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A number of peanut allergy screening tests exist. Which is the best for infants who are high risk?
For many infants, introduction of peanuts can be done with very little risk and can help reduce the risk of developing a peanut allergy. However, it’s now recommended that high-risk infants are screened for peanut allergy before introducing the food. An investigation in the Journal of Allergy and Clinical Immunology offers information on whether one screening approach was better than the others.1
The investigators looked at infants aged 4 to 11 months that had no history of peanut ingestion, testing, or reaction as well as moderate-severe eczema; history of food allergy; and/or first-degree relative with a history of peanut allergy. Each infant was given a peanut skin prick test, peanut specific immunoglobulin E (IgE) testing, and component immunoglobulin E testing. Depending on the size of wheal from the peanut skin prick test, the infant might also undergo an oral food challenge or have observed feeding.
A total of 321 infants were included in the study and 37 of the infants were found to have a peanut allergy. The researchers found that Ara h 2-specific IgE at a cutoff point of kUa/L was the best at discriminating between allergic and nonallergic (area under the curve [AUC], 0.96; sensitivity, 94%; specificity, 98%), when compared to with peanut-specific IgE at 0.1 kUa/L (AUC, 0.89; sensitivity, 100%; specificity, 78%) or 0.35 kUa/L (AUC, 0.91; sensitivity, 97%; specificity, 86%), or a skin prick test with a wheal size of 3 mm (AUC, 0.90; sensitivity, 92%; specificity, 88%) or a wheal size of 8 mm (AUC, 0.87; sensitivity, 73%; specificity, 99%). When included in a mode with Ara h 2-specific IgE, both Ara h 1-specific IgE and Ara h 3-specific IgE could not add to predicting peanut allergy. Additionally, Ara h 8-specific IgE was found to discriminate poorly (AUC, 0.51).
The investigators concluded that using only Ara h 2-specific IgE should be thought of when screening high-risk infants who have not yet been introduced to peanuts.
1. Keet C, Plesa M, Szelag D, et al. Ara h 2–specific IgE is superior to whole peanut extract–based serology or skin prick test for diagnosis of peanut allergy in infancy. Journal of Allergy and Clinical Immunology. January 19, 2021. Epub ahead of print. doi:10.1016/j.jaci.2020.11.034