Lymphocyte stimulation test for diagnosing hen’s egg yolk–induced enterocolitis syndrome

There is currently little research into factors predicting the results of an initial diagnostic oral food challenge (OFC) test for food protein-induced enterocolitis syndrome (FPIES). The present study aimed to identify predictors of the diagnosis of hen’s egg yolk-induced FPIES (HEY-FPIES). The present, monocentric study was performed at Tokyo Metropolitan Children’s Medical Center and included patients who underwent hen’s egg yolk OFC (HEY-OFC) between March 2018 and March 2023 to assess for HEY-FPIES. The baseline characteristics of the groups and HEY-OFC positivity or negativity were then compared. Univariate analysis was conducted using the Mann-Whitney U test or Fisher’s exact test. Receiver operator characteristic (ROC) analysis was used to create probability curves. In total, 35 patients were analyzed; of these, 17 were HEY-OFC-positive. No significant difference was observed between the HEY-OFC-positive and negative groups in terms of background factors except the HEY-LST value, which was significantly higher in the HEY-LST group (p = 0.027). ROC analysis demonstrated that the area under the curve for HEY-OFC positivity using the HEY-LST value was 0.719 (95% CI: 0.541-0.897). The statistically optimal cut-off value of HEY-LST was 610%, which had a clinical sensitivity and specificity of 64.7% and 83.3%, respectively. The present study demonstrated that HEY-LST may be a useful predictor of the result of an initial OFC for HEY-FPIES.