Taking a LEAP to prevent peanut allergy

Published Online: June 19, 2015

The prevalence of peanut allergy has increased significantly over the past several decades in many countries, and the cause of this rise is poorly understood. This has challenged investigators to develop strategies to help prevent the onset of peanut and other food allergies. The “Consensus Communication on Early Peanut Introduction and the Prevention of Peanut Allergy in High-Risk Infants,” collectively written by representatives from the American Academy of Asthma, Allergy, and Immunology; American Academy of Pediatrics; American College of Allergy, Asthma and Immunology; Australasian Society of Clinical Immunology and Allergy; Canadian Society of Allergy and Clinical Immunology; European Academy of Allergy and Clinical Immunology; Israel Association of Allergy and Clinical Immunology; Japanese Society for Allergology; Society for Pediatric Dermatology; and World Allergy Organization, highlights emerging evidence from the Learning Early about Peanut Allergy (LEAP) Study supporting early rather than delayed introduction of peanut as a complementary food in infants during the weaning period (transition from formula or breast feeding to solid foods).  

In this consensus document, recently published in The Journal of Allergy and Clinical Immunology (this document will also be co-published in the Journals of several other Allergy/Immunology societies worldwide), 640 infants in the United Kingdom at high risk for peanut allergy, because they had severe eczema and/or egg allergy, were pre-screened before study enrollment with peanut skin testing. They were then classified on the basis of the skin test size (0 mm vs. 1-4 mm) and divided into eating peanut regularly, starting from ages 4-11 months through age 5 years, vs. strict avoidance of peanut until age 5 years. Subjects in each group were then fed peanut under the supervision of physicians to determine which infants had developed peanut allergy. The results showed an 11% - 25% risk reduction of developing peanut allergy, depending on whether they had a positive or negative skin test at study enrollment, supporting early peanut introduction between 4 and 11 months of age rather than peanut avoidance until age 5 years. This translates to an overall number needed to treat (number of patients who need to be treated to prevent one case of peanut allergy) of 7.1 for early introduction in the combined group, irrespective of skin testing. More interestingly, the effect was actually greater within the peanut sensitized (skin test positive) group (NNT=4) than in the skin test negative group (NNT=8.5).

This study is the first prospective, randomized trial of early peanut introduction as an effective intervention to prevent the development of peanut allergy. Given the significance of the results, this consensus document was developed to provide interim advice to healthcare providers regarding the possible benefits of early peanut introduction. Though a policy change is being recommended based on a single study, the effects seen from the study are felt to be so highly beneficial that it may be unethical to repeat the study in other populations, given the potential harm associated with prolonged peanut avoidance. The recommendations in the interim statement highlight that the LEAP Study now provides strong evidence supporting introduction of peanut between 4 – 11 months of age in high-risk infants, adding to existing worldwide guidelines recommending that peanut introduction should not be delayed in infants with significant risk factors for developing food allergy. Though the LEAP Study used specific screening procedures, the consensus document recommends only considering evaluation for possible food allergy in those infants with early-onset allergic diseases, such as severe eczema or egg allergy, before introducing peanut. Such evaluation may include a peanut skin test and/or introduction of peanut for the first time with physician supervision. It also recommends that peanut should not be the first food introduced into an infant’s diet, and that whole peanuts not be given to children younger than age 4 years due to choking risk. A National Institute of Allergy and Infectious Diseases (NIAID)-sponsored Working Group is developing more formal guidelines on complementary feeding of peanut to infants, with more specific recommendations, which will be published within the coming year.

The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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