Lactate-to-Albumin Ratio for Predicting Intensive Care Unit Admission in Patients with Diabetic Foot Infection

Abstract

Background

Early identification of diabetic foot infection (DFI) patients at risk for clinical deterioration is critical for timely intervention. Serum lactate reflects tissue hypoperfusion, whereas hypoalbuminemia indicates systemic inflammation and poor nutritional status. The aim of this study is to evaluate the ability of the lactate-to-albumin ratio (LAR) to predict ICU admission in patients with DFI.

Methods

This retrospective study was conducted in the emergency department of a tertiary care center between 01.01.2022 and 01.01.2025. Adult patients (≥18 years) with confirmed DFI were included. DFI diagnosis was established in accordance with IWGDF/IDSA 2023 criteria. ¹ Patients with chronic liver failure, nephrotic syndrome, pregnancy, or incomplete records were excluded. LAR was calculated as lactate (mmol/L) divided by albumin (g/dL). The primary outcome was ICU admission, defined as direct admission from the emergency department based on clinical severity assessment. ROC analyses assessed the predictive performance of LAR compared with lactate and albumin. Multivariable logistic regression identified independent predictors of ICU admission.

Results

Among 494 patients (median age, 64 years; 40.3% female), 91 (18.4%) required ICU admission. ICU patients had higher lactate (2.5 vs 1.8 mmol/L, P < .001), lower albumin (3.2 vs 3.4 g/dL, P < .001), and higher LAR (0.8 vs 0.5, P < .001). LAR demonstrated the best discrimination for ICU admission (AUC, 0.717; 95% CI, 0.658-0.777), outperforming albumin (AUC, 0.626; P = .009) and similar to lactate (AUC, 0.702; P = .134). A cut-off of ≥0.73 yielded 57.1% sensitivity and 78.2% specificity. LAR (OR, 1.36; 95% CI, 1.16-1.58; P < .001), older age, lower mean arterial pressure, and lower ankle–brachial index were independent predictors of ICU admission.

Conclusions

The lactate-to-albumin ratio is a simple, cost-effective biomarker that independently predicts ICU admission in DFI patients and may aid early risk stratification. Although LAR did not demonstrate statistically superior discrimination over lactate alone, it integrates systemic metabolic stress with the host's inflammatory and nutritional reserve, offering a composite measure of physiological vulnerability in this high-risk population.