Predictive Value of the Neutrophil-to-Lymphocyte Ratio for 28-Day Mortality in Elderly Patients with Sepsis: A Cohort Study Based on the MIMIC-IV Database

BACKGROUND: The prognostic value of the neutrophil-to-lymphocyte ratio (NLR) in elderly patients with sepsis remains uncertain. This retrospective cohort study investigated the association between NLR at hospital admission and 28-day mortality in this population. METHODS Data were extracted from the MIMIC-IV database (2009–2019), including 7,522 patients aged ≥65 years diagnosed with sepsis. The primary exposure was NLR measured upon ICU admission, and the outcome was 28-day all-cause mortality. Multivariable Cox proportional hazards models and Kaplan–Meier survival analyses were employed to assess the relationship between NLR and mortality risk. Sensitivity analyses were performed to validate the robustness of the results. RESULTS Among the 7,522 patients analyzed, a one standard deviation rise in the neutrophil-to-lymphocyte ratio (NLR), equivalent to 16.29, corresponded to a 6% elevation in the risk of 28-day mortality (hazard ratio [HR]: 1.06; 95% confidence interval [CI]: 1.01–1.10). When stratified by quartiles, individuals in the highest NLR group (>16.0) had a 47% greater mortality risk compared to those in the lowest quartile (HR: 1.47; 95% CI: 1.23–1.75). Survival distributions across the NLR quartiles, assessed using Kaplan–Meier curves, revealed statistically significant disparities (log-rank test, p < 0.001). CONCLUSIONS: In this extensive cohort of older adults diagnosed with sepsis, elevated neutrophil-to-lymphocyte ratio (NLR) levels at the time of ICU admission were independently linked to a higher risk of death within 28 days. These results indicate that NLR could function as a practical and accessible prognostic tool for assessing mortality risk in this high-risk patient group.