Neutrophil-to-Lymphocyte Ratio (NLR) and Platelet-to-Lymphocyte Ratio (PLR) as Early Predictive Markers of Dengue Severity in Pediatric Patients: A Retrospective Analysis

ABSTRACT Objective: To determine whether neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) within the first three days of dengue illness are independent predictors of dengue severity among pediatric patients. Methodology: A cross-sectional analytical retrospective study was conducted among pediatric dengue patients admitted to The Medical City, Pasig from September 2021 to August 2024. Data collection was done through electronic chart review. Baseline characteristics were analyzed using the Kruskal-Wallis test, Chi-Square test, and Fisher’s exact test. Receiver Operating Characteristic (ROC) and Area Under the Curve (AUC) analyses, along with diagnostic performance metrics, were used to evaluate daily ratio cut-offs differentiating dengue classifications. Multivariable logistic regression was performed to assess NLR and PLR as independent predictors of warning signs or severe dengue development. Results: Among the 316 subjects included in the analysis, 40.5% had dengue fever without warning signs, 57.3% had dengue fever with warning signs, and 2.2% had severe dengue. Differentiating patients without warning signs from those with warning signs, the NLR cut-offs were 4.73, 2.07, and 2.5 on days 1-3, respectively, whereas from those with severe dengue, the cut-offs were 1.27, 0.68, and 0.47 on the same days. For this pairwise analysis, PLR cut-offs were 170, 233.92, and 208.79 for the first comparison; and 209.24, 244.12, and 187.5 for the second, respectively. Statistical analysis showed poor discrimination and diagnostic performance for all cut-offs. Likewise, multivariable linear regression revealed no significant correlation between either ratio and dengue severity. Conclusion: NLR and PLR within the first three days of dengue illness revealed poor performance in predicting the development of warning signs or progression to severe dengue among pediatric patients. KEYWORDS: Dengue fever; Dengue warning signs; Dengue severity; Neutrophil-to-lymphocyte ratio (NLR); Platelet-to-lymphocyte ratio (PLR)