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Avoiding Harm in the Diagnosis and Treatment of Food Allergies

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INDIANAPOLIS, Indiana. If there’s one truth that David R. Stukus, MD, has come to realize in his two years as director of a food allergy treatment center, it’s that food allergies in children and adolescents are overdiagnosed and misdiagnosed.

“When they are diagnosed with a food allergy, many families do not receive the proper education to help them understand the risk as well as self-management and prognosis,” he said at the annual meeting of the Society for Pediatric Dermatology. “They are left to fend for themselves, which leads to increased anxiety. If they don’t understand what it means to deal with their child’s food allergy, they will think they are a ticking time bomb,” Stukus said. Director of the Food Allergy Treatment Center and Professor of Pediatrics in the Department of Allergy and Immunology at the National Children’s Hospital in Columbus, Ohio.

During his presentation, he spoke to clinicians about best practices for diagnosing and treating food allergies and shared cautionary tales of unverified claims, unnecessary tests, and potential harm to misdiagnosed patients.

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While food allergies can be serious and life-threatening, they can also be managed, he continued. This does not mean that children with food allergies cannot go to school, attend baseball games, or participate in activities that any other child would do. “Telling someone about following a restricted diet is bad advice,” he said. “It can cause real harm.”

Stukus defined food allergy as an immunological reaction to an allergen that results in reproducible symptoms with every exposure. “The most common thing we see is IgE-mediated food allergy, which often occurs within minutes of eating certain foods,” he said.

Food intolerance, on the other hand, is a non-immunological reaction to a food that causes gastrointestinal symptoms when exposed. “It can come and go with time,” he said. “The most common example is lactose intolerance.”

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Then there’s food sensitivity, which Stukus says is not a medical term but a marketing term that is often applied to various symptoms without evidence to support its use.

“On the Internet, you will find many companies selling food sensitivity tests,” he said. “Gluten-free products are currently a billion dollar industry. There are no validated tests to diagnose food sensitivities. All blood tests measure IgG, memory antibodies. it, but these companies will check all these things, and when they get back to the advanced level, they will say, “Aha! It’s your food sensitivity and that’s why you don’t sleep well at night.” To illustrate the harm that food allergy testing can do, he spoke of a 6-year-old girl who presented to his clinic a few years ago with typical symptoms of allergic rhinitis. The parent reported sneezing in the presence of dogs; itchy, watery eyes in spring; recurrent cough; and frequent upper respiratory tract infections.

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The referring doctor ordered an allergy panel that noted a long list of foods the girl was allegedly allergic to, including bananas, egg white, cod and peanuts. “This family was told to remove all these foods from their diet,” Stukus said. “Interestingly, she was seen by this doctor for an environmental allergy assessment, but only cats, cockroaches, dogs, and dust mites were included in the test. They didn’t even include spring pollen allergy. such tests.

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Food sensitization is not the same as a food allergy, he continued, noting that about 30% of all children will have IgE to peanuts, milk, eggs and shrimp, but only about 5% have a true allergy to these foods.

“If we only do IgE testing, we will be diagnosing the vast majority of people with food allergies that they don’t actually have,” he said. “Food allergies are diagnosed by history and then confirmed by testing. With regard to IgE-mediated food allergies, we know that milk, eggs, wheat, soy, fish fins, shellfish and peanuts account for over 90% of all food allergies. Can any food potentially cause a food allergy? Yes, potentially, but we know that most fruits, vegetables and grains are unlikely to cause allergies.”

IgE-mediated food allergy is objective, begins immediately, and is reproducible with every contact with an allergen, regardless of its form. Typical symptoms include hives, swelling, vomiting, runny or stuffy nose, wheezing, hypotension, and anaphylaxis.

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“We can also pinpoint infants who are more at risk of developing food allergies,” Stukus said. Infants with refractory atopic dermatitis often progress to eczema, food allergies, allergic rhinitis, and asthma, the so-called “allergic march.”

“Family history also plays a role, but not as important,” he said. In terms of diagnostic tools, skin prick tests detect the presence of specific IgE associated with skin mast cells and have a high negative predictive value and a low positive predictive value (about 50%).

With a serum-specific IgE test, IgE levels for food and/or inhalant allergens can easily be obtained using routine venipuncture. The results are presented in the range from 0.1 kU/L to 100 kU/L, and some are presented as arbitrary classes with severity levels from 1 to 5.

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“I strongly discourage anyone from paying attention to arbitrary classes [on these reports]Stukus said. – It’s pointless. Absolute value is all that matters.”

He added that both the skin test and the blood test have a high rate of false positives. “We really need to use history to determine what tests we do; they were never intended to be used as screening tests, but they are used as screening tests on a regular basis,” he said. “There are also no indications for rapid testing. The reason is that we see a lot of cross-reactivity in testing. detectable IgE will show up, but they are much less likely to actually have a clinical reaction to foods like soy and beans.”

Stukus advises clinicians to consider certain questions before ordering an allergen panel, the first being: Do I have the knowledge and experience to correctly interpret the results?

“If you don’t know how to interpret the test, you probably shouldn’t order it at all,” he said. “If you have the knowledge to interpret the results, will they help in making a diagnosis or managing change? If not, why are you testing just for testing purposes? There is no clinical indication for ordering a food allergy panel.” Stukus recommended a review of unproven food adverse reaction tests published in 2018 in the Journal of Allergy and Clinical Immunology. Potential harms from unproven food allergy tests include cost, unnecessary diet avoidance, and a delay in diagnosing the underlying disease, Stukus said. During the COVID-19 pandemic, he observed an increase in patients with orthorexia, which he described as an eating disorder characterized by an unsafe obsession with healthy food that is deeply ingrained in a person’s way of thinking to the point of interfering with daily life.

“If you take someone who initially had anxiety and then give them a list of foods that they supposedly can’t eat, it will create even more anxiety,” he added. “We see it in the results of these tests.”

Stukus said he is a consultant for Before Brands, Kaleo and Novartis. He is also Associate Editor of Annals of Allergy, Asthma and Immunology.

This article originally appeared on MDedge.com, part of the Medscape professional network.

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