EAACI updates guidelines for diagnosing IgE-mediated food allergy
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Key takeaways:
- Diagnostics should begin with a thorough patient history.
- Testing may include skin prick tests, specific IgE and basophil activation tests.
- Children should be reassessed regularly.
The European Academy of Allergy and Clinical Immunology has updated its EAACI Guidelines on Food Allergy Diagnosis, targeting patients with IgE-mediated food allergies.
Published in Allergy, the update emphasizes the importance of clinical history, outlines when specific tests should be used and encourages regular reassessments, Alexandra F. Santos, MD, MSc, MRCPCH, FHEA, PhD, chair of the EAACI steering committee, and colleagues wrote.
“The last food allergy guidelines were published in 2014 and evidence was available urging an update of the recommendations,” Santos told Healio.
Since the previous update in 2014, developments in testing and technologies have enhanced the accuracy, efficiency and personalized treatment approaches in food allergy diagnostics, prompting the need for revisions.
Eight recommendations
There are three main changes to the previous update, Santos said.
First, the expert group that prepared the update recommended testing of specific IgE to allergen components for certain food allergies. Second, basophil activation tests (BATs) were included as recommended tests for specific food allergies, if available.
Finally, open oral food allergies are now considered as the reference standard for most clinical situations with double-blind placebo-controlled food challenges (DBPCFCs) reserved for equivocal cases and for research.
Specifically, Santos and her colleagues presented eight recommendations.
The first of their eight recommendations says that the first step of the diagnostic workup in patients with suspected IgE-mediated food allergy should be a detailed allergy-focused clinical history.
The expert group called clinical histories fundamental to food allergy diagnosis because they provide pre-test probabilities of disease that guide the selection and interpretation of subsequent diagnostic tests.
The guidelines list more than two dozen questions that clinicians should ask in taking the patient’s history, including age at symptom onset, type and severity of symptoms, suspected foods, possible cofactors, dietary history and family history of atopic disease.
Although the authors called the value of the clinical history undebatable, they cautioned that it may overestimate the presence of food allergy and that further testing is required for confirmation of the diagnosis.
In their second recommendation, the authors said the first-line tests for patients with a history of suspected IgE-mediated food allergy should be skin prick tests and/or serum sIgE.
However, the authors advised clinicians to consider patient-specific factors when interpreting the results of these tests due to, for example, differences in the diagnostic performances of specific tests between age groups.
Diagnostic cutoffs extrapolated from published studies also should be used with caution in clinical practice, guiding the interpretation of test results without being used as clear-cut decision points.
In their third recommendation, the authors specifically advised that patients with histories of suspected IgE-mediated allergies to peanut, hazelnut or cashew should be tested for sIgE to Ara H 2, Cor a 14 and Ana o 3 in addition to SPT and/or IgE to extracts.
Fourth, when patients have equivocal diagnoses of IgE-mediated allergy to peanut or sesame, the authors recommended BATs, which have demonstrated moderate sensitivity and high specificity.
Due to their higher costs compared with SPT and sIgE testing and their lack of accessibility in many clinical settings, the authors advised, BATs should be used in cases that remain equivocal after SPT and sIgE testing if they are available.
“The inclusion of specific IgE to allergen components and the basophil activation test will enable a greater precision of diagnosis for certain food allergies, reducing the need for oral food challenges in patients who are allergic,” Santos said.
In their fifth recommendation, the authors advised against the isolated use of IgG and IgG subclass tests in addition to other tests to diagnose suspected IgE-mediated food allergy, because they lack evidence or rigorous validation supporting their use.
Also, the authors said that unvalidated tests lack clinical relevance and carry significant risks, such as dietary restrictions associated with dietary compromise, increased costs and reduced quality of life, in addition to potential exposure to culprit allergens.
The sixth recommendation advised regular reassessment of children with food allergies based on age, the food and their history to identify possible spontaneous tolerance, particularly in early childhood for specific foods.
Some cow’s milk, egg, peanut, tree nut and sesame allergies resolve spontaneously in early childhood, and fish allergy may resolve by adolescence, the authors wrote, although probabilities of resolution change with age and with specific patient populations.
Regular assessment of adults, however, is less necessary because spontaneous resolution in adulthood is unlikely, the researchers continued, but new food allergies may develop among adults and older children and should be investigated.
Seventh, the authors recommended medically supervised OFCs to confirm or exclude food allergy among patients who have unclear diagnoses despite IgE sensitization tests.
OFCs may eliminate unnecessary food avoidance, nutritional deficiencies and food aversion, improving quality of life, the authors explained, with open OFCs recommended as routine challenges in specialist allergy clinical practices.
Some patients with negative challenges might not reintroduce the food into their diets, the authors continued, possibly due to psychological or other factors. Clinicians need to ensure that any food exclusions are based on a robust diagnostic pathway, the authors wrote, with close monitoring to ensure reintroduction.
“The recommendation of open rather than DBPCFC for most clinical situations will facilitate the performance of these tests as open food challenges are much more feasible and less expensive than DBPCFC,” Santos said.
Finally, the authors recommended DBPCFCs when open OFC outcomes are indeterminate. DBPCFCs, which the authors called the gold standard, also may be used in research studies.
These tests are time consuming and resource-intensive, the authors wrote, so they are preferrable when adverse reactions to foods likely are not immune mediated, when reported symptoms are nonspecific or difficult to evaluate, or for very anxious patients.
Next steps
The authors called the dissemination and implementation of these updates crucial in ensuring the prompt identification of food allergy and optimization of the care of patients living with this disease.
Next, the authors said that they will update the EAACI Guidelines on Management of IgE-mediated Food Allergy by 2028, or earlier if important evidence emerges. The authors also called for additional research in food allergy diagnosis.
For example, the authors recommended the creation of diagnostic algorithms for primary care based on clinical history as well as the identification of new allergens in foods with an assessment of their diagnostic utility.
The authors also recommended the collection of additional data on the diagnostic performance of epitope profiling and on the BAT, particularly for foods other than peanut and sesame.
Further, the authors said that the utility of the BAT and other biomarkers should be validated in predicting the severity and threshold of allergic reactions. Finally, they said that the diagnostic performance of tests in patient populations of different ages, ethnicities and geographical locations should be determined.
In the meanwhile, physicians can begin using these guidelines in all clinical settings, Santos said.
“Doctors may want to review the cutoffs and how they apply to their clinical practice and also review their access to specific diagnostic tests and to request their access if the tests are relevant to their patient population, namely specific IgE to allergen components and the basophil activation test,” she said.
Reference:
For more information:
Alexandra F. Santos, MD, MSc, MRCPCH, FHEA, PhD, can be reached at alexandra.santos@kcl.ac.uk.
Perspective
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Aikaterini (Katherine) Anagnostou, MD (Hons), MSc, PhD
Food-allergic individuals and their families face multiple challenges following their diagnosis, including dietary limitations and potential nutritional deficiencies, social restrictions, emotional burden and increased health-related costs.
A correct diagnosis of food allergy is key, but not always straightforward. The recently updated EAACI guidelines outline some important steps in the diagnostic process, with history-taking at the forefront of clinical practice. New testing modalities, in addition to existing, traditional methods, will hopefully enhance the accuracy of diagnosis.
Patients will need to be involved in discussions about the use of different tools and their role in diagnosing food allergy, with shared decision-making leading to the right choice for each individual. OFCs remain the gold standard diagnostic tool when there is doubt about the presence of food allergy.
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