Email: info@allergy.org.au
Website: https://allergy.org.au

©2022 Australasian Society of Clinical Immunology and Allergy (ASCIA)
ABN 45 615 521 452

 

Position Paper - Oral Food Allergen Challenges

pdfASCIA HP Food Allergen Challenges 2022163.8 KB

Oral food allergen challenges are standardised procedures where incremental amounts of a particular food are fed to a patient, usually over a period of two to three hours. This does not involve testing the food on skin.

The patient is monitored to determine if the food being tested causes an allergic reaction, and observed for a minimum of one hour after the last dose or reaction. Observation can be longer (two to four hours), depending on the clinical situation and food being challenged.

Oral food allergen challenges are performed under medical supervision by a clinical immunology/allergy specialist or an experienced paediatrician or physician with postgraduate allergy training.

They generally involve nursing support staff and take place in a clinic with immediate access to emergency treatment for a severe allergic reaction (anaphylaxis).

Clinical justification for oral food allergen challenges

Food allergy is common, with prevalence of around 5% in children and 2% in adults. The most common food allergens are egg, cow's milk, peanut, tree nuts, sesame, soy, fish, shellfish and wheat. Currently the only treatment is avoidance of the food/s.

Peanut, tree nut, seed and seafood allergies are much less likely to be outgrown and can be lifelong allergies.

Severity of allergic reactions to foods cannot be predicted, so people with food allergy and their carers need to:

Oral food allergen challenges are regarded as the gold standard procedures for the diagnosis of food allergy, are standard of care in managing food allergy, and appear in practice guidelines worldwide.

Oral food allergen challenges are medical procedures that are mainly used to determine if a person with:

Oral food allergen challenges play a pivotal role in ongoing management of food allergies for the following reasons:

Other tests for food allergies

In people with food allergies, immunoglobulin E (IgE) antibodies to allergens are usually raised. This is why immediate type allergies (which can result in anaphylaxis), are called IgE mediated allergies.

Whilst food allergy testing using skin prick tests (SPT) or blood tests for allergen specific IgE (ssIgE) may be used in conjunction with oral food allergen challenges, they are not considered as substitute tests for challenges, as they are significantly less accurate.

A positive food allergy test using SPT or blood tests means that a patient’s immune system has produced an antibody response to that food, known as being sensitised to an allergen:

For the reasons stated above, it is important in some circumstances to confirm the significance of a positive (or negative) allergy test with an oral food allergen challenge, to prevent unnecessary avoidance of food and unnecessary prescription of adrenaline autoinjectors.

Oral food allergen challenge protocols

ASCIA oral food allergen challenge protocols have been developed to provide standardised protocols used by clinical immunology/allergy specialists in Australia and New Zealand. The protocols are peer reviewed and based on expert opinion and published literature.

The ASCIA protocols are similar to published protocols used worldwide for food allergen challenges:

Most oral food allergen challenges require approximately two hours to eat the required doses of food, followed by a minimum one hour of observation (or longer if an allergic reaction occurs during the challenge):

Benefits of negative oral food allergen challenge results (without allergic reactions)

One of the main purposes of oral food allergen challenges is to ‘de-label’ patients by confirming that they no longer have a food allergy. This has significant effects on quality of life for the patient, their family and other carers, developmental implications, and cost savings.

For example, a negative oral food allergen challenge can result in:

After a negative result for an oral food allergen challenge, the challenge food/s needs to be regularly included in the diet (at least once a week) to maintain tolerance.

Some people who do not eat the food for long periods may become sensitised to the food and have allergic reactions again when they consume the food.

Benefits of positive oral food allergen challenge results (with allergic reactions)

If an allergic reaction occurs during the challenge it will be treated with medications (including adrenaline if indicated), and any other medical measures as needed.

It is also necessary for the patient to stay under medical supervision for at least four hours after the challenge.

Confirming a suspected food allergy is important for the following reasons:

Clinical management pathway for oral food allergen challenges

Oral food allergen challenges are conducted in clinics where resources are available to manage the risk of anaphylaxis, which requires emergency treatment and resuscitation facilities.

Reasons a patient may require a medically supervised oral food allergen challenge, due to medium to high risk or probability of allergic reactions, include:

Where the likelihood of a reaction is considered very high, based upon the clinical history and complementary allergy testing, a food challenge is deemed unnecessary, and the person is considered to be food allergic.

An oral food allergen challenge should not be conducted if a patient or their family does not intend to include the food regularly in the diet following a negative challenge, as this is a waste of resources,  irrespective of the likelihood of allergic reactions.

Oral food allergen challenge precautions

Oral food allergen challenges should only be used in:

If the patient being challenged has a prescribed adrenaline injector this should be brought to the food allergen challenge. If a severe allergic reaction occurs, it may be an opportunity for the person (if old enough and well enough), or parent to administer the adrenaline injector in a controlled setting.

Medical and nursing staff supervising the food challenge should always have a supply of adrenaline available even if the patient has their own adrenaline injector with them.

Current limitations of oral food allergen challenges

In Australia and New Zealand clinical immunology/allergy specialists work in public and private hospital clinics as well as private consulting rooms. Whilst oral food allergen challenges are currently routinely conducted in all of these settings, access is limited by several factors:

Improved access to food allergen challenges will be required to confirm the patient’s food allergy prior to new food allergy treatments, such as Oral Immunotherapy (OIT), which is already used in many countries. This will become a significant challenge once OIT is routinely available in Australia and New Zealand.

The introduction of a MBS item number or code for oral food allergen challenges to be conducted in private and hospital clinics would greatly assist in improving timely access to oral food allergen challenges, which are the gold standard tests for diagnosing food allergy.

Improved access to food allergen challenges will result in considerable improvements in quality of life and cost savings, mainly due to many patients who are de-labeled of their food allergy no longer needing to:

Summary of key points

Further information and support

References - Oral Food Allergen Challenges: www.allergy.org.au/hp/papers#p3

ASCIA patient information: www.allergy.org.au/patients/food-allergy

Patient support: Allergy & Anaphylaxis Australia www.allergyfacts.org.au; Allergy New Zealand www.allergy.org.nz

© ASCIA 2022

ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand.

ASCIA resources are based on published literature and expert review, however, they are not intended to replace medical advice. The content of ASCIA resources is not influenced by any commercial organisations.

For more information go to www.allergy.org.au

To donate to immunology/allergy research go to www.allergyimmunology.org.au