Validation of the Neutrophil-Lymphocyte Ratio as a Mortality Risk Stratification Marker in Patients with Proximal...

Background/Objectives: Proximal femoral fractures (PFF) are associated with substantial morbidity and mortality in elderly patients. Early identification of individuals at increased risk of death remains challenging. The neutrophil-to-lymphocyte ratio (NLR) is an inexpensive and readily available biomarker reflecting systemic inflammation and physiological stress, but its role as a risk stratification tool in surgically treated PFF patients is not fully established. The aim of this study was to validate NLR as a prognostic biomarker for mortality risk stratification in elderly hip fracture patients by evaluating its independent association with mortality, establishing clinically relevant risk categories, and assessing its ability to identify distinct mortality risk groups. Methods: This retrospective cohort study included 1113 patients aged ≥ 65 years who underwent surgery for AO/OTA 31.A (trochanteric) or 31.B (femoral neck) proximal femoral fractures between January 2021 and February 2024 at a single institution. NLR was calculated from routine admission bloodwork. The primary outcome was all-cause mortality. Kaplan-Meier survival analysis stratified patients by clinically relevant NLR categories (<5, 5-10, >10). Cox proportional hazards regression identified independent predictors of mortality. ROC analysis was performed secondarily to identify an optimal binary threshold. Results: At mean follow-up of 33.9 months, overall mortality was 36.2% (352/972). Stratified survival analysis demonstrated a clear dose-response relationship, with mortality rates of 26.2%, 36.5%, and 54.4% for NLR < 5, 5-10, and >10, respectively (log-rank p < 0.001). In multivariable Cox regression, NLR remained independently associated with mortality (HR = 1.042, 95% CI: 1.032-1.053, p < 0.001) after adjusting for age and time to surgery. ROC analysis identified an optimal binary cut-off of 6.59 (AUC 0.614). Conclusions: Elevated preoperative NLR is independently associated with increased mortality following surgery for proximal femoral fractures, particularly in very elderly patients. Given its simplicity and universal availability, NLR may represent a useful adjunct for early perioperative risk stratification.