Association between lactate/albumin ratio and 28-day all-cause mortality in critically ill patients with acute myocardial infarction

Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality worldwide. Early identification of high-risk patients is crucial for timely interventions and improved outcomes. The lactate/albumin ratio (LAR) has been suggest as a significant correlate for assessing the risk of mortality in critically ill patients. This study aimed to utilize the American eICU Collaborative Research Database to explore the association between baseline LAR and all-cause mortality within 28 days in ICU of critically ill patients diagnosed with AMI. We conducted a retrospective cohort study of 989 AMI patients from the eICU Collaborative Research Database. Patients were included based on ICD-9 code 410 and the universal definition of AMI. LAR was calculated as the ratio of baseline lactate to albumin levels within the first 24 h of ICU admission. The outcome was all-cause mortality within 28 days after ICU admission. Multivariable logistic regression models were used to evaluate the independent association between LAR and the risk of death, adjusting for potential confounders including demographics, comorbidities, vital signs, and laboratory parameters. Subgroup analyses and nonlinear modeling were performed to further explore the relationship. Of the 989 AMI patients, 171 (17.3%) died within 28 days after ICU admission. Patients who died had significantly higher LAR compared to survivors (1.66 vs. 0.96, p < 0.001). Multivariable analysis showed that each unit increase in LAR was associated with a 2.15-fold higher risk of all-cause mortality within 28 days after ICU admission (95% CI: 1.64-2.83, p < 0.001). Subgroup analyses confirmed the consistent association across different patient characteristics. Nonlinear modeling revealed a threshold effect, where LAR above 2.15 was no longer significantly associated with mortality. Kaplan-Meier survival analysis demonstrated lower survival probabilities for patients with higher LAR(1.0526-5.8235). The findings suggest that a higher LAR was associated with an increased risk of 28-day all-cause mortality for critically ill patients with AMI after ICU admission.