Prognostic Value of Lactate/Albumin Ratio and NEWS-Lactate in Predicting Sepsis-Associated Acute Kidney Injury: A Retrospective Analysis

Abstract

Introduction: Sepsis-associated acute kidney injury (SA-AKI) is a frequent complication in critically ill patients and is associated with increased mortality. This study aimed to evaluate the prognostic value of the lactate/albumin ratio (LAR) and other albumin-based biomarkers in predicting SA-AKI.

Methods: A retrospective observational study was conducted on 564 patients with sepsis, divided into two groups based on the presence (n = 298) or absence (n = 266) of AKI. Clinical characteristics, laboratory parameters, and disease severity scores (SOFA, APACHE II, NEWS, NEWS-Lactate) were compared between groups. The predictive performance of each marker in detecting SA-AKI was assessed using receiver operating characteristic (ROC) curve analysis.

Results: Patients with SA-AKI had significantly higher levels of lactate (p = 0.001), procalcitonin (PCT) (p = 0.001), urea (p = 0.019), creatinine (p = 0.004), and lower albumin (p = 0.001) concentrations upon admission. The LAR demonstrated the highest discriminative performance among all tested markers, with an area under the curve (AUC) of 0.800 (95% confidence interval (CI): 0.765-0.835), sensitivity of 70.5% (95% CI: 64.9 - 75.6), and specificity of 70.3% (95% CI: 64.4 - 75.7) at a cut-off value of 0.101. NEWS-Lactate also showed good prognostic ability (AUC = 0.772, 95% CI: 0.734-0.809), sensitivity of 71.1% (95% CI: 65.6 - 76.2), and specificity of 63.2% (95% CI: 57.1 - 69.0) at a cut-off value of 7.11. Other indices, including serum creatinine/albumin ratio (sCAR), blood urea nitrogen/albumin ratio (BAR), and procalcitonin/albumin ratio (PAR), and procalcitonin (PCT) × lactate, yielded moderate AUCs. While NEWS alone showed limited predictive value (AUC = 0.508), both SOFA and APACHE II scores were significantly higher in the SA-AKI group.

Conclusion: It seems that, the LAR and NEWS-Lactate are promising biomarkers for early detection of SA-AKI and may outperform conventional severity scores and standalone laboratory parameters.

Keywords: Acute kidney injury; Biomarkers; Prognosis; Sepsis; Serum albumin.

Figure 1

Flow diagram of patient selection. CKD: chronic kidney disease; ESRD: end stage renal disease; SA-AKI: sepsis associated acute kidney injury.

Figure 2

The area under the receiver operating characteristics (ROC) curve of different biomarkers in predicting the sepsis-associated acute kidney injury (SA-AKI). LAR: Lactate/ Albumin; sCAR: Serum Creatinine/ Albumin; BAR: Blood Urea Nitrogen/ Albumin; PAR: Procalcitonin/ Albumin; PCT × Lactate: Procalcitonin × Lactate. SOFA: Sequential Organ Failure Assessment; APACHE II: Acute Physiology and Chronic Health Evaluation II; NEWS: National Early Warning Score; NEWSL: National Early Warning Score combined with Lactate; Ure: urea.