Serum Lactate as an Independent Predictor of In-Hospital Mortality in Intensive Care Patients

Purpose: The aim of this study was to check if serum lactate was independently associated with mortality among critically ill patients. Materials and Methods: This was a single-center, retrospective cohort study. All adult patients (>18 years of age) who had at least 1 measurement of lactate within 24 hours of admission to intensive care unit (ICU) between January 2002 and December 2017 were included in the analysis. Patients were stratified into 3 groups: those with a serum lactate of <2 mmol/L (normal level), 2 to 4 mmol/L (intermediate level), and >4 mmol/L (high level). The primary outcome was in-hospital mortality. Secondary outcomes included ICU and hospital lengths of stay and mechanical ventilation duration. To determine the association between lactate level and hospital mortality, bivariate and multivariate logistic regression analyses were performed. Results: Of the 16,447 patients admitted to the ICU, 8167 (49.65%) had normal levels, 4648 (28.26%) had an intermediate, and 3632 (22.09%) had high lactate levels. Hospital mortality was the highest in high lactate level, followed by the intermediate and the normal level group (47.4% vs 26.5% vs 19.6%;P< .0001). Intermediate and high lactate levels were independent predictors of hospital mortality (odds ratio [OR], 1.32; 95% confidence interval [CI]: 1.20-1.46, and 1.94; 95% CI, 1.75-2.16, respectively) as well as ICU mortality (OR, 1.47; 95% CI, 1.30-1.66 and 2.56; 95% CI, 2.27-2.88, respectively). Conclusions: Intensive care unit serum lactate is associated with increased ICU and hospital mortality, independent of comorbidities, organ dysfunction, or hemodynamic status.