Preoperative Lymphocyte-To-Monocyte Ratio as a Prognostic Predictor of Long-term Mortality Among Cardiac Surgery Patients: A Propensity Score Matching Analysis Based on a 4-year Follow-up Cohort

Abstract BackgroundCardiac surgery is associated with a specific inflammatory response. The lymphocyte-to-monocyte ratio (LMR) has been shown to be related to the prognosis of many cardiovascular diseases. We aimed to evaluate the prognostic value of the preoperative LMR in patients who underwent cardiac surgery.MethodsClinical data were extracted from the Multiparameter Intelligent Monitoring in Intensive Care (MIMIC)-III database. The optimum cutoff value of the LMR for 4-year mortality was determined by X-tile software. The Cox proportional hazard model was applied for the identification of independent prognostic factors of 4-year mortality. Survival curves were estimated using the Kaplan-Meier method, and receiver operating characteristic (ROC) curves were constructed. The 1:1 propensity score matching (PSM) method was performed to balance the influence of selection bias and potential confounding factors.ResultsA total of 1701 patients were included. The X‐tile software indicated that the optimum cutoff value of the LMR for 4-year mortality was 3.58. After PSM, 489 pairs of score-matched patients were generated. The Cox proportional hazard model showed that patients with an LMR < 3.58 had a significantly higher 4-year mortality than patients with an LMR ≥ 3.58 in the entire cohort (HR = 1.925, 95%CI: 1.509-2.456, p < 0.001) and the PSM subset (HR = 1.568, 95%CI: 1.2-2.05, p = 0.001). The Kaplan-Meier survival curves showed that patients with an LMR < 3.58 had a significantly lower 4-year survival rate in the entire cohort (71.7% vs. 88.5%, P < 0.001) and the PSM subset (73.2% vs. 81.4%, P = 0.002).ConclusionsA lower LMR (< 3.58) was associated with a higher risk of 4-year mortality and can potentially predict the long-term mortality of cardiac surgery patients.