Prognostic value of hematological ratios in sepsis: A prospective observational study of neutrophil-to-lymphocyte, platelet-to-lymphocyte, and monocyte-to-lymphocyte ratios

Background: Early identification of high-risk sepsis patients remains a clinical priority. Hematological ratios such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) have emerged as potential prognostic biomarkers reflecting systemic inflammation and immune dysregulation in sepsis. To evaluate the prognostic significance of NLR, PLR, and MLR in predicting clinical outcomes in patients with sepsis, including mortality, hospital stay duration, and need for mechanical ventilation. Methods: This prospective cross-sectional observational study included 200 adult patients (>18 years) with clinically diagnosed sepsis admitted to a tertiary care hospital from January 2023 to March 2025. Complete blood counts were used to calculate NLR, PLR, and MLR. The Sequential Organ Failure Assessment score was used to assess organ dysfunction. Statistical comparisons were performed using t -tests, ANOVA, Chi-square tests, and receiver operating characteristic (ROC) curve analysis. Correlation analyses were also conducted. Results: Higher NLR and MLR values were significantly associated with prolonged hospital stay ( P = 0.0031 and P = 0.0027, respectively) and need for mechanical ventilation ( P = 0.0018 and P = 0.0012, respectively). ROC analysis revealed that NLR (area under the curve [AUC] =0.797) and PLR (AUC = 0.707) had good predictive accuracy for mortality. No significant difference was observed in inflammatory ratios between death and discharge groups. Conclusion: NLR and MLR serve as reliable prognostic indicators in sepsis and correlate significantly with disease severity and outcomes. Their inclusion in the initial sepsis workup may support early risk stratification and clinical decision-making.