The basophil activation test (BAT) is more accurate than standard allergy tests for detecting cow’s milk allergy in children and could reduce the need for oral food challenges in allergy diagnosis.
The study, which was funded by the Medical Research Council (MRC), was led by researchers from:
- King’s College London
- Guy’s and St Thomas’ NHS Foundation Trust
A more accurate assessment of clinical allergy
The BAT 2 milk study looked at the accuracy of BAT in identifying cow’s milk allergy compared to two routinely used allergy tests in 150 children undergoing oral food challenges to cow’s milk:
- skin prick test
- specific Immunoglobulin E (IgE) measurement
The team found that BAT was more accurate at identifying children who reacted to oral food challenges than the skin prick or specific IgE tests, particularly in children under two years old.
The results also showed that the use of BAT as a standalone test could reduce the need for oral food challenges, which are currently used in the clinic to confirm diagnosis.
Transform diagnosis and management
Although BAT is not yet routinely used in clinical practice, the researchers believe that wider adoption of the test could transform the diagnosis and management of cow’s milk allergy.
The test is also about five times cheaper to perform than an oral food challenge.
Alexandra Santos, Professor of Paediatric Allergy at King’s College London, Consultant in Paediatric Allergy at Evelina London Children’s Hospital and senior author of the study, said:
BAT could offer a major advancement in allergy diagnostics, achieving improved diagnostic accuracy and reducing the need (and waiting times) for oral food challenges.
By improving the accuracy of diagnosis, we can ensure children receive appropriate care and avoid the risks and restrictions that come with misdiagnosis, as well as easing the emotional and nutritional burden on families.
Replace existing diagnostic tools
Cow’s milk allergy affects 2% to 3% of babies and young children and is a leading cause of food-induced anaphylaxis.
However, existing diagnostic tools often result in overdiagnosis, leading to unnecessary milk avoidance and related nutritional and developmental concerns.
Allergy tests can also be inconclusive as oral food challenges are often needed to confirm the allergy and whether the food can be safely reintroduced into the diet.
Oral food challenges involve the consumption of small amounts of the allergen under close medical supervision.
Traditional testing methods can lack precision
BAT is a laboratory test that measures how basophils (a type of white blood cell) in a blood sample reacts when exposed to allergens, such as milk proteins.
Unlike traditional testing methods, which can lack precision, BAT offers a more accurate assessment of clinical allergy and could also offer a safer alternative to oral food challenges.
The research, published in the journal ‘Allergy’, represents the largest diagnostic investigation of BAT for cow’s milk allergy to date.
More accurate testing
In the study, children were first offered an oral food challenge with baked milk, and those who tolerated baked milk were offered an oral food challenge with fresh milk.
Among the children tested, 85% were able to tolerate baked milk, while 47% tolerated fresh milk.
Compared to the results of the oral food challenge, BAT was found to be particularly more accurate than the skin prick and specific IgE tests:
- by predicting children who could tolerate baked milk
- at detecting fresh milk allergy, especially in children under two years of age
A positive outcome
For baked milk, out of 100 patients, 88 children were correctly diagnosed with BAT, compared to 69 with specific IgE and 64 with skin prick tests.
Statistical analyses also showed that using BAT would significantly reduce the need for subsequent oral food challenges with baked milk to confirm diagnosis.
Out of 100 children, 49 oral food challenges were required after BAT, compared to 88 after specific IgE and 100 after skin prick tests.
Implementation in routine diagnosis
Introducing baked milk into the diet of children with cow’s milk allergy has been shown to support the development of tolerance and reduce long-term dietary limitations.
The findings suggest that BAT could play a crucial role in guiding safe reintroduction of milk into children’s diets sooner.
BAT could also help to reduce the waiting times and costs associated with oral food challenges.
Professor Santos, said:
I hope that the study will encourage clinical diagnostic laboratories, scientific societies and regulators to support the implementation of BAT in routine diagnosis.