Shock-Lactate Index Predicts 28-Day Mortality in Sepsis-Associated AKI

Overview

This retrospective study analyzed data from the MIMIC-IV database to evaluate the Shock-Lactate Index (SLI) as a predictor of 28-day mortality in patients with sepsis-associated acute kidney injury (SA-AKI). The findings demonstrate that SLI, combining heart rate, systolic blood pressure, and lactate levels, independently correlates with mortality risk, offering a valuable tool for early identification of high-risk patients.

Background

Sepsis is a critical condition characterized by organ dysfunction due to infection, with septic shock representing its most severe form. Acute kidney injury (AKI) frequently complicates sepsis, occurring in up to 60% of cases and significantly increasing mortality. Traditional biomarkers such as neutrophil-to-lymphocyte ratio and inflammatory markers provide prognostic information but may not detect occult circulatory failure early. The Shock Index (SI) and lactate levels individually predict adverse outcomes, and their combination as the Shock-Lactate Index (SLI) may enhance early risk stratification in SA-AKI.

Data Highlights

The study utilized the MIMIC-IV database (2008–2019) including adult ICU patients diagnosed with sepsis per Sepsis-3 criteria and developing AKI after ICU admission. Inclusion required first SLI measurement within 24 hours of ICU admission. Data extracted included demographics, vital signs, severity scores (SAPSII, SIRS, APSIII, SOFA), and laboratory values. Patients with incomplete or abnormal data were excluded to ensure data integrity.

Key Findings

• SLI is calculated as (Heart Rate / Systolic Blood Pressure) × Lactate level.
• Higher SLI values were significantly associated with increased 28-day mortality in SA-AKI patients.
• SLI demonstrated independent predictive value beyond traditional severity scores and biomarkers.
• Combining SI and lactate improved early detection of occult circulatory failure compared to either parameter alone.
• SLI may facilitate timely resuscitation and resource allocation in critically ill septic patients with AKI.

Clinical Implications

The Shock-Lactate Index offers clinicians a rapid bedside tool to identify sepsis patients with AKI at elevated risk of mortality, enabling earlier intervention. Incorporating SLI into routine assessment may improve prognostic accuracy and guide therapeutic decisions, potentially improving patient outcomes. Monitoring SLI within the first 24 hours of ICU admission is recommended for optimal risk stratification.

Conclusion

SLI is a valuable independent predictor of 28-day mortality in patients with sepsis-associated AKI, enhancing early recognition of shock and guiding clinical management. Its integration into ICU protocols could improve prognostication and patient care.

References

1. Singer et al., 2016 -- The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)
2. MIMIC-IV Database, Version 3.1 -- Medical Information Mart for Intensive Care