Monocyte-to-Lymphocyte Ratio Predicts Mortality After Vascular Surgery - A Prospective Cohort Study

Abstract

Objectives: This study aims to evaluate the association between preoperative monocyte-to-lymphocyte ratio (MLR) and 30-day postoperative mortality (POM), major adverse cardiac events (MACE) and acute kidney injury (AKI) in patients undergoing vascular surgery. Methods: A prospective observational cohort study was conducted at a tertiary university hospital, including all adult patients who underwent elective vascular surgery between January 1 and April 30, 2015. Preoperative demographic, clinical and laboratory data, including complete blood counts, were collected and MLR was calculated by dividing the absolute monocyte count by the absolute lymphocyte count. The primary outcome was 30-day POM, while secondary outcomes included MACE and renal complications. The optimal MLR cutoff value was determined using receiver operating characteristic (ROC) curve analysis. Independent predictors of POM were identified using multivariate logistic and Cox regression analyses. Results: A total of 216 patients were included in the final analysis. The optimal MLR cutoff of 0.39 demonstrated a sensitivity of 0.72 and specificity of 0.52. The overall 30-day POM rate was 6.5% (14 patients). Patients with MLR ≥ 0.39 had a significantly higher mortality rate (8.7% vs. 4.5%, p = 0.028) and an increased incidence of MACE and AKI compared to those with MLR < 0.39. Multivariate analysis identified MLR (OR = 3.45, 95% CI: 1.14-10.4, p =0.028) and age (OR = 1.07, 95% CI: 1.02-1.13, p = 0.009) as independent predictors of POM. Cox regression analysis confirmed these findings, with MLR associated with a 2.74-fold increased risk of mortality (HR = 2.74, 95% CI: 1.06-7.10, p = 0.038). The predictive model combining MLR and age demonstrated superior discrimination for POM (AUC = 0.744) compared to either factor alone. Conclusions: Preoperative MLR is an independent predictor of POM in patients undergoing elective vascular surgery. Elevated MLR values are associated with increased mortality, MACE and AKI, highlighting their potential role in risk stratification. Given its availability and cost-effectiveness, MLR could enhance existing risk stratification models, facilitating improved perioperative management. Further large-scale, multicenter studies are needed to validate these findings and explore the integration of MLR into clinical decision-making frameworks.