Admission lactate-to-hemoglobin ratio and mortality in critically ill patients with type 1 acute myocardial infarction: A mimic-iv database study

Abstract

Background The lactate-to-hemoglobin ratio (LHBR) integrates information on metabolic stress and oxygen-carrying capacity. This study aimed to evaluate the association between admission LHBR and mortality among critically ill patients with type 1 acute myocardial infarction (AMI). Methods We conducted a retrospective cohort study using the MIMIC-IV database (version 3.1) and included adult patients admitted to the intensive care unit (ICU) with type 1 AMI. LHBR was calculated from the first lactate and hemoglobin levels around ICU admission. The primary outcome was 30-day mortality; secondary outcomes were 60-, 90-, and 180-day mortality. Associations were evaluated using restricted cubic spline analyses, Cox proportional hazards regression models, and receiver operating characteristic (ROC) curve analyses. Results A total of 4,651 patients were included and categorized into LHBR tertiles using cutoffs of ≤0.127 (T1), >0.127–0.209 (T2), and >0.209 (T3). Restricted cubic spline analyses showed significant nonlinear associations between LHBR (as well as the natural logarithm-transformed LHBR) and all mortality outcomes (all P-nonlinear <0.05). In the adjusted purposeful selection model, both intermediate (T2) and high (T3) LHBR tertiles were associated with increased 30-day mortality compared with the lowest tertile (T1) (T2 vs T1: HR 1.32, 95% CI 1.07–1.64; T3 vs T1: HR 2.05, 95% CI 1.66–2.52). Comparable findings were observed for 60-day mortality (HRs 1.29 and 1.94), 90-day mortality (HRs 1.30 and 1.89), and 180-day mortality (HRs 1.26 and 1.75), respectively. Admission LHBR demonstrated slightly better discrimination for 30-day mortality than either lactate or hemoglobin alone. Conclusions Higher admission LHBR was associated with increased short-term and long-term mortality in critically ill patients with type 1 AMI. Further studies are warranted to validate these findings and determine the clinical utility of LHBR in this population.