New test that can more accurately diagnose peanut allergy

A more convenient and cost-effective way of testing children for peanut allergy has been developed by the Murdoch Children’s Research Institute in Melbourne, Australia. At the moment the use of oral food challenge (OFC) in detecting peanut allergy is the most conclusive test, but this method is risky due to the possibility of anaphylaxis, as well as costly and time-consuming.

Due to the long wait for a specialist clinic, clinicians are assessing the presence of a food allergy using only a skin prick test, and must always err on the side of caution. The waiting list for allergy testing is 18 months in some places in Australia and the new test would cut waiting lists as well as minimise over-diagnosis, whereby some people are told to cut out more foods from their diets than they really need to, and thus reduce the numbers of patients referred to specialist services.

The new test involves a two-fold process. Firstly a blood test which could be carried out at the GP clinic. Then, the researchers have found that they can use part of the peanut protein called Ara h 2, to determine sensitivity to peanut, which is more accurate and highly predictive than using one of the tests alone. This test can also be used for high-risk children who come from a family with a history of atopy, but who have not eaten peanuts.

The study carried out by the researchers involved infants from the HealthNuts study who were skin prick tested to determine sensitisation, and then underwent an OFC to confirm allergy status. In a random sample of 200 infants, where 100 had peanut allergy and 100 were peanut tolerant, it was found that testing for the protein Ara h 2 was more accurately predictive of peanut allergy than testing for the whole peanut protein.

Source: Journal of Allergy and Clinical Immunology

First published in March 2012

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