The Predictive Role of BUN/Creatinine Ratio and Inflammatory Markers in Determining Amputation Risk in Acute Limb Ischemia Patients

Abstract

Objective

Acute limb ischemia (ALI) is a time-sensitive vascular emergency that often presents to the emergency department and can result in limb loss or mortality if not managed promptly. Identifying simple, cost-effective biomarkers at the time of initial emergency department evaluation could facilitate early risk stratification and guide timely intervention, particularly in resource-limited settings. This study aimed to evaluate the predictive value of three readily available laboratory markers—neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and blood urea nitrogen (BUN)/creatinine ratio—for assessing amputation risk in patients with ALI.

Methods

We conducted a single-center, retrospective cross-sectional study of 138 patients diagnosed with ALI who presented to the emergency department between January 2020 and January 2023. Demographic and laboratory data were collected. ROC analysis was performed to evaluate the predictive performance of NLR, PLR, and BUN/creatinine ratio for amputation risk, and multivariate logistic regression identified independent predictors.

Results

Among the biomarkers analyzed, the BUN/creatinine ratio demonstrated the highest predictive performance for amputation risk (AUC: 0.727, sensitivity: 69.0%, specificity: 68.8%), although the discriminative ability was only moderate. NLR (AUC: 0.666) and PLR (AUC: 0.647) also showed associations with amputation risk, though with lower predictive values. Female gender emerged as an additional independent predictor of amputation risk (OR: 4.16, 95% CI: 1.47-11.81, P = .007).

Conclusions

Our findings suggest that the BUN/creatinine ratio may serve as an accessible biomarker with moderate predictive performance, whose main utility may lie in helping to exclude patients at low risk of amputation. While NLR and PLR also showed potential value, further prospective multicenter studies are required to validate their clinical applicability.