Lactate Kinetics and Procalcitonin Clearance as Predictors of 28-Day Mortality in Patients With Sepsis Admitted to a Medical Intensive Care Unit: A Prospective Observational Study

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Background: Sepsis-associated organ failure is a major cause of mortality in intensive care units (ICUs) worldwide.Timely risk stratification using reliable biological markers may help identify patients at increased risk of adverse outcomes and support clinical decision-making.This study evaluated the prognostic performance of serial lactate measurements and procalcitonin (PCT) clearance for predicting 28-day mortality in patients with sepsis admitted to a tertiary-level medical ICU.Materials and methods: This single-center prospective observational study was conducted in the Department of Critical Care Medicine, Jaypee Hospital (now Max Super Speciality Hospital), Sector 128, Noida, Uttar Pradesh, India, over an 18-month period from August 2022 to February 2024.Adults aged ≥18 years admitted with sepsis, operationally defined as an increase in the Sequential Organ Failure Assessment score of ≥2 points, were consecutively enrolled (n = 100).Whole-blood lactate was measured at admission and at six, 12, and 24 hours, while PCT was measured at admission and on day 3. Absolute lactate clearance, relative lactate clearance (RLC), lactate clearance rate (LCR), and PCT clearance were calculated.The primary outcome was all-cause mortality within 28 days.Receiver operating characteristic curve analysis was used to evaluate discriminatory performance and identify exploratory cutoffs.Results: The mean age was 57.8 ± 13.6 years, and 56% of participants were male.Twenty-one patients (21%) died within 28 days.Compared with survivors, nonsurvivors had higher admission lactate concentrations (median, 8.6 mmol/L (IQR, 6.4-12.4) vs. 3.7 mmol/L (IQR, 2.6-4.4);p < 0.0001) and admission PCT levels (median, 100 ng/mL (IQR, 44.5-100) vs. 11.5 ng/mL (IQR, 5.5-27.3);p < 0.0001).PCT clearance demonstrated an apparent AUC of 1.000 (95% CI, 0.964-1.000)at an exploratory cutoff of ≤38.65%.RLC and LCR each had an AUC of 0.999, while 24-hour lactate had an AUC of 0.996.These estimates were obtained and evaluated in the same cohort and have not been independently validated.Conclusions: Serial lactate measurements and PCT clearance may provide useful prognostic information in ICU patients with sepsis.Although these biomarkers demonstrated high apparent discriminatory performance in this cohort, the identified cutoffs are exploratory and have not been independently validated.Larger, multicenter studies are needed to establish their reproducibility and clinical utility before these thresholds can be considered for clinical implementation.