Unintended consequences of infant peanut allergy screening

Published online: January 1, 2021

The landmark Learning Early about Peanut Allergy (LEAP) clinical trial showed that early exposure to peanut can reduce peanut allergy in high-risk infants (defined as a history of egg allergy and/or severe eczema). The trial prompted National Institute of Allergy and Infectious Diseases (NIAID) guidelines in January 2017 recommending screening and early peanut introduction in high-risk infants at around 4 to 6 months of life, food allergy panel testing assessing for multiple foods was discouraged, as allergy tests are known to have poor positive predictive value when assessing foods never previously ingested.

In a recent article in The Journal of Allergy and Clinical Immunology: In Practice, Lo et al. described the results of a retrospective cohort study of 487,533 infants born from 2010 to 2018. Using de-identified administrative health claims, they analyzed the prevalence of infant allergy testing and food allergy diagnoses before and after the LEAP publication in February 2015 and guideline publication in January 2017.

The authors reported an increase in allergy testing in infants overall, including non-high risk infants. Infants getting allergy tested for the first time had multiple allergens tested (post-guideline median number of allergens tested was 9 for serum tests and 10 for skin tests). The median age of post-guideline first-time testing remained over 8 months of age (including in infants ultimately diagnosed with a peanut allergy). Post-guidelines, diagnoses of peanut, egg, and other food allergies (excluding milk) increased significantly.

These findings suggest implementation of guidelines may have had some unintended consequences. Increased testing of infants who are not high-risk may yield false positive results that lead to peanut or other food avoidance in non-allergic infants. Later testing infers that the window for exposure may be missed if families are awaiting testing before peanut introduction. In addition, broad testing for other foods may result in identification of clinically irrelevant sensitization and lead to misdiagnosis of food allergy, if confirmatory oral food challenges are not done.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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