Risk stratification for low extremity amputation in critical limb ischemia patients who have undergone endovascular revascularization: A survival tree analysis

Patients with peripheral artery disease (PAD) are a heterogeneous population and differ in risk of mortality and low extremity amputation (LEA), which complicates clinical decision-making. This study aimed to develop a simple risk scale using decision tree methodology to guide physicians in managing critical limb ischemia (CLI) patients who will benefit from endovascular therapy (EVT).A total of 736 patients with CLI, Rutherford classification (RC) stage ≥4, and prior successful EVT were included. Variables significantly associated with LEA by univariate analysis (P < .05) were selected and put into classification tree analysis using the Classification and Regression Tree (CART) model with a dependent variable, amputation, and depth of tree = 3. Four risk groups were generated according to the order of amputation rate. The amputation-free survival (AFS) times between groups were compared using the Kaplan-Meier curve with the log-rank test.Patients were classified as high risk for amputation (G4) (WBC counts ≥10,000/μl, and platelet-lymphocyte ratio (PLR) ≥130.337); intermediate risk group 1 (G3) (WBC < 10,000/μl and RC stage before EVT > 5); intermediate risk group 2 (G2) (WBC count ≥ 10,000/μl, and PLR < 130.337) and low-risk group (G1) (WBC < 10,000/μl, RC before EVT ≤ 5). G2, G3, and G4 risk groups had shorter AFS time (range, 58.7 to 65.5 months) than the G1 risk group (100 months) (P < .05). Risk of LEA was significantly higher in the G4, G3, and G2 groups than in the G1 group (P ≤ .05). The G4 group had the highest risk of amputation (odds ratio = 6.84, P < .001).This simple risk scale model can help healthcare professionals more easily identify and appropriately treat patients with CLI who are at different levels of risk for LEA following endovascular revascularization.