Ronald A. Simon, MD, often illustrates a major food allergy misconception by showing a “Peanuts” cartoon of a bleary-eyed Snoopy lying atop his doghouse. “I think I’m allergic to morning,” Snoopy says.
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March 2011Dr. Simon, head of the Allergy, Asthma and Immunology Division at the Scripps Clinic in La Jolla, Calif., said many patients tend to blame a dislike or intolerance on an allergy. In fact, research suggests that the positive predictive value of self-reported food allergies is strikingly poor. As a panelist and co-author of the National Institute of Allergy and Infectious Diseases’ (NIAID) first-ever guidelines on food allergies, Dr. Simon hopes the new document will better educate both doctors and patients about a medical condition that is still plagued by sizeable gaps in knowledge.
The guidelines, published in December in the Journal of Allergy and Clinical Immunology (126(6,):S1-S58), are based on an extensive literature review and the opinions of a 25-member expert panel. The document begins with a definition of food allergy and offers 43 recommendations on its diagnosis and management. Throughout the report, however, the authors point out multiple areas with low-quality evidence where further research could significantly change the recommendations.
The panel’s straightforward approach and acknowledgment of deficiencies has won praise from many other otolaryngologists. “I think it is a call for research and for people to fill in those knowledge gaps,” said Elizabeth Mahoney, MD, an assistant professor of otolaryngology-head and neck surgery at Boston University Medical Center. “From my standpoint, it’s a good launch pad for additional research and helps us to streamline our efforts so that people have more uniform practices.”
Karen Calhoun, MD, professor of otolaryngology-head and neck surgery at the Ohio State University Medical Center in Columbus, also gave the guidelines high marks. “The whole document is excellent, beautifully researched with clear data summaries and recommendations,” said Dr. Calhoun, chair of the American Academy of Otolaryngology-Head and Neck Surgery Allergy, Asthma, and Immunology Committee.
Bruce Gordon, MD, an otolaryngologist based in Hyannis, Mass., was less impressed. “The guidelines were a rehash of material previously available, and so they are only useful as a convenient summary, and, perhaps, for education of clinicians who are not often involved with care of food-allergic people,” he said.
Of the guidelines deemed most useful, the otolaryngologists who spoke with ENT Today highlighted recommendations on introducing foods to infants, administering vaccines to people with egg allergies, treating acute cases and diagnosing patients.
Infants
“In terms of introducing infants to foods, you have to take it all the way back to pregnancy,” said William Reisacher, MD, assistant professor of otorhinolaryngology and director of The Allergy Center within the department of otorhinolaryngology at Weill Cornell Medical College/New York-Presbyterian Hospital. “Mothers are concerned: If they have a family history of food allergies, should they be consuming certain foods during their pregnancy? Then what should they do in terms of breastfeeding? Is that beneficial at all? And then when do you actually introduce the foods? Do you test the child before you introduce the foods?”
In a departure from past recommendations, the panel concluded that there was insufficient evidence to suggest that women should restrict their diet while pregnant or nursing (Guideline 36). “I think that takes a big load off the minds of parents, particularly those who have food allergy in the family,” Dr. Reisacher said.
Perhaps even more noteworthy to many otolaryngologists was the recommendation that “introduction of solid foods should not be delayed beyond 4 to 6 months of age,” including the introduction of potentially allergenic foods (Guideline 40). “The prior thinking was that you had to withhold milk for a year, eggs for two years, and nuts and seafood for three years, and now they’re saying that there’s really no reason to withhold anything beyond four to six months,” Dr. Reisacher said.
“That’s a very big change in what was advised previously,” said Dr. Mahoney, who noted that the new recommendations are in agreement with the American Academy of Pediatrics’ (AAP) own recently revised guidelines (Pediatrics. 2008;121(1):183-91).
Dr. Simon said the major revision has come as the result of some surprising new research. “There’s some data suggesting that we may have completely missed the boat on this one, and that potentially earlier introduction of food may actually be a good idea,” he said. “At that point, the infant’s immune system is very, very underdeveloped, and it may accept the food and get tolerant to it, whereas if you wait longer, when the immune system has really matured, that’s when it’s going to see it as something foreign and then develop the allergy. So we may have had this really backwards.”
Vaccines
The guidelines include another change in the recommendations on which vaccines grown in chick embryos can be safely administered to patients with a history of severe reactions to egg protein (Guideline 31). The recommendation on administering flu vaccine is less clear-cut than that of other vaccines, reflecting both a lack of firm evidence and the observation that “egg allergy is relatively common among the very patients who would highly benefit from influenza vaccination,” according to the document.
“A huge problem that we have, particularly with the flu epidemic and H1N1, is people coming in who have had sensitivities and reactions to egg not knowing whether or not they should receive a flu shot,” Dr. Reisacher said. In issuing some guidance, he said the latest recommendations by the NIAID are somewhat less conservative than previous advice from the American Academy of Pediatrics.”
According to the AAP, the vaccine shouldn’t be given if there have been any severe reactions to egg, like hives, angioedema, asthma and anaphylaxis, but can be given to patients who have had a less severe reaction to egg. “The organization here in the paper said that there is some further evaluation that can be done, and if the amount of egg protein is less than a certain amount in the vaccine, even if a person has had a very severe reaction, there’s no evidence to support withholding that injection, that it’s safer to give that injection,” Dr. Reisacher said.
In some commercial flu shots, Dr. Simon said, researchers have had trouble detecting more than a trace of egg protein, “so it was always more of a theoretical risk than it was an absolute risk.” Recent studies suggest that very highly egg-allergic patients can safely receive the flu shot, though more research will be needed to verify the findings. “People thought that it might not be a problem, but it’s always nice to have the data,” he said.
Dr. Simon said studies published after the guidelines were reviewed are bolstering the idea that the flu vaccine is safe. For one protocol, clinicians administer one-tenth of the dose, wait 30 minutes and then give the other nine-tenths (Ann Allergy Asthma Immunol. 2010;105(5):387-393). That approach, he said, has proven so safe that his group and collaborators at the Mayo Clinic are conducting a study that involves “simply giving the whole dose, even in severe egg allergic subjects.”
Life-Threatening Conditions
Dr. Calhoun pointed to a separate guideline on treating acute, life-threatening, food-induced allergic reactions (Guideline 42) as one of the most important. “Epinephrine is the first-line treatment in all cases of anaphylaxis,” the guideline states. “All other drugs have a delayed onset of action.”
Dr. Calhoun said the importance of this guideline is underscored by its summary: “The use of antihistamines is the most common reported reason for not using epinephrine and many place a patient at significantly increased risk for progression toward a life-threatening reaction.”
She explained that when a patient develops early signs of anaphylaxis, a physician may hope that an oral antihistamine treatment will suffice and that something as ‘extreme’ as an epinephrine injection isn’t needed. “But the oral medication is absorbed slowly, and the reaction progresses,” she said. “The further it progresses before giving the epinephrine, the harder it is to control. So the message is: Use epinephrine first for a systemic anaphylactic reaction.”
Testing
Several otolaryngologists agreed that other guidelines referencing specific diagnostic methods, including skin prick testing, allergen-specific serum IgE testing and oral food challenges, are also particularly useful from a clinical standpoint and may cause some physicians to alter their practice (Guidelines 4, 5, 7 and 11).
The expert panel endorsed both skin prick testing and specific IgE testing for identifying foods that may be provoking an allergic reaction. The guidelines concede, however, that neither test on its own is sufficient to diagnose a clinically significant food allergy. Rather, Dr. Calhoun said, the results must be correlated with the patient’s clinical history, and, in some cases, a supervised food challenge.
Dr. Mahoney and Dr. Reisacher concurred that the recommendations do a good job emphasizing the need to test rather than rely on a patient’s self-reporting, and recognizing that skin prick and specific IgE testing require prudence and follow up because of their high rate of false positive results.
The information itself may not be new, but Dr. Reisacher said the guidelines’ comprehensive summary and categorization should help doctors better organize their approach. Perhaps most of all, he said, the document offers a benchmark for a field with many unanswered questions. “I think the biggest benefit to the guidelines is really making us realize how far we still have to go concerning food allergies, on their diagnosis and management.”
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