The neutrophil-lymphocyte ratio: A promising predictor of mortality in coronary care unit patients — A cohort study

Severe inflammation causes poor outcomes in coronary care unit (CCU) patients. The neutrophil-lymphocyte ratio (NLR), a biomarker used to monitor inflammation and the immune response, can predict a poor prognosis in various diseases. However, it remains unclear whether the NLR is associated with all-cause mortality in CCU patients. This study investigated the association between the NLR and CCU outcomes. Clinical data were extracted from the Multiparameter Intelligent Monitoring in Intensive Care III (MIMIC-III) database, which contains health data for over 50,000 patients. The primary outcome was 30-day mortality and the secondary outcome was 90-day mortality. Cox proportional hazard models were used to reveal the associations between NLR and outcomes. Multivariate analyses were used to control for confounders. We enrolled 3563 CCU patients. For 30-day mortality, the hazard ratio (HR) (95% confidence interval [CI]) for the second (NLR 4.80–10.08) and the third (NLR ≥ 10.09) tertiles were 1.57 (1.24, 1.97) and 2.76 (2.23, 3.41), respectively, compared to the first tertile (NLR < 4.80). In the model adjusted for multiple confounders, the fifth quintile (NLR ≥ 14.17) showed a slightly lower mortality risk [HR (95% CI) 1.44 (1.07, 1.94)] compared to the fourth (NLR 8.82–14.16) [HR (95% CI) 1.55 (1.15, 2.10)]. A similar trend was observed for 90-day mortality. The interactions between the acute kidney injury, respiratory failure, and pneumonia subgroups and 30-day mortality were significant. The NLR was an independent predictor of 30- and 90-day mortality for CCU patients. The NLR is a promising clinical biomarker as an integrated, readily available predictor of CCU mortality.