D1.71 - Risk Factors for Anaphylaxis in Food-Allergic Children During Oral Food Challenge Tests

Oral food challenge (OFC) tests are the gold standard for diagnosing food allergies. Despite advancements in diagnostic methods, predicting high-risk cases remains challenging, hence all patients undergo a standard protocol. This study aimed to identify predictive risk factors for positive OFC outcomes, enabling a more personalized approach to patient care.

A retrospective analysis of patients undergoing OFC testing for suspected food allergies at the University Children’s Hospital Ljubljana, Department of Allergology, Rheumatology, and Clinical Immunology between December 2022 and November 2024 was performed. Exclusion criteria included non-compliance or unclear results. Patient history, skin prick tests (SPT), specific IgE to allergen extracts (sIgE) and component resolved diagnostics (CRD) were reviewed, with statistical analyses performed using GraphPad Prism 9.0.

Of 305 OFC tests, 292 were included (66% male, mean age 5.5 years), and 45 (15%) were positive, 8 (17.8%) with Müller grades 3 or 4 reactions. Patient history and diagnostic data is shown in Table 1, and allergen groups in Figure 1.

Risk factors for positive OFC outcomes included a history of any allergic reactions (Müller 1–4; p = 0.0407), with anaphylaxis (Müller 3–4) significant for egg (p = 0.0331). Larger SPT wheal diameters were associated with positive OFCs (p < 0.0001), especially for peanuts, hazelnuts, and walnuts. ROC analysis (AUC 0.76) showed 90% sensitivity for wheal sizes ≤2 mm and 97% specificity for ≥7 mm. Elevated sIgE were a risk factor (p < 0.0001), notably for tree nuts, fish, wheat, and eggs, but not for milk or peanuts. For egg allergy, ROC analysis (AUC 0.84) showed 92% sensitivity and 75% specificity at 6 kU/mL, and >90% specificity at higher thresholds. CRD levels >0.35 kU/L for Ara h 2, Cor a 14, and rTri a 19 were associated with positive outcomes (p = 0.0228), but only 5 (38.5%) of patients with positive CRD had a positive OFC outcome. None of the diagnostic tests predicted OFC reaction severity (Müller 1-2 vs. 3-4).

Patient reaction history, larger SPT wheal sizes and elevated sIgE levels are associated with positive OFC outcomes, though severity cannot be reliably inferred. Positive CRD-specific IgE is not a contraindication for OFC and overall severe reactions are rare (3%). Sample sizes limit conclusions, so the need for larger studies remains.