From Featuring Dr Chris Steele MBE

New peanut allergy test

More accurate than existing tests

Children who have been diagnosed with peanut allergy using skin or blood tests may not be allergic after all, say UK scientists who have developed a new test for the condition.

Peanut allergy is one of the most common food allergies in children, and is one of the "big 8" food allergens.

Eating peanuts can cause a severe allergic reaction known as anaphylaxis which can prove fatal in someone who is susceptible.

Unlike other food allergies, which appear early in life and are usually outgrown by school age (e.g. cow’s milk or eggs), peanut allergy tends to be lifelong.

Past studies have shown that the standard skin and blood tests used to diagnose peanut allergy are unreliable, and may give "false positive" results.

But scientists at the University Hospital South Manchester (UHSM), along with a Swedish firm, have developed a new blood test with a 95% accuracy rate in predicting whether someone will have an allergic reaction to peanuts.

In the study, doctors used standard skin and blood tests for peanut allergy to test 1,000 children aged eight from Manchester.

Although 1 in 10 were found to be positive in the tests, when given biscuits containing peanuts to eat (under carefully controlled conditions), only 1 in 50 were found to have an actual peanut allergy.

Professor Adnan Custovic, who led the study, said: “Avoiding peanuts is the best way of managing allergic/ anaphylactic reactions to peanuts. Complete avoidance is difficult to achieve due to the widespread use of peanuts in prepared foods, and accidental exposures are common and may be life-threatening.

"The fear of possible reaction markedly reduces the quality of life among peanut-allergic patients and their families. However, avoiding peanuts only makes sense if a child is really allergic."

"The new diagnostic test which accurately discriminates peanut allergy from tolerance will mean we can target avoidance to those patients really at risk, and remove the considerable stress that comes from the many false positive sensitivity tests."

The research is published in the January issue of the Journal of Allergy and Clinical Immunology.

This article was published on Mon 11 January 2010