Published online: January 19, 2021
Clinical trials have shown that early introduction of peanut during infancy can prevent peanut allergy. While most countries, public health authorities, and professional societies now recommend “early” introduction of peanut, there are many areas of controversy about how to implement this recommendation in practice. One of those controversies is whether to screen any subgroup of infants prior to the introduction of peanut in infancy. In the U.S., guidelines from a National Institute of Health-sponsored expert panel recommend that providers strongly consider screening infants with severe eczema or egg allergy prior to the introduction of peanut at around 4-6 months. Guidelines in many countries in Europe and Australasia, however, do not recommend screening prior to peanut introduction. Furthermore, while current guidelines do not recommend screening siblings or children of peanut allergic patients prior to introduction, this is commonly done in practice.
In a recent article in The Journal of Allergy and Clinical Immunology (JACI), Keet et al. report the results of a prospective study of infants at risk of peanut allergy. They enrolled 325 infants ranging from 4 to 11 months of age at Johns Hopkins School of Medicine and Massachusetts General Hospital for Children. Inclusion criteria included moderate to severe eczema, a non-peanut food allergy, or an immediate family member with peanut allergy, but who had not previously introduced peanut or had testing for peanut allergy. Infants were given a peanut skin prick test and blood was drawn for peanut-specific IgE and IgE antibodies to Ara h 1, Ara h 2, Ara h 3 and Ara h 8 peanut components. Depending on the results of the peanut skin prick test, an oral food challenge or observed feeding of peanut was performed. After the first 9 participants with peanut skin prick wheals larger than 10 mm failed their oral food challenge, remaining participants with peanut skin prick test larger than 10 mm were deemed peanut allergic without further peanut exposure.
Keet and colleagues reported that peanut allergy was common among infants with eczema, as 18% of infants with eczema already had peanut allergy at the time of screening. Among those with eczema, increased age and increased severity of eczema both increased the risk of peanut allergy, with each additional month of age conferring a 30% increased odds of peanut allergy. Moreover, every 5-point increase in the objective Scoring Atopic Dermatitis (SCORAD) increased the odds of allergy by approximately 20%. In contrast, a family history of peanut allergy did not substantially increase risk, as only 1% of infants who had a sibling or parent with peanut allergy but who did not have eczema were peanut allergic.
Overall, these findings support guidelines recommending that peanut be introduced as soon as possible among high-risk infants in order to prevent peanut allergy. The high rate of peanut allergy among children with severe eczema, particularly later in the first year of life, suggests that screening prior to peanut introduction may be considered in a select group of infants. In contrast, families and providers can be reassured that a family history of peanut allergy alone is not a large risk for peanut allergy, and thus it should not be an indication to screen. Guidelines for peanut introduction may need to be “fine-tuned” to reflect these findings.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.