Clinical and immunological predictors of baked egg tolerance in children with IgE-mediated hen's egg allergy: a cross-sectional diagnostic accuracy study.

Baked egg (BE) introduction in IgE-mediated hen's egg allergy (HEA) is a practical strategy for dietary diversification and may promote future tolerance to hen's egg. This study aims to characterise clinical and immunological profile of children with HEA undergoing BE oral food challenge (BE-OFC) and to evaluate the individual and combined predictive performance of serum-specific IgE (sIgE), skin prick test (SPT), and basophil activation test (BAT) for BE tolerance. This is a cross-sectional diagnostic accuracy study of children aged 12 months to less than 6 years with confirmed IgE-mediated HEA attending a tertiary referral centre in Barcelona. All participants underwent standardised open BE-OFC. Receiver operating characteristic (ROC) analysis was used to evaluate biomarker performance. Exploratory associations with BE tolerance were examined using Firth's penalised logistic regression. Fifty-one children completed BE-OFC; 56.9% were tolerant. Tolerance was lower in those with prior anaphylaxis (35.7% vs 64.9%), without statistical significance (p = 0.111). During BE-OFC, epinephrine was required in only two of 22 non-tolerant patients. Ovomucoid (OVM)-sIgE was the best-performing single biomarker (AUC 0.71; 95% CI 0.55-0.87; cutoff 4.48 kUA/L; sensitivity 68.2%; specificity 79.3%). Tolerant patients demonstrated lower BAT net stimulation responses across egg white concentrations. Neither SPT nor BAT markers achieved meaningful discrimination. In adjusted analyses, OVM-sIgE retained a significant independent association with BE tolerance (OR 6.2; 95% CI 1.9-22.8), while the effect of age was attenuated to non-significance. Conclusion: OVM-sIgE was the strongest predictor of BE tolerance in young children with IgE-mediated HEA. Supervised OFC appears safe even in children with prior anaphylaxis. Findings are exploratory and require prospective multicentre validation.