wildly overestimates the incidence of food allergy," Fenton said. "It's important that patients and their families know that symptoms of food allergies can mimic several other very legitimate diseases, such as food intolerance or various gastrointestinal diseases."

The guidelines also identify a dozen "nonstandardized and unproven" diagnostic procedures to avoid.

In addition to diagnosis, the guidelines cover several other topics:

The NIAID -- which is part of the NIH -- estimates that food allergies affect 5 percent of children ages 5 years and younger and 4 percent of teens and adults.

"It's going to be very important for patients to work with their physicians to develop the correct diagnosis so the correct management strategy can be put in place," Fenton said.