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Tuesday, August 11, 2015

Consensus communication on early peanut introduction and the prevention of peanut allergy in high-risk infants

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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