Test to improve peanut allergy diagnosis

It is hoped the test will be more cost effective and convenient than standard approaches and minimise over-diagnosis of peanut allergy in the community.

Currently, an oral food challenge is the standard for diagnosing peanut allergy, and while an oral food challenge is definitive in diagnosing patients, it is time-consuming, costly and patients risk severe reactions such as anaphylaxis.

The new test researchers have identified uses part of the peanut protein called 'Arah2' and involves a two-step screening process. Researchers found they could perform a blood test, followed by the Arah2 test, which was more accurate and highly predictive than using one of the tests alone. They found the two step testing process reduced the need for oral food challenges by four-fold.

Co-lead researcher, Thanh Dang, a University of Melbourne PhD student based at the Murdoch Childrens Research Institute, said the new test has many benefits.

"By reducing the number of oral food challenges, this helps prevent many peanut allergics undertaking the unnecessary risks involved."

Associate Professor Katie Allen said the new test could reduce the burden on clinicians and the health care system.

"Due to the rapid increase in rates of sensitisation to foods, allergy services are overwhelmed, and food challenge tests might be difficult to access. This method would help alleviate the current strain and demand on clinical allergy services, with the allergy patient waiting times in excess of 18 months in many centres in Australia," she said. Researchers say the test would also help minimise over-diagnosis, and would reduce the number of patients requiring referral to specialist services for confirmation of a food allergy, by using oral food challenges.

Patients would simply need to visit a GP rather than require a referral to a specialist allergy clinic.

"Due to the long wait times for specialist's clinics, many clinicians are faced with the difficult task of having to assess the presence of food allergy based solely on a positive skin prick test or other available tests and must err on the side of caution and accept a diagnosis of 'possible' food allergy in these situations," Dr Allen said

"This approach can lead to over diagnosis of peanut allergy in the community and a potentially unnecessary burden on the health care system," she said.

Diagnosis of peanut allergy is relatively straightforward when there is an obvious history of clinical reaction to peanut ingestion. However, diagnosis can be more complicated in cases in which the clinical history is not clear or in children who have not yet been exposed to a food.

Researchers say the 'Arah2' twostep process can be used in children with high risk of food allergy, such as those with eczema and other food allergies and for those who haven't eaten peanuts but have a strong family history of food allergy.

The study is published in the Journal of Allergy and Clinical Immunology.