Peanut allergy tolerance treatment may increase the risk of anaphylaxis
Treating children who have a peanut allergy by gradually exposing them to increasing levels of peanut extract may actually increase their risk of allergic attacks, instead of inducing tolerance, warn researchers from McMaster University.
The team found that efforts to desensitize children with peanut oral immunotherapy resulted in three times as many allergic reactions in the “real- world,” compared with peanut avoidance.
Children who tried the desensitization method also had more severe reactions, including potentially fatal anaphylactic reactions that required administration of life-saving adrenaline.
More than six million people are affected by food allergies across Europe and North America, most of whom are children. While children often grow out of the more common egg or milk allergies by the age of ten, a peanut allergy can persist into adulthood and be a lifelong problem.
What is oral immunotherapy?
Previous research has suggested that oral immunotherapy, where allergic children are gradually exposed to increasing levels of peanut extract, can desensitize a child to peanuts, reducing their risk of anaphylaxis.
Researchers say that despite an increased risk of reactions during the initial exposure phase, the ultimate benefits could last a lifetime. Findings from a study last year provided the most convincing evidence to date that the exposure method can stop peanut ingestion triggering a fatal reaction.
However, studies assessing the effectiveness of oral immunotherapy measure the treatment’s success by whether a person can pass a supervised food challenge. Dr. Derek Chu (McMaster University) and colleagues point out that this cannot serve as a predictive measure of a person’s future risk in the real world.
The treatment may not work in the ‘real-world’
Through the analysis of findings from 12 trials, Chu and team questioned whether the results of desensitization studies can be replicated in the real world and have raised concerns about the safety of such approaches. The research was published in The Lancet.
The team pooled data available for more than 1,000 children (aged an average of nine years) who had participated in oral immunotherapy trials and whose progress had been followed for one year.
“Our study synthesizes all randomized clinical trials comparing peanut oral immunotherapy to no immunotherapy in order to generate the highest quality evidence to inform decision-making,” says Chu.
The analysis found that 22.2% of children who underwent oral immunotherapy therapy experienced anaphylactic reactions, compared with 7% who avoided exposure to peanuts.
Serious allergic reactions that led to vomiting, hives, abdominal pain, wheezing and asthma were all increased, including potentially fatal attacks where life-saving adrenaline needed to be given.
The findings favor avoidance of overall current forms of oral immunotherapy and suggest that children who avoid peanuts altogether have fewer attacks overall.
‘More allergic and adverse reactions’
Chu adds that although the exposure method can achieve the aim of desensitization, “this outcome does not translate into achieving the clinical and patient-desired aim of less allergic reactions and anaphylaxis over time.”
Instead, the outcome is the opposite, he says, with “more allergic and adverse reactions with oral immunotherapy compared with avoidance or placebo."
Chu emphasizes that the study does not denounce current research into oral immunotherapy, but that the method should be more carefully considered, with improvements in safety made and measures of success being aligned with patients' wishes.
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