[Monocyte/lymphocyte ratio as a predictor of 30-day mortality and adverse events in critically ill patients: analysis of the MIMIC-III database].

OBJECTIVE To investigate the correlation of monocyte/lymphocyte ratio (MLR) with the prognosis and adverse event in critically ill patients. METHODS Basic information of patients were extracted from Medical Information Mart for Intensive Care-III (MIMIC-III), including demographics, blood routine, biochemical indexes, systemic inflammatory response syndrome score (SIRS), sequential organ failure assessment (SOFA) score, and outcome, etc. MLR on the first day of intensive care unit (ICU) admission was calculated. The receiver operating characteristic curve (ROC curve) was applied to evaluate the prognostic value of MLR on the 30-day mortality and its cut-off value. According to the cut-off value, the patients were divided into two groups, and the differences between the groups were compared. Logistic regression model was used to analyze the relationship of MLR with 30-day mortality, continuous renal replacement therapy (CRRT), mechanical ventilation, the length of ICU stay, and total hospitalization time. RESULTS (1) A total of 43 174 critically ill patients were included. ROC curve showed that area under ROC curve (AUC) of MLR in predicting 30-day mortality was 0.655 [95% confidence interval (95%CI) was 0.632-0.687]. The cut-off value of MLR calculated according to the maximum Yoden index was 0.5. There were 16 948 patients with MLR ≥ 0.5 (high MLR group) and 26 226 patients with MLR 5 days, total hospitalization time > 14 days, CRRT and mechanical ventilation > 5 days were significantly higher in high MLR group (30-day mortality: 20.0% vs. 8.3%, length of ICU stay > 5 days: 33.2% vs. 20.4%, total hospitalization time > 14 days: 33.7% vs. 16.2%, CRRT: 3.6% vs. 0.7%, mechanical ventilation > 5 days: 18.4% vs. 5.7%), with statistically significant differences (all P 5 days (OR = 2.45, 95%CI was 2.21-2.72), the length of ICU stay > 5 days (OR = 2.29, 95%CI was 2.10-2.49), and total hospitalization time > 14 days (OR = 2.28, 95%CI was 2.08-2.49), all P < 0.001. CONCLUSIONS Retrospective analysis of large sample shows that MLR elevation is an independent risk factor for 30-day mortality, usage of CRRT, prolonged mechanical ventilation time, prolonged hospitalization, prolonged length of ICU stay. MLR can be used for risk stratification of severe patients.