Real-world factors predict tolerance in oral food challenges
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Key takeaways:
- 76.1% of patients tolerated the oral food challenge, including 53% of high-risk patients.
- Patients with histories of respiratory symptoms were more likely to tolerate the challenge.
Several factors may indicate whether a patient may tolerate an oral food challenge, including patients who may be considered high risk for reactions, according to a study published in Annals of Allergy, Asthma and Immunology.
The real-world study also found that most patients tolerated the food and few reactions required epinephrine, the researchers wrote.
“We wanted to systematically review real-world experience with oral food challenges in our practice over the past 3 years,” S. Shahzad Mustafa, MD, lead physician in allergy, immunology and rheumatology at Rochester Regional Health, told Healio.
“Our practice does a lot of food challenges, and our experience is unique compared to food allergy referral centers,” Allison C. Ramsey, MD, clinical assistant professor of medicine, University of Rochester School of Medicine and Dentistry, also told Healio. “We wished to describe this.”
Study design, results
The single-center study involved 1,132 OFCs performed at three allergy/immunology outpatient office locations in urban and suburban settings that were not physically connected with any inpatient facility, which the researchers called unique compared with previous studies on OFC outcomes.
OFCs were administered at a median age of 4 years (interquartile range [IQR], 2-10), although 97 (8.6%) of the OFCs were performed on adults. Initial food allergy diagnoses occurred at a median age of 1 year (IQR, 0.8-2), with a median of 3 years (IQR, 1-6.5) passing since the initial food allergy reaction.
Results included 862 (76.1%) patients who tolerated the food, 232 (20.5%) who had a reaction and 38 (3.4%) did not complete the challenge due to food refusal. Tolerated foods included shellfish (91.1%), baked milk (88.5%), tree nuts (85.8%) and egg (84.8%).
Foods with the lowest tolerance rates included baked egg (66.1%), sesame (67.7%), wheat (68.8%) and peanut (69.1%).
Among the 66 (5.8%) OFCs that were high risk for milk, egg and peanut, 35 (53%) tolerated the food, including nine of 15 (60%) who tolerated milk, 15 of 25 (60%) who tolerated egg and 11 of 26 (42.3%) who tolerated peanut.
The patients who experienced reactions included 70 (30.2%) who had symptoms after the first dose, 52 (22.4%) after the second dose and 24 (10.2%) who did not react until the sixth and final dose.
Common reactions included urticaria/angioedema in 110 (47.4%) OFCs, rashes in 43 (18.5%), anaphylaxis in 32 (13.8%) and respiratory symptoms including cough, wheezing or dyspnea in four (1.7%).
Treatments for the reactions overall included antihistamine alone (n = 126; 54.3%), a single dose of epinephrine with or without an antihistamine (n = 61; 26.2%), or two doses of epinephrine (n = 7; 3%). Also, symptoms resolved for 38 (16.4%) OFCs without any medical intervention.
None of the patients required a third dose of epinephrine. Three patients were transferred to an ED for further monitoring, but none of them required additional treatment.
Patients who had an OFC to facilitate the introduction of a food had higher odds for tolerating the food than patients who had an OFC to confirm or refute a diagnosis of food allergy (OR = 19.46; 95% CI, 10.74-39.13).
Specifically, patients who had an OFC to facilitate food introduction had higher odds for tolerance than patients who were confirming or refuting a baked milk or baked egg diagnosis (OR = 4.35; 95% CI, 2.24-9.19) or to evaluate the resolution of an allergy (OR = 3.06; 95% CI, 1.61-6.36).
The researchers said they did not find any differences in odds for tolerating an OFC to confirm or refute a diagnosis of food allergy, baked milk or baked egg OFC, or an OFC used to document food allergy resolution.
OFCs conducted due to histories of respiratory symptoms were 5.6 times more likely to be tolerated than OFCs conducted based on histories of rash and/or pruritis (95% CI, 1.1-137.32).
Further, patients who were diagnosed based on testing alone or who were avoiding tree nuts due to a peanut allergy were more likely to tolerate an OFC than those patients who were avoiding foods due to clinical histories of rash/pruritis, urticaria and/or angioedema or anaphylaxis.
Patients who were older when they were diagnosed (P = .004) or who were older at the time of the OFC (P = .002) were more likely to tolerate the OFC, and those with a comorbid history of peanut allergy (OR = 0.64; 95% CI, 0.47-0.87) were less likely to tolerate it.
Other indicators of greater odds for tolerance included smaller skin prick test wheals (P = .001), SPT flares (P .001) and food-specific IgE at the time of diagnosis (P = .01) in addition to smaller SPT wheals (P < .001), SPT flares (P < .001) and food-specific IgE at the time of the OFC (P < .001).
Conclusions, next steps
Noting that OFCs are underutilized in clinical practice despite their usefulness and beneficial impacts on quality of life, the researchers said their findings demonstrating the safe conduct of OFCs including a 76.1% tolerance rate at an outpatient office location should encourage their use in managing food allergies.
“We were surprised by the rate of individuals tolerating ‘high risk’ food challenges for cow’s milk, egg and peanut,” Mustafa said.
Despite unfavorable testing criteria including significant skin testing reactivity and highly elevated food specific IgE, more than half of these patients tolerated the food, further emphasizing the importance of clinical history as opposed to diagnostic testing alone in making an accurate diagnosis of food allergy, he continued.
Ramsey agreed.
“We should be considering the patient’s entire clinical picture when deciding upon a challenge, not just the objective skin/blood work data, because we showed that patients passed food challenges sometimes even if their testing suggested they would not,” Ramsey, who also is a member of the Healio Allergy/Asthma Peer Perspective Board, said.
“The safety of challenges should also be emphasized when they are conducted in a monitored setting such as ours,” she continued.
Ramsey also noted that a few large academic centers publish their research on food allergy.
“It is helpful to have a different perspective from our experience, which is high volume with less of a food allergy center referral bias,” Ramsey said.
Mustafa and Ramsey both said that allergists should offer more food challenges.
“It is easy to lose sight of how difficult food avoidance is, and challenges can confirm if this strict avoidance is necessary or unnecessary,” Ramsey said.
“We hope our results encourage other allergists to offer oral food challenges when the diagnosis of food allergy is uncertain, even when skin test and blood work results may be unfavorable,” Mustafa said.
For more information:
S. Shahzad Mustafa, MD, can be reached at shahzad.mustafa@rochesterregional.org. Allison C. Ramsey, MD, can be reached at allison.ramsey@rochesterregional.org.
Perspective
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This is an interesting article with valuable information and findings. I do not find the success rates of the OFCs surprising as it is comparable with my own experience. What I do find surprising and concerning is vast underutilization of OFCs given it is promoted as the gold standard of diagnosis for food allergy and well-proven quality of life benefits.
I was surprised that only one to five OFCs per month are offered and 56% of allergy/immunology fellows reported conducting fewer than 10 OFCs in training, with 29% reporting not having conducted any. If that is the gold standard for diagnosis, then why are the academic institutions not implementing more? How can allergists entering clinical practice be expected to then offer them to their patients?
If doctors are not comfortable or properly trained in doing OFCs, then they should consider increasing their skillset by taking courses or attending conferences that provide education and resources for them to do OFCs in their practice. This can greatly enhance our services to patients. I understand there are logistical issues in a busy clinical practice as well as risk for the patient. But the risk of not doing OFCs can be detrimental to patients and their families.
Many doctors do not understand food allergy tests. This article shows some of the limitations with current validated tests where 53% of “high-risk” patients passed an OFC. Additionally, this does not account for the vast array of nonvalidated tests that are used and marketed so heavily.
There is nuance to ordering proper food allergy tests and interpreting the results. It has been recommended for years that broad food allergy panels not be ordered as the predictive value in that case is low. Despite this, doctors continue to order these tests in broad panels. When many come back positive, they often will not know what to do in that case, so they have patients avoid the foods.
Patients are frequently told to avoid the foods, even if they were previously tolerating them. Unnecessary food avoidance can lead to increased stress and anxiety on a family and the patient. Sometimes, there are negative impacts of restricted calorie diets in children as well.
In this case, OFCs are the current answer to determine if the tests are true or false positives. It is a method of safely getting foods in question back into the diet of patients. However, when OFCs are not being performed, then patients will continue to avoid foods, oftentimes unnecessarily. That puts them at more risk for anxiety, nutritional deficits and developing the allergies.
There are some tests in clinical practice, such as basophil activation tests (BAT) that are similar to doing an OFC, but in a test tube. I have been utilizing BAT in clinical practice for the last 3 years so that I could get more information on patients prior to an OFC and also in monitoring of food allergy treatments. Making these types of tests more clinically available may alleviate the burdens of OFCs in busy clinical practices and reduce the risks to patients.
While there are still some challenges with implementation and usage of BAT in clinical practice, it has been helpful in my practice in providing more in-depth clues to the patient’s diagnosis and how to more selectively choose who may be in need of an OFC. Surprisingly, BAT provides valuable information for those embarking on food allergy treatment, not only in the diagnostic phase, but also in the monitoring phase of those who have undergone oral immunotherapy or sublingual immunotherapy to food.
In my practical experience, I had a cohort of Australian families travel to my clinic in the United States prior to the pandemic seeking food allergy treatment. Australia is often nicknamed the food allergy capital of the world. Actual treatment options have been largely absent outside of the research setting, but families are desperate after having been told to avoid so many foods. Additionally, OFCs are of limited availability.
In my group, 31 of 36 patients needed OFCs prior to starting OIT as a food allergy treatment. In those 31 patients, we conducted a total of 230 OFCs; 216 foods were passed, and 14 foods required treatment. Even before starting OIT, we were able to get 216 foods back into the diets of these 31 patients. Out of the 36 patients, 116 foods were successfully treated at a 92% success rate. In summary, by utilizing both OFCs and OIT in 36 patients, we were able to get 332 foods back into their diets.
References:
Bourgoin P, et al. J Allergy Clin Immunol Pract. 2023;doi:10.1016/j.jaip.2023.08.029.
Charpy J, et al. Clin Exp Allergy. 2023;doi:10.1111/cea.14363.
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