For many parents in the typical family physician's practice, recent news about peanut allergy avoidance might just rate a "Mind blown" designation.
According to the American Academy of Allergy, Asthma & Immunology, of the eight foods or food groups that account for nine out of 10 serious allergic reactions in the United States -- milk, eggs, fish, crustacean shellfish, wheat, soy, peanuts and tree nuts -- peanuts are the top culprit among children with a food allergy, followed by milk and shellfish.
In a far cry from the American Academy of Pediatrics' (AAP's) 2000 recommendation to withhold peanuts(pediatrics.aappublications.org) from children considered at risk for developing allergy until age 3 years, newly issued guidelines(www.annallergy.org) call for children at heightened risk for developing peanut allergy (i.e., infants with severe eczema, egg allergy, or both) to start consuming peanut proteins as early as age 4 months to reduce that risk.
Co-published online Jan. 5 in the Annals of Allergy, Asthma & Immunology, the Journal of Allergy and Clinical Immunology, and several other publications, the "Addendum Guidelines for the Prevention of Peanut Allergy in the United States" supplement the "Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the National Institute of Allergy and Infectious Diseases (NIAID)-Sponsored Expert Panel"(www.jacionline.org) released in 2010 and are based in large part on results of the landmark Learning Early About Peanut Allergy (LEAP) trial.(www.nejm.org)
- Representatives from multiple stakeholder groups convened in an NIH-sponsored workshop to develop evidence-based recommendations for the early introduction of dietary peanut to prevent peanut allergy.
- The guideline panel relied heavily on landmark research that examined questions surrounding early introduction of peanut-containing food in children at risk for developing peanut allergy.
- A key takeaway is that infants who have severe eczema, egg allergy, or both are at high risk for developing peanut allergy and should be introduced to small amounts of dietary peanut as early as age 4 months to prevent them from doing so.
Notably, the AAFP played a role in developing and reviewing both the 2010 food allergy guidance and the newly issued recommendations specific to peanut allergy.
A randomized, open-label, controlled trial conducted at a single site in the United Kingdom, LEAP was spurred by an earlier finding that the risk of developing peanut allergy was 10 times higher among Jewish children in the United Kingdom than it was in children of similar ancestry who resided in Israel. This observation correlated with a marked difference in when children in the two countries are introduced to peanuts: U.K. infants typically do not consume peanut-based foods in the first year of life, but Israeli infants are usually introduced to these foods by the time they are 7 months of age.
Given that primary prevention of allergy targets nonsensitized persons, and secondary prevention targets those who are known to be sensitized based on allergen-specific immunoglobulin E (IgE) test results or skin-prick testing reactions, LEAP was designed to determine whether early introduction of dietary peanut was effective as both a primary and a secondary strategy to prevent peanut allergy.
Infants eligible to enroll in the trial were at least 4 months but younger than 11 months of age and had to have severe eczema, egg allergy, or both. A total of 640 study participants were stratified into two cohorts based on the results of a skin-prick test for peanut allergy (no measurable wheal after testing versus a wheal measuring 1 to 4 mm in diameter); participants in each study cohort were then randomly assigned to a group in which dietary peanut would be consumed or a group that would avoid consumption.
Infants assigned to the consumption group underwent a baseline food challenge in which those who had had negative skin-prick results were given 2 g of peanut protein in a single dose and those who had had positive test results were given incremental doses up to a total of 3.9 g.
Participants in the consumption group who had a reaction to the baseline challenge were told to avoid peanuts and were included in the intention-to-treat analysis but not in the per-protocol analysis. Those who did not have a reaction were fed at least 6 g of peanut protein per week until they reached age 60 months.
All infants were clinically assessed using skin-prick testing and serum IgE and other immune marker measurements at various points during the study. The primary outcome was the proportion of participants with peanut allergy at 60 months and was determined via an oral food challenge.
In all, 530 of the 542 children with a negative result on the initial skin-prick test were evaluated for the primary outcome and were included in the intention-to-treat analysis. Of these, 13.7 percent of the avoidance group and 1.9 percent of the consumption group were allergic to peanuts at 60 months; this absolute difference in risk of 11.8 percentage points represents an 86.1 percent relative reduction in peanut allergy prevalence.
Of the 98 children who had positive results on the initial skin-prick test and were evaluated for the primary outcome, 35.3 percent of the avoidance group and 10.6 percent of the consumption group were allergic to peanuts at 60 months; the absolute difference of 24.7 percentage points represents a 70.0 percent relative reduction in the prevalence of peanut allergy.
The per-protocol analysis included 500 of the 530 infants with negative results on the initial skin-prick test and 89 of the 98 infants with positive results on the test. For each group, results in the per-protocol population were similar to those observed in the intention-to-treat population.
Armed with these findings and other emerging data, representatives from multiple stakeholder groups convened in a workshop sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) to
- "develop evidence-based recommendations for the early introduction of dietary peanut to prevent peanut allergy;
- agree on principles for grading the evidence;
- achieve consensus while allowing ample opportunity for consideration of divergent opinions;
- determine whether the recommendations could extend beyond peanut to other food allergens; and
- keep patient and societal interests at the forefront."
The resulting guidance consists of three specific guideline statements segmented by infants' level of risk for developing peanut allergy. A brief description of each guideline recommendation developed by the NIAID-convened expert panel and vetted by a coordinating committee that included numerous medical professional representatives, including Academy member Jason Matuszak, M.D., of Buffalo, N.Y., follows.
Infants with severe eczema, egg allergy, or both are at high risk for peanut allergy and should be introduced to age-appropriate peanut-containing food as early as age 4 to 6 months to reduce that risk. It's important to ensure that other solid foods have been introduced first to confirm that the infant is developmentally ready. The guideline also recommends that peanut-specific IgE measurement, skin-prick tests, or both be strongly considered before peanut is introduced to determine whether introduction is appropriate and, if so, the preferred method of introduction.
To minimize the chance that introduction is delayed for infants who may test negative, peanut-specific IgE measurement may be preferred in certain health care settings -- including family medicine practices -- where skin-prick testing is not commonly performed. Alternately, clinicians may choose to refer for subspecialty assessment.
Introduction method recommendations depend on the results of each type of testing. A peanut-specific IgE level of less than 0.35 kUA per L (kilo units of allergen-specific IgE per liter) is considered to be a strong negative predictor for a diagnosis of peanut allergy. Such a finding should prompt introduction of dietary peanut soon thereafter, with a cumulative dose of about 2 g of peanut protein given in the initial feeding. This can be done at home or in a supervised feeding in the clinician's office. A level of 0.35 kUA per L or more warrants referral for further consultation and possible skin-prick testing.
An infant in whom a skin-prick test for peanut allergy produces a wheal of 2 mm or smaller compared with saline control should also be introduced to dietary peanut shortly thereafter, with the same cumulative first dose of about 2 g of peanut protein in a single feeding. Referral is indicated for infants in whom skin-prick testing produces a wheal 3 mm in diameter or larger than that elicited by saline control.
Infants with mild-to-moderate eczema should be introduced to age-appropriate peanut-containing food at about age 6 months and according to family preferences and cultural practices. The same caveat about introducing other solid foods first also applies to these children. Overall, children in this category need not present for an in-office evaluation before peanut is introduced at home, but the guideline's authors recognize that some caregivers may prefer an in-office supervised feeding, or evaluation, or both.
Notably, this particular recommendation is based largely on expert opinion and extrapolation of data from a single study; the LEAP study did not focus on this patient population.
Finally, infants without eczema or any food allergy should have age-appropriate peanut-containing foods freely introduced in the diet together with other solid foods in keeping with family preferences and cultural practices.
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