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 (2008–2019), including 7,522 patients aged ≥65 years diagnosed with sepsis. The primary exposure was NLR measured upon intensive care unit (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, each one–standard-deviation increase in NLR (16.29 units) was associated with a 6% higher risk of 28-day mortality (HR: 1.06; 95% CI: 1.03–1.10). When stratified by quartiles, patients in the highest NLR group (>16.0) had a 44% greater mortality risk compared with those in the lowest quartile (HR: 1.44; 95% CI: 1.24–1.68). Survival distributions differed significantly across quartiles (log-rank p < 0.001). However, restricted cubic spline analysis did not demonstrate a statistically significant overall or nonlinear association (P = 0.353 and P = 0.798), and ROC analysis showed modest discrimination (AUC = 0.609; 95% CI: 0.594–0.624). CONCLUSIONS: NLR has a modest association with 28-day mortality in elderly patients with sepsis. Although its predictive value is limited, NLR may serve as an accessible adjunct to established clinical assessments and should be interpreted in conjunction with other clinical indicators.