A Look Before You LEAP (into peanut)

What the LEAP Study REALLY means and where do we go from here-insight from allergist, Dr. Dave Stukus, Assistant Professor of Pediatrics in the Section of Allergy/Immunology at Nationwide Children’s Hospita-GUEST POST SERIES.  NOTE: Dr. Stukus is one of my favorites on Twitter with his humor and practical real world advice: @AllergyKidsDoc
From the good doctor:

I was honored to receive an invitation from Caroline (my biggest fan in Nevada) to help her wonderful readers better understand the Learning About Peanut Allergy (LEAP) study. I write this a mere 24 hours after being in the audience for this landmark presentation and still cannot believe all of the energy and buzz surrounding these exciting findings.

Let’s start with why this study was done. Many are familiar that rates of food allergy have been on the rise for the past two decades. Despite many theories, we have not had definitive answers as to why this has occurred. It was previously believed that avoidance was the best way to prevent allergy from developing. But as new evidence emerged, primarily by lead author of the LEAP study, George du Toit, this conventional wisdom was revisited. George du Toit and colleagues observed that children in London had rates of peanut allergy nearly 10 times that of children in Israel. In seeking an explanation, du Toit discovered that the majority of Israeli children consume a peanut derived snack called Bamba, during infancy. Perhaps early introduction could promote tolerance…but there was still a lack of proof.

There has been much confusion and debate about when young children should eat highly allergenic foods. In 2000, the American Academy of Pediatrics recommended no peanuts, tree nuts, or seafood until 3 years of age. Just 8 years later, they released updated guidelines stating that there was insufficient evidence to recommend avoidance of any specific food to prevent the onset of allergic conditions. Needless to say, the confusion regarding these conflicting messages still resonates with pediatricians and parents today.

Thus, the LEAP study was born. The researchers recruited infants 4-11 months of age living in the United Kingdom between 2006-09. All enrolled children had to have eczema and/or egg allergy, both risk factors for the development of peanut allergy. This is a very important point to understand, as results of LEAP may not extend to children who do not meet the same criteria.

The next important point to understand is that people should NOT attempt to reproduce this at home! Every single participant (630 children) in the LEAP study had skin prick tests placed to peanut AND a supervised oral challenge before being given peanut to eat at home. 10% were deemed to risky to proceed based upon size of skin test results and another 13% reacted during challenge. As we move forward, it will be crucial for pediatricians and parents to work with board certified allergists to help select those children with the best odds of success.

Children were divided into those with negative skin tests or mildly positive (1-4 mm size wheal) skin tests to peanut. From there, children were randomized to either eat peanut (roughly 8 peanuts three times a week) or strictly avoid peanut until 5 years of age. Then, at 5 years of age, every child underwent another oral food challenge to peanut (the gold standard for establishing a food allergy diagnosis) to determine if peanut allergy was present.

The LEAP results are astounding. Of those children with negative skin tests, there was an 86% reduced risk of developing peanut allergy between those who ate versus those who avoided peanut. Among children with mildly positive skin tests to peanut, there was a 70% risk reduction between those who ate versus those who avoided. It is important to note that this was not 100% successful and roughly 2% of children with negative skin tests and 11% with mildly positive skin tests still developed peanut allergy despite keeping it in their diet for 4 years.

So where do we go from here? Allergists will need to work together to devise more uniform protocols for evaluating and treating infants at high risk of developing food allergy. We still need more research to see if these results can be duplicated in children from other backgrounds, or with other risk factors, such as infants from other races or ethnicities, or those with milk allergy or with a history of wheezing.  Lastly, all participants were younger than 11 months of age, so it remains unknown whether the same effect could be observed if started after the first birthday. There clearly exists a small window of opportunity to take advantage of immune tolerance mechanisms in the maturing gut of infants.

The LEAP study was not a study about treatment, but demonstrated successful primary and secondary prevention strategies to help pave the way for new ideas and treatment methods. People already living with peanut allergy cannot take these results to help treat or cure their disease, but it may help prevent peanut allergy in their siblings or children. For children at low risk for allergic disease (no parent with allergies, no personal history of eczema or food allergy), there is no evidence to support delayed introduction of peanut or other highly allergic foods into their diet. Many allergists and pediatricians have been trying to relay this since 2008, but adoption has been slow.

We can all rejoice in the wonderful results demonstrated by the LEAP study but must always read past the headlines to learn more. I hope that the information provided here helps answer a few of your questions…I know it will certainly raise many more!

Best wishes to all,

Dave Stukus