Utility of the neutrophil-to-lymphocyte ratio in predicting plasma leakage amongst adults with dengue fever.

Plasma leakage is a hallmark of severe dengue and a major contributor to morbidity and mortality, yet early identification remains difficult, particularly in resource-limited settings. This single-centre retrospective study evaluated the diagnostic accuracy of the neutrophil-to-lymphocyte ratio (NLR) in predicting plasma leakage amongst 507 adults with laboratory-confirmed dengue admitted between January 2022 and December 2023. Plasma leakage was defined sonographically. We assessed NLR trends from illness days 1 to 11 and constructed a bivariate plot of absolute neutrophil and lymphocyte counts to visualise immune dynamics. Ninety-nine patients (19.5%) developed plasma leakage. NLR values differed significantly between groups on days 2-8. Admission NLR showed modest performance (AUROC 0.626), with high sensitivity (87.9%) but low specificity (33.8%). The highest accuracy occurred on day 2 (AUROC 0.923). Whilst NLR alone is insufficient as a diagnostic tool, early phase measurements and visual frameworks of immune cell trajectories may enhance risk stratification for plasma leakage in dengue.