Prognostic value of systemic inflammatory indices for restenosis and limb salvage after below-the-knee endovascular revascularization in diabetic critical limb-threatening ischemia

Abstract

Systemic inflammation has been implicated in adverse outcomes following endovascular revascularization for chronic limb-threatening ischemia (CLTI). This study aimed to evaluate the prognostic value of systemic inflammation–based indices, particularly the systemic immune–inflammation index (SII), for predicting restenosis and limb-related outcomes after below-the-knee (BTK) endovascular revascularization in diabetic CLTI patients. This retrospective cohort study included consecutive diabetic patients who underwent BTK endovascular revascularization for CLTI between January 2022 and October 2025. Demographic, clinical, procedural, and laboratory data were collected from electronic medical records. Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and SII were calculated from complete blood count parameters obtained within 24 h before and 48–72 h after the procedure. Restenosis at 6 months and limb salvage were the primary outcomes. Receiver operating characteristic (ROC) analysis was used to assess the discriminative ability of inflammatory indices. Multivariable logistic regression analysis was performed to identify independent predictors of restenosis. A total of 210 patients were included, of whom 161 (76.7%) achieved technical success and constituted the cohort for restenosis analysis. Among these patients, 63 (39.1%) developed restenosis at 6 months. Major amputation occurred in 42 patients (20.0%) in the overall cohort. Patients who developed restenosis had significantly higher pre-procedural SII than those without restenosis (2152.88 ± 765.32 vs. 1344.06 ± 680.17; p  < 0.001). ROC analysis demonstrated that pre-procedural SII had the highest discriminative performance among the evaluated variables (AUC 0.786, 95% CI 0.717–0.854). In multivariable analysis restricted to technically successful procedures, each 1000-unit increase in pre-procedural SII remained independently associated with higher odds of 6-month restenosis after adjustment for lesion length, calcification grade, ankle–brachial index, drug-coated balloon use, WIfI clinical stage, and estimated glomerular filtration rate (adjusted OR 2.31, 95% CI 1.18–4.49; p  = 0.014). Pre-procedural SII was independently associated with 6-month restenosis and demonstrated moderate-to-good discriminative performance following technically successful BTK endovascular revascularization in diabetic CLTI patients. These findings support its potential role as an adjunctive biomarker for pre-procedural risk stratification, although external validation is required.