When it comes to food allergy diagnosis, most of us think of blood tests for general or allergen specific IgE levels. In my presentation at MEDICA, I was keen to explain why blood tests and finger prick tests should only be the first stage in screening for food allergies.
For most attendees of the show, the insights that I shared into double-blind, placebo-controlled food challenges (DBPCFC) was something new to them. As I discussed, they’re used in trials that involve participants consuming incrementally increasing amounts of a suspect allergen until a mild reaction is detected. This is in addition to them ingesting an indistinguishable non-allergen containing control. I didn’t hold back on pointing out that this approach is the gold-standard for food allergy diagnosis!
Oral food challenges (OFCs) are a novelty for many, so it was no surprise that it triggered the following questions from those watching the presentation:
How is an oral food challenge carried out without a quantitative measure to determine end point?
The challenge is stopped when a predetermined criteria has been met, usually mild symptoms such as headache, nausea etc. There is currently no definitive agreement on the criteria for defining when enough evidence has been established and dosage should be discontinued once a physical reaction occurs, thus ending the challenge. But that’s ok given that the challenge should be carried out by a trained and experienced clinician within a clinical setting.
Objective parameters can be assessed during the trial too. Clinicians may monitor blood pressure and pulmonary functions if considered necessary, particularly if there are any safety concerns based on previous reactions.
Why are OFCs only carried out in allergy clinics or hospitals?
OFC involves oral administration of the suspected allergen in a controlled and standardised setting. It is a complex test, which requires significant healthcare resources. There is a potential risk of the participant having an allergic reaction to the food tested, so OFCs shouldn’t be carried out at home.
An allergy clinician specialist will carefully monitor the participant throughout the trial, checking for any signs of allergic reaction and whether any medical attention is required.
Is the patient at risk and, if so, what benefits does the patient get from being involved in an OFC?
OFC trial participants who experience a mild reaction should view it positively. In the long run, they’re improving their quality of life. It provides certainty that they should avoid certain foods.
For some patients who don’t remember their last allergic reaction, experiencing it during a trial can be an excellent opportunity to see what it feels like and how it is treated.
It is also an opportunity for families to learn how to treat a reaction if their child were to have one. A challenge that ends in a reaction may dispel concerns about severe anaphylaxis and death from even the smallest exposure to a food allergen. It’s great how participation in these trials can greatly improve quality of life and reduce anxiety.
It’s so rare to be at an event with professionals representing so many aspects of healthcare. I like to think that I’ve planted a seed and got people thinking about how we can take a more innovative approach to food allergy diagnosis.