Peanut exposure therapy may lead to three times as many allergic reactions, study says

Allergy researchers argue that desensitisation method could still prevent the most deadly attacks caused by accidental peanut contact

Review comes after trials showed most serious attacks were reduced with exposure therapy (Getty/iStock)

A breakthrough method to prevent life-threatening allergic reactions by exposing suffers to gradually increasing levels of peanut extract may treble attacks, new research suggests.

'Life-changing' findings from a trial last year were the most convincing demonstration yet that this exposure method can prevent accidental ingestion of peanut products triggering a fatal reaction.

But a new analysis of these findings and 11 other trials has questioned whether these results can be replicated outside of laboratory conditions.

Data from more than 1,000 children who had taken part in "oral immunotherapy" trials found 22.2 per cent of children who had exposure therapy experienced anaphylaxis attacks, compared to 7 per cent who practised avoiding accidental peanut exposure.

There were also more serious reactions, which led to vomiting, abdominal pain, mouth itching, hives, wheezing and asthma, as well as attacks where life-saving adrenaline had to be administered.

Their findings suggest that children who did not undergo desensitisation and instead remain focused on avoiding peanuts as an ingredient had fewer attacks overall.

"Numerous studies of varying quality have been published on oral immunotherapy, but its effectiveness and reliability remains unclear,” lead researcher Dr Derek Chu, from McMaster University in Canada said.

The findings, published in the Lancet medical journal, favour an avoidance approach over all forms of oral immunotherapy.

Dr Chu added that exposure goal can achieve the aim of desensitisation “this outcome does not translate into achieving the clinical and patient-desired aim of less allergic reactions and anaphylaxis over time.”

"Instead, the opposite outcome occurs, with more allergic and adverse reactions with oral immunotherapy compared with avoidance or placebo."

More than six million people are affected by food allergies in Europe and North America, including 8 per cent of children and between 2 and 3 per cent of adults, said the scientists.

While common allergies to milk and egg are often outgrown by the age of five to 10, peanut allergy can be a lifelong problem.

Studies of oral immunotherapy measure treatment success by whether a patient can pass a supervised food challenge but not risk in the real world.

However researchers who have led trials in the UK said that their research suggests the most serious attacks might be reduced and despite higher risks during the initial exposure phase the benefits could last a lifetime.

Professor George du Toit, a children’s allergy consultant at Evelina Children's Hospital in London who helped conduct the UK arm of the Palisade trial which reported its findings last November, said: “A safe, simple and symptom-free peanut allergy treatment currently remains elusive.

“We therefore need to determine what degree of risk and discomfort peanut allergic patients are willing to accept and which clinical outcomes are important to patients and their families.”

The Palisade findings were “enough to protect against most accidental exposures, and that the severity of repeat peanut reactions decreased over time,” he added.