While means of measurement and estimates differ, in the past
ten to fifteen years the prevalence of peanut allergy may have as much as
tripled in countries such as the United States. This translates to nearly
100,000 new cases a year in the United States and United Kingdom. Fleischer et
al. highlight emerging evidence that supports early, rather than delayed,
peanut introduction in the period of complementary food introduction in
infants, including many of those considered to be at high risk for peanut allergy.
(J Allergy Clin Immunol 2015; 136(2): 258-261)
In the Learning Early About Peanut Allergy (LEAP) trial, 640
infants between the ages of four and eleven months, who were considered to be
at high-risk because of egg allergy and/or severe eczema, were randomized to
consume peanut at least 6 grams of peanut protein three times a week or to
completely avoid peanut for the first five years of life. Five hundred and
forty-two of these infants had a negative skin prick test (SPT) response to
peanut at study entry, and ninety-eight of them had a minimally positive SPT
response to peanut (1-4 mm; children with a SPT response to peanut of ≥5 mm were presumed
peanut-allergic and excluded from the trial.)
In an intention-to-treat analysis, 17.2% of the children in
the peanut-avoidance group had food-challenged-proven peanut allergy by the age
of five years; 3.2% of the children in the consumption group did by the same
age. This corresponds to a 14% absolute risk reduction, a number needed to
treat (NNT) of 7.1, and a relative risk reduction of 80%. Overall, the risk of
early peanut introduction in this group was low: 7 of the 319 children
randomized to the consumption group reacted to peanut at the baseline food
challenge, suggesting that peanut food challenges and introduction, even in
children with other risk factors or with minimally positive peanut SPT responses,
are safe and feasible.
Six children in the consumption group developed peanut
allergy during the study, which indicates allergy can still develop despite
primary intervention. In addition, this study focused only on infants
considered to be at high-risk and did not extend to the general infant
population. Still, the study is the first prospective, randomized trial for
early peanut intervention, which its results suggest may reduce the risk of
peanut allergy in this patient population by as much as 80%.
Existing guidelines from 2013, which recommended not
delaying the introduction of any highly allergenic food beyond 4-6 months of
age, did not actively recommend peanut introduction between four and six months
of age in high-risk infants. Based on the data presented above, the authors
suggest the following interim guidelines to aid in clinical decision-making for
early peanut introduction. First, providers should recommend the introduction
of peanut into the diets of high-risk infants between four and eleven months of
age, as an association has been identified between delaying the introduction
and the development of peanut allergy. Second, the evaluation by an allergist
or appropriately-trained physician can assess the appropriateness of peanut introduction
for a given high-risk infant that has severe eczema or egg allergy, and whether
possible allergy testing and observed peanut ingestion would be recommended
first. Finally, the outcomes of the LEAP regimen do not
address the effects of alternative doses of peanut protein, the minimum length
of treatment necessary to induce tolerance, or potential risks of premature
discontinuation or sporadic feeding of peanut. More specific guidelines are
expected later this year from an Expert Panel sponsored by the NIAID.
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