Evaluating High Fluorescence Lymphocyte Count as a Predictor of Severe Dengue Infection

Dengue infection (DI) is a significant global health concern, with severe cases leading to plasma leakage, organ failure, and shock. Identifying reliable biomarkers for early risk stratification is crucial for improving patient management.

This descriptive cross-sectional study included 268 DI patients at 103 Military Hospital, Vietnam, from July 2022 to October 2023. Patients were classified into Non-Severe DI and Severe DI groups per the 2009 WHO dengue guideline. High Fluorescent Lymphocyte Count (HFLC), a parameter from the Sysmex hematology analyzer, was analyzed. HFLC% represents the proportion of high fluorescent lymphocytes among total WBCs, while HFLC# is these cells' absolute count (G/L). Statistical methods included Mann-Whitney U, Kruskal-Wallis, Chi-square tests, ROC curve analysis, and binary logistic regression.

HFLC% and HFLC# were significantly elevated in Severe DI compared to Non-Severe DI (p < 0.001). HFLC% negatively correlated with platelet count and positively with liver enzymes (AST, ALT), suggesting an association with severe complications. ROC analysis showed that HFLC# (AUC = 0.913, p < 0.001, cut-off = 1.00 G/L) had 70.6% sensitivity and 90.8% specificity, while HFLC% (AUC = 0.833, p < 0.001, cut-off = 13.15%) had 70.6% sensitivity and 80.5% specificity for predicting severe DI.

Elevated HFLC at admission is strongly associated with severe DI, with HFLC# demonstrating excellent predictive accuracy. These findings suggest that HFLC is a promising biomarker for early identification of high-risk dengue patients. Further large-scale validation is required to confirm its clinical utility.