Background: Serum lactate is widely used as a biomarker of tissue hypoperfusion in critically ill patients. While elevated baseline lactate levels are associated with adverse outcomes, dynamic changes in lactate concentration (particularly early lactate clearance) may provide superior prognostic information. Data regarding the predictive value of early lactate clearance in secondary-care medical intensive care units (ICUs) remains limited. We aim to evaluate the association between early (0–6-hour) lactate clearance and in-hospital mortality in adult patients admitted to a secondary-care medical ICU. Methods: This retrospective cohort study included 114 adult patients admitted to a general medical ICU between 2018 and 2019. Patients with serum lactate measured within the first hour of ICU admission and repeated at approximately 6 hours were eligible. Lactate clearance was calculated as: (Lactate0 – Lactate1) / Lactate0 × 100. The primary outcome was in-hospital mortality. Secondary outcomes included ICU length of stay, mechanical ventilation requirement, and acute kidney injury (AKI). Multivariable logistic regression analysis was performed to assess the independent association between lactate clearance and mortality, adjusting for baseline lactate, SOFA score, age, and vasopressor use. Results: The cohort consisted of 59 males (51.8%) and 55 females (48.2%), with a median age of 65 years (interquartile range IQR, 52–78 years; range, 18–94 years). Mean baseline lactate was 3.82 ± 2.14 mmol/L, and mean lactate clearance was 18.7 ± 21.3%. Patients with low lactate clearance (<10%) had significantly higher mortality compared with those achieving ≥20% clearance (64.3% vs. 15.9%, p<0.001). In multivariable analysis, lactate clearance remained independently associated with reduced mortality (OR 0.78 per 10% increase; 95% CI 0.67–0.91; p=0.002). The model demonstrated good discrimination (AUC 0.87). Lower lactate clearance was also associated with longer ICU stays, increased mechanical ventilation requirements, and a higher incidence of AKI, though the observational nature of this study precludes establishing causality. Conclusions: Early lactate clearance is a strong and independent predictor of in-hospital mortality in a secondary-care medical ICU population. Dynamic lactate assessment within the first 6 hours may improve early risk stratification and guide resuscitation strategies in critically ill patients.
Bektaş et al. (Tue,) studied this question.