Real-life Infant Peanut Allergy Testing in the Post-NIAID Peanut Guideline World

To characterize the use of peanut allergy screening at a single center in infants with severe eczema and/or egg allergy and those not meeting high-risk National Institute of Allergy and Infectious Diseases (NIAID) screening criteria.

This study included 112 infants (under the age of 12 months) who were tested for peanut sensitization. Of those tested, 84 infants were screened prior to first peanut introduction, and 28 were tested to evaluate a prior reaction upon peanut ingestion/exposure.

A retrospective chart review was performed.

Among the 84 infants who were screened prior to introduction, only 48% met NIAID screening criteria. Of all infants screened prior to introduction, 52 had a negative peanut skin prick test (defined as wheal of 0–2 mm), and 2 infants had peanut-specific IgE levels less than 0.35 kU/L. Home peanut introduction was successful in 92.6% of infants with negative tests. Sixteen infants (19%) had peanut skin prick test wheal of 3–7 mm; however, only 50% were offered OFC (57% pass rate of those with known outcomes, no severe reactions). Nine infants (11%) had a peanut skin prick test wheal greater than 7 mm and all were presumptively diagnosed with peanut allergy (none were offered OFC). Of the 28 patients tested due to prior reactions, 14% received epinephrine as part of reaction treatment, but only 21% would have met NIAID screening criteria. Of those who would have met NIAID screening criteria, none had a severe index reaction.

In this review, over half of infants who were screened for peanut allergy did not meet NIAID criteria for screening. In addition, half of infants with skin test wheal sizes of 3–7 mm did not receive supervised oral food challenges to confirm or refute peanut allergy. Negative skin testing did not guarantee tolerance, and positive skin testing did not clearly predict allergy. Most children who experienced clinical peanut reactions did not fulfill NIAID screening criteria.

Despite NIAID recommendations for pre-ingestion peanut screening for infants with severe eczema and/or egg allergy, the practice is not cost-effective and results in more cases of peanut allergy than it prevents. The US remains the only nation continuing to routinely recommend this screening practice for high risk infants. This study demonstrates the phenomenon of “screening creep” is a real-life consequence of well-intended (but not validated) recommendations. Unfortunately, the distinction between mild, moderate, and severe eczema is imprecise. At a minimum, the decision for pre-emptive allergen screening prior to ingestion must be made in a shared-decision making context which is evidence-based and patient-informed. Unless caregivers have a high preference to avoid an index reaction to peanut (or experience a first reaction under supervision), risk for peanut allergy overdiagnosis likely overshadows benefit of early screening when compared with careful gradual home first introduction of peanut allergen.