Scientific Study

Background: The diagnostic value of peanut components is extensively studied in children, but to a lesser extent in adults with suspected peanut allergy. The use of peanut components in daily practice may reduce the need for double-blind placebo-controlled food challenges (DBPCFCs), however validation studies are currently lacking. Objective: To 1) evaluate the diagnostic value of (combined) peanut components and 2) validate a previous found Ara h 2 cutoff level with 100% positive predictive value (PPV) in adults with suspected peanut allergy. Methods: Adults who underwent a peanut DBPCFC were included: 84 patients from a previous study (2002 to 2012) and 70 new patients (2012 to 2019). Specific IgE to peanut extract, Ara h 1, 2, 3, 6 and 8 was measured using ImmunoCAP. Diagnostic value was assessed with an area under the curve (AUC) analysis. Results: In total, 95 (62%) patients were peanut allergic. sIgE to Ara h 2 and Ara h 6 were the best predictors with an AUC (95% CI) of 0.85 (0.79-0.91) and 0.85 (0.79-0.92), respectively. The Ara h 2 cutoff level with 100% PPV (≥1.75 kUA/L) was validated in the 70 new patients. Thirty percent of all included patients could be classified correctly as peanut allergic using this validated cutoff level. Conclusion: sIgE to Ara h 2 and Ara h 6 have equally high discriminative ability. Peanut allergy can be predicted accurately in one-third of adults using a validated cutoff level of sIgE to Ara h 2.