By Scott Sicherer, MD
I had not seen the family in my allergy practice for over a year. When I last saw them I had suggested that we perform physician supervised oral food challenges to egg and almond. When I asked the family why they had not scheduled these tests, they said that they were not interested. “How could you not be interested in adding egg to your diet?”, I asked, “It’s in so many foods!”. “Well, we didn’t really think we had that great of a chance of passing the test and were worried about an allergic reaction”, answered the mother. My eight-year-old patient chimed in with “And I don’t like almond”. “How do you know you don’t like it if you never had it?” her mother asked. I knew we had missed something on our previous visit and needed to have more discussions about oral food challenges.
When an allergist diagnoses a food allergy, she combines information regarding the patient’s past history with the food, overall allergy status, knowledge about the characteristics of allergy for the food in question, and test results such as skin and blood tests. In many cases, these important aspects of a food allergy evaluation do not provide a definitive diagnosis. In that case, the primary test that can most clearly identify whether an allergy exists is the physician supervised “oral food challenge” or feeding test.
The oral food challenge test really reflects the idiom “the proof is in the pudding”. The food in question is fed in gradually increasing doses until an adequate amount is ingested to conclude there is no allergy, or the feeding is stopped if there are any signs of an allergic reaction, diagnosing a current allergy. If the food is tolerated, then it is typically fine to incorporate into the diet. The test is most often offered in a clinical setting when there are reasonable odds that the food would be tolerated and the family/patient are motivated to add the food to the diet. The procedure takes several hours. The procedure is not designed to determine how severe an allergy is, because the feeding is stopped at the first sign of any reaction.
Another setting in which an oral food challenge is performed is for research. In this case, unlike for diagnostic purposes, the test might be applied to an individual who is likely allergic, to confirm they are truly allergic and how much of the food they can have prior to an allergic reaction. This is typically done in the beginning and at the close of a treatment trial to see if the treatment made a difference. Even when food challenges are undertaken for research purposes in those who are likely allergic, it is considered a very safe procedure and severe reactions are very uncommon.
Anxiety about an allergic reaction is a real problem in interpreting these tests. A person may complain of various symptoms because they are worried and know they are eating the food they have been avoiding. For this reason, particularly for research purposes, the test is done by hiding the food in question in a way that it cannot be detected and the individual is fed either the real food or a placebo at different times to try to reduce the impact of anxiety. This “gold standard” test is called a double-blind, placebo-controlled food challenge.
However, most oral food challenges are performed to foods for clinical reasons. Like my patient above, a family needs to agree that it makes sense for them to undergo the test. The issues that a physician and family may consider would include the chance of passing, the nature of allergic reaction that the test might provoke, the importance of the food to the diet, and nutrition, social, emotional and a number of other factors.
Although the risks and benefits are always discussed, I noticed that many times families did not undergo the test that was offered it was not always clear why they made that decision. To get a better idea of why many families would defer an oral food challenge, we conducted a study in which 102 families described why they had not undertaken an offered oral food challenge to a total of 183 foods. Many families identified scheduling issues because the procedure requires at least one half-day. However, when it came to issues other than schedules, a number of important areas of concern were identified.
The category with the biggest impact, chosen by 57%, was that the food was not that important or was impractical to the diet. Issues include picky eaters, the child not thinking food was important, other family members with the allergy, or concerns about cross-contamination making the food impractical. It is important to discuss these issues because a more thorough discussion could disclose answers to these concerns that might change opinions. For example, my patient described above did not realize that they would have options such as Honey nut Cheerios, almond butter, and almond milk that they would be interested in. There are also ways to manage picky eating and advancing the diet could be a very practical way of increasing options.
Forty percent of the time individuals responded about fear or emotional impact, for example, worries about having an allergic reaction during the test or becoming more fearful of foods. It is important for families, patients and allergists to discuss these risks. While severe anaphylaxis is a possibility, the chance of this happening is reduced with gradual feeding and with selection of foods that are overall more favorable to be tolerated. The most common symptoms are skin symptoms or stomach symptoms if there is an allergic reaction. Most reactions are treated with antihistamines, relatively few require epinephrine. When epinephrine is needed, this is an opportunity to see how safe and effective this treatment is. Overall, of course, most tests do not induce any symptoms. No fatalities from medically supervised oral food challenges have been reported.
Regarding the emotional impact, an individual’s personality is important to consider. For some families and children the thought of ingesting the food that has been taboo and a risk can be very daunting. From an emotional perspective, having an allergic reaction could on the one hand be empowering for some children in learning what it is like and how it is managed, while for others it could potentially increase their anxiety. Studies have suggested that oral food challenges can improve quality of life whether or not the food turns out to be tolerated. However, prior to the procedure, for some individuals, evaluation by mental health specialist may be very helpful.
Additional reasons that families indicated for not undergoing a food challenge that was offered to them included their opinion that they were allergic and did not need the additional test, that a reaction could worsen the allergy, or that the child is too young. These concerns clearly emphasize the importance of a thorough discussion. Sometimes families self-interpret tests, not realizing that often tests are positive but the food may be tolerated, or that a specific “number” on a test is interpreted differently for different foods or different age groups. The allergist can likely provide very good estimates of the likelihood of allergy so that the family can make informed decisions. There is no evidence that a failed oral food challenge worsens an allergy or changes its natural course. Lastly, this can be done at any age. Let’s consider a situation where based on the past history and tests the chance of a reaction to peanut is 80%. Well, the family of a 4 year old might rightly defer this test. However, the 20% odds of “passing” may make a lot of sense for undergoing the feeding test for a teenager about to embark on having more independence into adulthood.
The most worrisome answer that we found on the survey was that the family had tried the food on their own, rather than scheduling a supervised feeding. Worse, half of them actually reacted. When an allergist is offering a physician-supervised oral food challenge, they are doing it because they are estimating some risk of a reaction and it makes sense for a gradual feeding under medical supervision so that interventions are immediately available under expert guidance. The lesson: don’t try the test on your own at home!
In summary, the study demonstrated the likely importance of a very deliberate and detailed discussion about the risks and benefits of the test, addressing biases such as considering whether food is important or not and issues about risk and fear of reactions. Patients should have lots of questions, and their doctors should be prepared to answer them. Education about the safety of the test, risks, benefits, nutritional issues, social and emotional aspects should be included in the discussion. This test has the potential to expand the diet, improve quality of life and nutrition, and teach lessons about managing allergic reactions. Food allergic life has enough uncertainties. Addressing reasons to undergo or forego the test is key.
Scott H. Sicherer, MD is the Elliot and Roslyn Jaffe Professor of Pediatrics, Allergy and Immunology and Chief of the Division of Allergy and Immunology in the Department of Pediatrics. He is Medical Director of the Clinical Research Center, a component of Conduits-the Institutes for Translational Sciences at Icahn School of Medicine at Mount Sinai. Dr. Sicherer is a clinician and clinical researcher in the Jaffe Food Allergy Institute at Mount Sinai. He is also the author of Food Allergies: A Complete Guide for Eating When Your Life Depends On It.