The systemic immune-inflammation index is an independent predictive factor in predicting major amputation in chronic limb-threatening ischemia.

Abstract

BackgroundLower extremity peripheral arterial disease (LEAD) is characterized by the narrowing and occlusion of arteries in the lower extremities. The most severe form of LEAD is chronic limb-threatening ischemia (CLTI), which carries a poorer prognosis for major amputation. The systemic immune-inflammation index (SII) is an index developed to simultaneously reflect the inflammatory and immunothrombosis status of patients, based on platelet counts and the neutrophil-to-lymphocyte ratio.ObjectiveOur study aimed to investigate the relationship between elevated SII and major limb amputation.MethodThe study included 140 patients with foot wounds (Rutherford 5 or 6) due to LEAD who were scheduled for endovascular intervention between 2018 and 2023. Major amputation was required in 27 patients (19.2%). The neutrophil-to-lymphocyte ratio (2.1/2.8/3.8 vs 3.8/6.6/9.3, p < .001), platelet-to-lymphocyte ratio (103.8/128.8/162.9 vs 132.8/212.3/314.6, p < .001), and SII (527/720/1055.5 vs 1108/1951/3807, p < .001) were higher in the major amputation group. ROC curve analysis determined that the optimal cut-off value for SII to predict major amputation in LEAD patients was 1018, with a sensitivity and specificity of 81% and 73%, respectively (AUC: 0.84, 95% CI: 0.74-0.92, p < .001). Logistic regression analysis showed that high SII (OR = 1.001, 95% CI = 1-1.001, p = .009) was identified as an independent predictor of major amputation in LEAD patients.ConclusionThis study establishes that a high SII value is associated with major amputation in LEAD patients with foot wounds.ResultSII is a valuable and straightforward parameter for predicting major amputation risk and guiding treatment decisions in LEAD patients.