Allergen-specific IgE/total IgE ratio for food allergy diagnosis in children.

Background: This study aimed to assess the relationship of allergen-specific IgE (sIgE) levels and the ratio of sIgE to total IgE (sIgE/tIgE) with the results of the oral food challenge (OFC). Methods: We retrospectively analysed the medical records of children diagnosed with or suspected of having food allergies in the Department of Paediatrics of Peking University Third Hospital between January 2012 and July 2023. Spearman's correlation, receiver operating characteristic (ROC) curves, and logistic regression models were used to compare the sIgE levels, sIgE/tIgE, and OFC results. Results: Eighty-three children with 209 OFC trials were enrolled in this study; sIgE and tIgE levels were tested in 209 children. Among them, 69 children were tested for egg white allergy, 51 for cow's milk allergy, and 52 for wheat allergy. Using multifactorial logistic analysis, in all the samples, the regression coefficient of sIgE was 0.014 (p = 0.1), while that of the sIgE/tIgE was 0.026 (p < 0.01; OR = 1.026). In the egg white allergic group, the regression coefficient of sIgE was 0.032 (p = 0.26), while that of the sIgE/tIgE was 0.02 (p = 0.043; OR = 1.020). No significant differences were observed in the sIgE level or sIgE/tIgE between the cow's milk and wheat allergic groups. Conclusions: The diagnostic value for food allergy sIgE/tIgE ratios, in the total sample and egg white group was better than that of sIgE alone; however, no significant differences were observed in the cow's milk and wheat allergic groups. Further studies with larger sample size or controlled studies are needed to validate these results.