Predictive Value of Molecular Biomarkers for Oral Food Challenge Outcomes in Children with Hazelnut and Peanut Allergies

Background: Food allergy (FA) is an emerging problem in pediatrics, with tree nuts and peanuts being frequent causes of severe reactions. Oral food challenge (OFC) remains the gold standard for diagnosing FA. However, it is a stressful treatment and not always risk-free. Objectives: To identify potential biomarkers, using component-resolved diagnosis (CRD) associated with OFC outcome in children with tree nut (hazelnut, walnut, almond, and pistachio) and peanut allergy, who live in central and southern Italy. Methods: Eighty-eight (1–18 years) children followed at the Pediatric Allergy Clinic of Policlinico Umberto I in Rome were included in this study. All patients underwent skin prick tests (SPTs), prick-by-prick (PbP) tests, and serum-specific Immunoglobulin E (sIgE) measurement to allergenic components using CRDs. Results: In hazelnut allergy (n = 60 OFCs), OFC failure occurred in 41 children. Higher sIgE levels to Cor a 8 (OR 2.04, 95% CI 1.17–3.55), Cor a 9 (OR 2.61, 95% CI 1.37–5.00), and Cor a 14 (OR 1.65, 95% CI 1.14–2.38) were all significantly associated with an increased probability of a positive OFC outcome. In peanut allergy (n = 30 OFCs), OFC failure occurred in 16 children. Ara h 9 was the only statistically significant predictor of OFC failure, showing a very wide confidence interval (OR, 95% CI: 1.116–484). For walnut, almond, and pistachio, sample sizes were insufficient to support inferential modeling. Conclusions: CRD biomarkers can stratify the likelihood of OFC reactions in pediatric FA, enhancing clinical decision-making and reducing unnecessary challenges.