Characteristics and Factors Associated with Reaction Severity Among Children Experiencing Reactions During Oral Food Challenges.

INTRODUCTION: Oral food challenges (OFCs) may provoke reactions ranging from mild symptoms to anaphylaxis. Identifying factors associated with severe reactions is important for patient safety. METHODS: We retrospectively evaluated 150 children with IgE-mediated food allergy who experienced reactions during open OFCs for tolerance assessment between October 2022 and March 2026. Clinical and laboratory characteristics were analyzed. Multivariable logistic regression identified factors independently associated with challenge-related anaphylaxis. A sensitivity analysis additionally adjusted for age, sex, total IgE, and reaction step. ROC analysis assessed laboratory markers. RESULTS: Anaphylaxis occurred in 29 (19.3%) patients. In univariate analyses, a history of anaphylaxis at presentation and concomitant allergic diseases were associated with challenge-related anaphylaxis. In multivariable analysis, milk sIgE/total IgE ratio and concomitant allergic diseases remained independently associated with anaphylaxis. Each 1% increase in the ratio increased the odds of anaphylaxis by 5.5% (OR 1.055, 95% CI 1.010-1.103; p=0.013), while concomitant allergic diseases were associated with higher odds (OR 5.75, 95% CI 1.04-31.48; p=0.039). The ratio remained associated with anaphylaxis in sensitivity analysis (OR 1.057, 95% CI 1.010-1.106; p=0.018). ROC analysis showed moderate discrimination for milk sIgE (AUC 0.70), casein sIgE (AUC 0.72), and the ratio (AUC 0.66), with sensitivities of approximately 50%. CONCLUSIONS: Among children who experienced reactions during OFCs, the milk sIgE/total IgE ratio and concomitant allergic diseases were independently associated with challenge-related anaphylaxis. Milk and casein sIgE provided modest discriminatory information with limited sensitivity and should not be considered standalone markers. Larger prospective studies are needed for validation.