The Complexities of Early Peanut Introduction for the Practicing Allergist.

Recommendations for the timing of introducing major food allergens, such as peanut, into the diet of at-risk infants have undergone major changes in the past decade. The most substantial modification has been a shift toward advice that delaying beyond 4 to 6 months does not prevent and might actually increase the risk of food allergy. The Learning Early About Peanut (LEAP) study published last year provided strong evidence that early peanut introduction with regular ingestion has a potentially dramatic benefit. Although there is little current doubt of the effectiveness of early peanut introduction, many unanswered questions remain. Previous guidelines defined infants at risk as those with a first-degree relative with allergic disease, whereas the LEAP study defined high risk as severe eczema or egg allergy. The LEAP study chose to screen infants but did not have a comparison group randomized without screening. In the following case-based discussion, we explore the complexities of LEAP implementation for the practicing allergist. These include nonuniformity in the literature for defining at-risk infants, difficulties in assessing eczema severity objectively, variable adherence to current guidelines, proposed peanut screening methods contrasting with existing food allergy guidelines to not routinely screen before ingestion, unclear interpretation of positive test results if screened, risks of screening extending to foods not studied in the LEAP study, and uncertainties about the optimal dose and duration of peanut once introduced.