Study Says Many Infant Peanut Allergy Diagnoses May Be Incorrect

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Five-month-old Arthur’s face turned red the first time he ate peanut, and hives appeared on his shoulders and upper lip.

“Our GP referred us to an allergy specialist who took skin prick and blood tests,” Arthur’s mom Leah said in a news release. “The results suggested Arthur had a high risk of reacting to peanut, and we were advised to avoid it while we awaited further tests.”

But when Arthur later had a follow-up food challenge at age 1, he was given peanut under medical supervision to see whether he truly had an allergy — and he had no reaction. The peanut allergy label was removed.

Arthur’s experience is not unusual, according to a new study.

Researchers reported in The Journal of Allergy and Clinical Immunology: In Practice that more than one-third of infants believed to have peanut allergy may actually have been misdiagnosed.

The study found that about 35% of infants who had a recent reaction to peanut and a positive allergy test later had their diagnosis reversed.

Those diagnoses were overturned after the children did not react when peanut was given to them during a doctor-supervised challenge, the researchers said.

“We found more than one third of infants who were suspected to have peanut allergy based on their history and initial tests no longer reacted when they underwent a supervised food challenge,” said lead author Dr. Timothy Brettig, a senior research clinician at Murdoch Children’s Research Institute in Australia.

“Being able to identify those children early allows them to avoid an unnecessary allergy label and the burden of avoiding peanut,” Brettig said in a news release.

The findings came from an Australian study looking at whether peanut allergies can be treated by exposing allergic babies to small amounts of peanut.

In the study, 1,275 infants younger than 18 months were evaluated, and 778 underwent an oral food challenge to confirm whether they had peanut allergy.

In a food challenge, infants are given gradually larger amounts of peanut under medical supervision to see whether they have an allergic response, researchers explained in background notes.

About 65% of the babies who took part in the oral food challenge did have an allergic reaction, including 12% who had a severe reaction, the results showed. Medical staff safely managed all of those episodes.

The remaining 35% of children, although believed to be allergic to peanut, had no reaction and could have the allergy label removed, the researchers said. Those infants could then eat peanut regularly in an age-appropriate form, which may help strengthen their protection against allergy.

Arthur was among the children in the study who were found not to actually have a peanut allergy, despite earlier signs that seemed to point that way.

“We were understandably anxious going into the challenge, because we didn’t know how Arthur would respond,” Leah said. “It’s a huge relief knowing Arthur can tolerate peanut, and we can move forward without the uncertainty of managing a suspected allergy. Having the opportunity to find out he could tolerate peanuts has made a real difference to our family.”

The results suggest doctors should do more testing before deciding an infant has peanut allergy, the researchers concluded.

“Oral food challenges are not currently used routinely for every infant with suspected peanut allergy,” researcher Kirsten Perrett, group leader of population allergy research at Murdoch Children’s Research Institute, said in a news release. “But our results show that clinical history and allergy testing alone were not enough to accurately diagnose peanut allergy in many cases.”

“A supervised oral food challenge should be routinely considered to confirm the diagnosis before an infant starts oral immunotherapy,” she added. “With peanut allergy one of the most common childhood food allergies, it’s particularly important that we have an accurate diagnosis when a baby first shows signs of a possible peanut allergy.”

Nearly all of the babies who reacted during the food challenge went on to oral immunotherapy, a treatment in which they are given daily doses of peanut to help build tolerance, the researchers said.

The researchers advised parents to ask about an oral food challenge to confirm a peanut allergy diagnosis based on medical history and allergy testing.

“We strongly recommend considering this approach for diagnosing peanut allergy in infants regardless of whether oral immunotherapy or an allergen avoidance strategy is pursued,” the paper concluded.

SOURCES: Murdoch Children’s Research Institute, news release; The Journal of Allergy and Clinical Immunology: In Practice

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