A new study has shown that food challenges may be a safe, effective way to introduce peanut to babies at high risk for peanut allergy, regardless of their skin prick test size. Here’s what families need to know about this new study.
Recent guidelines from the American Academy of Allergy, Asthma, and Immunology (AAAAI) recommend, in order “to prevent peanut… allergy, peanut… should be introduced around 6 months of life, but not before 4 months.”
These guidelines were based on landmark clinical studies, including the Learning Early About Peanut (LEAP) study. The LEAP study’s results have shown that introducing peanuts to babies early and often can help them build up a tolerance to peanut.
But that study excluded a group of infants who had positive skin prick tests to peanut with a reaction size greater than 4 mm. Because their bodies reacted to the peanut in the skin prick test, these infants were shown to be at a high risk of developing (or already having) peanut allergy. So, they were excluded from the LEAP study.
Now, a new study published in the Annals of Allergy, Asthma, and Immunology has shown that food challenges may be a safe and effective way to introduce peanut to these high-risk babies, regardless of their skin prick test size. Here’s what families need to know about this new study.
Skin prick testing and oral food challenges
A skin prick test can help determine if someone is allergic to a certain food. An allergist pricks a person’s skin with a needle that contains a food protein. Then, the allergist examines that area of the skin to see if a wheal (a raised bump surrounded by a red itchy area) appears.
A wheal may be a sign that the person is allergic to that food. But skin prick tests aren’t always accurate— a wheal doesn’t always mean that a food allergy has fully developed.
Learn more about a skin prick test from a child’s perspective, in this video produced by Royal Children’s Hospital in Melbourne, Australia:
Meanwhile, an oral food challenge is the most definitive way to diagnose a peanut allergy.
Usually, during an oral food challenge, someone with a suspected food allergy is fed very small doses of a food in increasing amounts, under allergist supervision. For example, if someone is suspected to have a peanut allergy, an allergist gives them small amounts of peanut. The allergist then watches the person closely to see if they develop an allergic reaction.
In the new study, though, researchers examined oral food challenges as a way to introduce peanut early to babies at high risk for peanut allergies.
The peanut challenge study
The new peanut challenge study aimed to determine if oral food challenges could be used to safely introduce peanut to babies with larger peanut skin prick test results.
National Institute of Allergy and Infectious Diseases (NIAID) guidelines recommend peanut introduction or oral peanut challenges when children have peanut skin prick test (SPT) wheals less than 7mm.
Children with SPT wheals greater than 7mm are likely to be allergic to peanut, says the NIAID, so food challenges generally aren’t recommended for this group. Allergists are often reluctant to give peanut challenges to this group because they’re likely to be allergic.
However, the standard skin prick test size in infants with peanut allergies is unknown. (In other words, we don’t know how large a skin prick test wheal is a reliable sign that a baby has a peanut allergy).
This means that some babies may be told to avoid peanut when they don’t yet have a peanut allergy, and when they would benefit from being introduced to peanut.
So, in the study, the researchers offered peanut challenges to babies with larger skin prick test results, over a two-year period. The challenges involved 1 gram of peanut, a smaller amount than allergists typically use in peanut challenges.
Here’s an overview of the study for families:
|What was the purpose of this study?||To see if babies with large SPT results would tolerate a low-dose peanut challengeTo see if a low-dose peanut challenge is a safe way to start peanut introduction with these babies|
|Who took part in the study, and when?||70 infants between 6-13 months of age who were offered peanut challenges between 12/2015 and 12/201730 had SPT wheals less than or equal to 4 mm40 had SPT wheals greater than 4 mmOf those 40, 22 had SPT wheals greater than 7 mmA substantial number of African American babies took part (significant because African Americans tend to be underrepresented in food allergy research)|
|How was the study conducted?||Infants were offered a food challenge with 1g peanut Parents of babies who tolerated the food challenge were advised to regularly introduce peanut 3 times per weekEvery 4 weeks, these parents were advised to increase the peanut dose by 25%. Eventually this worked up to a goal of 2g peanut 3 times a week if babies tolerated it|
|What did the results show?||97% of infants with SPT wheals less than or equal to 4 mm tolerated the 1 gram of peanut63% of infants with SPT wheals greater than 4 mm tolerated the 1 gram of peanut54.5% of infants with SPT wheals greater than 7 mm tolerated the 1 gram of peanut|
|Were babies who tolerated the peanut challenge able to continue eating peanut regularly at home?||Yes, the majority of babies who tolerated the challenge were. 59% of these babies were eating 2g+ peanut per serving, 3+ times a week.|
The peanut challenge study’s results
Results from the peanut challenge study showed:
- 54 out of 70 babies in the study tolerated the 1 gram of peanut in the food challenge.
- 97% of infants with SPT wheals less than or equal to 4 mm tolerated the 1 gram of peanut.
- 63% of infants with SPT wheals greater than 4 mm tolerated the 1 gram of peanut.
- 54.5% of infants with SPT wheals greater than 7 mm tolerated the 1 gram of peanut
- Although 9 infants who didn’t tolerate the peanut experienced mild or moderate symptoms of an allergic reaction, “There were no severe reactions, transfers to the emergency department, or [hospital] admissions” during the study.
The majority of children who tolerated the 1 gram of peanut were also consuming peanut regularly at 6 to 12 months after the peanut challenge:
- 59% of the 54 babies/toddlers who tolerated the peanut challenge were eating 2 grams or more peanut per serving at least 3 times a week.
- 17% of the 54 babies/toddlers who tolerated the peanut challenge were eating between 1 and 2 grams peanut per serving, at least 3 times a week.
Breaking down the results
The study’s results show that many infants with larger skin prick test wheals tolerate low doses of peanut in an oral food challenge. So, a low-dose (1-gram) peanut challenge can be a safe way to introduce these babies to peanut regardless of their skin prick test size.
The low-dose peanut challenge may also provide a gateway for safe, continued peanut introduction at home, in increasing amounts.
This widens the amount of babies who can safely undergo a supervised, low-dose peanut challenge—and be introduced to peanut early.
As the study’s lead author, Dr. Adora Lin, M.D., Ph.D., FAAAAI, explained to Contemporary Pediatrics: “Current NIAID guidelines for early peanut introduction…do not specifically address management of infants with peanut skin prick tests [greater than] 7 mm. Based on previous studies, these infants are typically advised to avoid peanut. However, in our study, we showed that over 50% of these infants can tolerate a low dose of peanut and can increase the dose at home.”
Continues Lin, “Multiple studies have provided evidence that early introduction of peanut can decrease the incidence of peanut allergy, leading to guidelines from NIAID, the American Academy of Pediatrics, and clinical organizations around the world to recommend early introduction of peanut. However, due to certain risk factors and test results, many physicians may be hesitant to offer introduction of peanut to certain infants… We encourage allergists to consider offering supervised introduction of peanut to infants with large peanut skin prick tests, and present the low—1 gram—dose and home increase in the dose as a strategy that will allow incorporation of peanut into the diet in a developmentally accommodating manner.”
Takeaways for families
What does this mean for families? If your baby has a larger peanut skin prick test result (over 4mm, and even over 7mm), ask your allergist if they would offer a 1-gram peanut challenge to your baby.
If baby tolerates the challenge, they may be ready for regular peanut introduction at home in small amounts (with your allergist’s guidance).
As the study’s authors assert, there are still some risks to this process when a baby has a larger skin prick test, but the benefits are considerable if baby tolerates the peanut.
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