The Lactate/Hematocrit Ratio and Prognosis in ICU Patients with Acute Myocardial Infarction: A Retrospective Cohort Study

Objective To assess the association between the lactate to hematocrit ratio (LHR) at ICU admission and all cause mortality at 28-day and 360-day in patients with acute myocardial infarction (AMI) and to test its added value beyond established severity scores. Methods This retrospective study used data from the Medical Information Mart for Intensive Care IV database (MIMIC IV, version 3. 1). Adult ICU patients with AMI were included. We applied multivariable Cox regression, receiver operating characteristic (ROC) analysis, Kaplan-Meier curves, subgroup analyses, and sensitivity analyses to examine the relation between admission LHR and 28-day and 360-day mortality. Results A total of 2884 patients were included. Compared with Q1, patients in Q4 had higher mortality risk at 28-days (hazard ratio [HR] 1. 799, 95% confidence interval [CI] 1. 304 to 2. 481, P < 0. 001) and at 360-days (HR 1. 520, 95% CI 1. 152 to 2. 006, P = 0. 003). The area under the ROC curve (AUC) for LHR was 0. 802 for 28-day mortality and 0. 796 for 360-day mortality. Adding LHR to existing scores improved model discrimination and reclassification as shown by the integrated discrimination improvement (IDI) and the net reclassification improvement (NRI). Restricted cubic spline (RCS) analysis showed an almost linear dose response relation between LHR and mortality. Findings were consistent in the complete case analysis. Conclusion LHR is an independent risk factor for short term and long term mortality in ICU patients with AMI. Adding LHR to current models improves prediction and may help identify high risk patients. Trial registration: Not applicable.