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New guidelines established for diagnosis, management of food allergy
Guideline creators seek to standardize physicians’ approaches.
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Recent increases in reports of food allergy seem to mirror reports of increases in other allergic diseases like asthma, hay fever, atopic dermatitis or eczema, but the reasons why pediatricians are seeing those increases are unclear. A new set of guidelines — “Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-sponsored Expert Panel” — attempts to clarify what is leading to the increases by standardizing diagnostic criteria for food allergy.
Recent data — commissioned by the National Institute of Allergy and Infectious Diseases (NIAID) and conducted by the RAND Corporation — support the idea that food allergy prevalence may be increasing. Their data revealed that food allergy affects about 5% of children and 4% of adults in the United States, and this number is increasing. But it was unclear whether these rates were due to actual increases, inconsistent diagnostic methods or rather just an increased awareness of the condition
“There is awareness on both sides,” Matthew J. Fenton, PhD, member of the coordinating committee overseeing the guidelines and chief of the asthma, allergy and inflammation branch at NIAID, told Infectious Diseases in Children. “The physicians are aware that food allergies and food intolerances are real diseases and are difficult to distinguish from each other. But certainly, parents of young children are extremely aware of food allergies and much more so now than they were 10 years ago or longer.”
“Part of the increase is real, but the other part is that, as a result of the perception that there is more food allergy, more diagnostic tests are being run,” said Joshua A. Boyce, MD, chair of the expert panel and associate professor of medicine at Harvard Medical School in Boston. “But simply having a positive test does not necessarily mean you are allergic.”
Importance of diagnostics
The gold standard of food allergy diagnosis remains the oral food challenge, said A. Wesley Burks, MD, member of the expert panel and professor and chief of pediatric immunology at Duke University in Durham, N.C.
Because of a food challenge’s benefits, the guidelines recommend use but also recognize that certain features of the test preclude widespread implementation.
“It can take up to a day to do a single food test, which means you have to have a nurse and a physician there for that period of time, so it is obviously very expensive, but it also puts the patient at risk for having an anaphylactic reaction,” said expert panel member Hugh A. Sampson, MD, professor of pediatrics at Mt. Sinai School of Medicine.
Another aspect of diagnosing food allergy is patient identification, but the guidelines stress verification of patient and family history reports.
Fifty percent to 90% of presumed food allergies are not actual “allergies,” according to Lawrence F. Eichenfield, MD, expert panel member, professor of pediatrics and medicine and chief of pediatric and adolescent dermatology at Rady Children’s Hospital, San Diego and University of California, San Diego. Rather he said, what many patients and families identify as “allergic” reactions may be non-immune mediated reactions to food, or positive allergy tests that do not correlate with clinical adverse effects. As such, a good laboratory test is needed to corroborate patient history.
Research indicates that some of the most popular laboratory diagnostic tests for food allergy, including skin prick testing, serum food-specific immunoglobulin E (IgE) determinations and atopy patch testing, have merit, but they require use and interpretation in the proper context.
“Much of the specific allergy testing isn’t that specific,” Eichenfield said. “There are problems with false negatives and, especially, with false positives.”
Many people with a positive result on a diagnostic test may never actually experience clinical symptoms of food allergy, such as anaphylaxis, urticartia, or other effects, Eichenfield said. He added that a positive serum IgE or skin prick is not the same as a positive food challenge. It is especially complicated in children with atopic dermatitis, who have a higher rate of true food allergy. When children test positive for IgE-sensitization to foods, it is often interpreted that the eczema is “caused by” food allergy, even though the tests may be false positive tests, and the elimination of food has impact on the course of dermatitis.
“From a practical standpoint, once you have identified someone with 20 positive tests, the damage is done and the patient winds up on an incredibly restrictive diet,” said Boyce. “What you do from there is damage control and trying to figure out what’s real and what can be safely introduced. So in the guidelines, we tried to make it very clear when one should and when one shouldn’t test.”
A patient’s medical history comprises a major component of this decision-making process.
Burks recommends asking the patient’s parent or the patient:
- “What type of symptoms are you having?”
- “How soon after ingesting the food do these symptoms appear?”
- “Do these symptoms occur reproducibly after ingestion of the food?”
- “Did it happen on more than one occasion?”
The guidelines also recommend that physicians consider testing for food allergy in children with certain disorders, such as eosinophilic esophagitis, moderate to severe atopic dermatitis, enterocolitis and allergic proctocolitis, as well as in adults with eosinophilic esophagitis.
The expert panel also noted that food elimination from a patient’s diet may help confirm a diagnosis.
Treatment, management strategies
The cornerstone of food allergy management is avoidance. Although the concept is simple, figuring out whether products contain a certain food can be complicated.
The Food Allergen Labeling and Consumer Protection Act has somewhat alleviated this burden by mandating that all major allergens be clearly identified on a product’s label, yet these standards are not a catch-all.
“Avoidance has to be coupled with good education on food labeling,” said Fenton. “People have to know how to read a food label, how to know the different words that mean the same thing in terms of food ingredients, and they must be aware of tricky labeling, such as ‘may contain trace amounts of…’.”
Parents and patients need to remain vigilant about various situations that might put them at risk for exposure to certain foods or places where cross-contamination of foods can occur, such as buffets or ice cream parlors.
Another important aspect of managing food allergies is remaining prepared for reactions.
“We have to teach patients and parents how to recognize early signs that they are having an allergic reaction,” said Sampson. “We also have to provide them with a medical plan and emergency medicine, such as epinephrine, to initiate therapy if they should have an accidental ingestion.”
Management for infants, however, is a trickier issue. The guidelines recommend breast-feeding and delaying the introduction of solid foods until 4 to 6 months of age as the best options, but they also note that hydrolyzed formulas may be beneficial if exclusive breast-feeding is not possible. Nevertheless, these formulas may be more expensive and more difficult to find, said panel members.
The guidelines also do not advise restricting maternal diet during pregnancy or breast-feeding as a way of reducing food allergy. Research in this area yielded conflicting results, according to the published data, and there is insufficient evidence to support that maternal diet has an influence on food allergy in children.
Although no FDA-approved treatment for food allergy exists, oral immunotherapy and sublingual immunotherapy drummed up discussion during the guidelines’ drafting process as some physicians believe they hold promise. The guidelines, however, currently recommend against using these treatments because of the lack of information on their safety.
“Food desensitization is really in its infancy,” said Boyce. “The studies are small but have been largely positive, but we’ve tried to make it very clear in this document that it is not yet ready for prime time.”
The panel also recommends against subcutaneous immunotherapy because some studies have linked significant health problems to this form of treatment.
Collaborative effort, broad scope
In 2007, the American Academy of Allergy, Asthma and Immunology and a patient advocacy group, Food Allergy and Anaphylaxis Network, approached NIAID and asked them to undertake the project of establishing clinical practice guidelines for food allergy.
“AAAAI had come up with their set of guidelines, ‘Food allergy: a practice parameter,’ in 2006, but it was very technical and very much written by allergists for allergists, and it wasn’t really seen outside the allergy community,” said Fenton.
After meeting with representatives from more 30 different organizations in 2007, the consensus was that the clinical community sees patients who have food allergy, not just allergists. “Everyone felt that there was a need for guidelines that could be used broadly across all clinical specialties,” he said.
NIAID assembled a coordinating committee, consisting of representatives from various lay and professional organizations, who in turn nominated and reviewed candidates for the expert panel from numerous specialties, including allergy, immunology, pediatrics, family medicine, gastroenterology, emergency medicine, dermatology and others, said Eichenfield.
After the panel generated topics to direct the research, the RAND Corporation reviewed more than 12,000 articles on food allergy and presented the results that formed the basis for the guidelines.
“For some of the areas, the data are spotty, so not all of the recommendations are based on strong scientific evidence,” said Boyce. He explained that some of the guidelines supported by weaker evidence may have had greater contribution from expert opinion and pointed out that the level of evidence for each recommendation is marked in the document.
After a draft was completed, the guidelines also underwent a public comment period during which patients, families and health care professionals provided input. Because these recommendations were created for use by such a broad set of physicians, the public comment period was valuable, said Sampson.
“Some of the things we thought we’d explained pretty clearly didn’t come across as clearly as we’d thought, so it gave us an opportunity to alter that and hopefully make it more useful.”
A “family- and patient-friendly synopsis” of the guidelines was also developed in parallel with the document itself. This version is not simply a translation, according to Fenton, but offers information about what parents or patients should monitor in themselves or their children to develop a good patient or family history; what options are available to them; and what questions they should be asking their physicians.
Both the synopsis and the guidelines will be available and freely accessible through NIAID’s website (www.niaid.nih.gov) starting in late fall. Print copies may also be requested from NIH.
“We’re also working with the 34 organizations that collaborated with us on the project to get the information to these societies, patient advocacy groups and other federal agencies to put on their websites or have an executive summary included in their publications,” said Fenton.
The full set of guidelines will also be published as a print supplement to the Journal of Allergy and Clinical Immunology in December.
Implications for practitioners
One of the expert panel’s major goals in creating the guidelines was standardizing the way that physicians approached food allergy. However, better recognition of symptoms and understanding how best to use diagnostic techniques are only a few pieces of the puzzle. Knowing the natural history of the disease is also key.
“There’s a higher prevalence of food allergy in childhood and then it begins to go down as you reach adulthood,” said Burks. “Follow-up is really important because we know there are certain foods that you’re more likely to outgrow earlier, in the first decade or so of life, and we know there are foods that you’re less likely to outgrow but still can.”
Food allergies, such as milk and egg, are among those pediatric patients are most likely to leave behind as they age. But how does a physician know when retesting is appropriate?
The guidelines suggest follow-up testing and note that annual intervals are common for allergies to milk, egg, wheat and soy. The guidelines’ authors note that 2- to 3-year periods between testing are generally used for peanut, tree nut, fish and crustacean shellfish allergies. No hard scientific data, however, support these time frames.
Although the guidelines are meant for use by all physicians, they note that there are occasions when some patients need to see an allergist, such as cases when certain diagnostic tests need to be performed or if a patient has experienced serious symptoms, such as anaphylaxis.
The guidelines also aim to help physicians with another responsibility: reducing the fear factor.
“Many patients self-report food allergy to their physician only to find out that they don’t have food allergy. The guidelines use hard data to show that the actual rates of food allergy are rather low, thus helping the patient to decrease their anxiety,” said Fenton. “Using the guidelines, physicians and their patients can work to identify what is really the cause of the problem and treat it accordingly.”
Basic questions, new research
While the guidelines have been a first step toward creating better awareness and understanding of food allergy, more work needs to be done.
Many of the initial questions still have no answers, said Fenton. Investigation into prevalence; triggers and risk factors for food allergy; and why severe allergic reactions occur in some patients while not in others is lacking.
Sampson noted one significant trend in the current research. “It’s really the Westernized, industrialized countries where we’ve seen the biggest increase,” he said.
He cited studies demonstrating the higher prevalence of peanut allergy in certain countries, such as the United States, Canada, the United Kingdom, France, Germany, Italy, Australia and New Zealand.
The condition remains virtually nonexistent in China, although its population consumes the same amount of peanuts per capita as people in the United States. “We believe it’s something to do with our lifestyle, but we don’t know what it is,” Sampson said.
Ideas are abundant — the hygiene hypothesis; loss of protective infections, such as measles and hepatitis A, resulting from vaccination programs; and increased exposure to a variety of different foods are just a few theories for why allergy rates have gone up, said Boyce. Current data, however, are not yet robust enough to pinpoint any one underlying physiological cause.
The most important research goals in the short-term pertain to diagnostic testing and therapy.
“We would like to not have to resort to food challenges, and we would like to come up with some form of treatment that would be safe and practical,” said Sampson.
He also noted that many scientific areas need further exploration, such as why people develop tolerance to certain foods or why foods with similar compositions, like peanuts and soybeans, may cause different levels of allergic reaction.
Research into prevention, including early life introduction of foods, will also be important in the future, said Boyce. – by Melissa Foster
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