Prognostic Value of the Lactate-to-Albumin Ratio for Predicting Intensive Care Unit Admission in Patients with Diabetic Foot Infection: A Retrospective Cohort Study

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. Thus, the aim of this study was to evaluate the ability of the lactate-to-albumin ratio (LAR) to predict ICU admission. Methods: This retrospective study was conducted in the emergency department of a tertiary care center between [start date] and [end date]. Adult patients (≥ 18 years) with confirmed DFI and available admission lactate and albumin measurements were included. Patients with chronic liver failure, nephrotic syndrome, pregnancy, or incomplete records were excluded. Demographics, comorbidities, vital signs, and laboratory data were retrieved from electronic records. LAR was calculated as lactate (mmol/L) divided by albumin (g/dL). The primary outcome was intensive care unit (ICU) admission. Receiver operating characteristic (ROC) analyses assessed the predictive performance of LAR compared with lactate and albumin. Independent predictors of ICU admission were identified using multivariable logistic regression. 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 (area under the curve [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 (odds ratio [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.