Advances in peanut allergy prevention and treatment

People with severe peanut allergy are at risk of life-threatening anaphylaxis from unintentional ingestion of small amounts of peanuts. A recent new drug review in AFP discussed oral immunotherapy with peanut allergen powder, which increases tolerance for ingesting the amount of peanut protein in a single peanut by 63% but has important downsides: 1 in 10 patients need to use epinephrine after administration (compared to 1 in 20 in a placebo group); common short-term adverse effects include abdominal pain, throat irritation, and oral pruritus; and a price of approximately $3000 annually.

Although it was once believed that children should not consume peanuts early in life, a United Kingdom randomized trial in infants 4 to 11 months of age at high risk of developing peanut allergies (described in this Practice Guidelines summary) found that early consumption of peanuts reduced the risk of developing peanut allergy by age 5 years by 80% (absolute risk reduction=14%, NNT=7). This finding led the National Institute of Allergy and Infectious Diseases to recommend in 2017 that peanut-containing foods be introduced into the diet of infants with severe eczema, egg allergy, or both at 4 to 6 months of age. In 2021, a consensus document on the primary prevention of food allergy from three North American professional allergy societies recommended introducing peanut-containing products to all infants around 6 months of age, regardless of their risk of developing peanut allergy.

A similar change to infant feeding guidelines in Australia occurred in 2016, recommending that all infants be introduced to peanuts before age 12 months. A study in JAMA last week evaluated changes in feeding practices and the prevalence of peanut allergy across two population-based cross-sectional samples recruited in 2007-2011 and 2018-2019. Although infants in the later sample were much more likely to have consumed peanuts before 12 months than infants in the earlier sample (86% vs. 22%), overall there was no statistical difference in peanut allergy prevalence. Noting that East Asian ancestry is considered a risk factor for peanut allergy, the authors hypothesized that the increased representation of infants with parents from East Asia in the later sample may have contributed to finding no effect. Another possible explanation is that early introduction of peanut-containing foods does not significantly modify peanut allergy development in infants not at high risk.

In a previous paper on identifying and using clinical practice guidelines, Dr. David Slawson and I observed: "The ultimate test of a good guideline is whether or not it has been prospectively validated; that is, has its adoption been shown to improve patient-oriented outcomes in real-world settings?" Based on the JAMA study, infant feeding recommendations to prevent peanut allergies have not yet passed this test. On the other hand, an accompanying editorial argued that "given the potential for benefit and the low risk of harm, the [study results] should not dissuade clinicians from following current consensus guidance that recommends early peanut introduction for infants." The challenge of identifying children at increased risk for peanut allergy (as noted in the consensus document, definitions have varied across studies and guidelines) and the inherently artificial nature of previous guidance restricting what an infant would otherwise naturally eat make this a reasonable course of action in the face of imperfect evidence.