The Neutrophil-to-Lymphocyte Ratio is a Prognostic Biomarker of Amputation and Mortality Among Patients Suffering an Acute Limb Ischemia Event

Abstract

Introduction: The neutrophil-to-lymphocyte ratio (NLR) is a novel simple biomarker of inflammation. It has emerged as a predictor of poor prognosis in cancer and cardiovascular disease, but little is known of its prognostic value in acute limb ischemia (ALI) events. The aim of this study was to evaluate the correlation between the preoperative NLR and the prognosis of patients with an IAE. Methods: Retrospective cohort study of all consecutive patients with an ALI event attended in a tertiary university hospital (referral population 350.000 inhabitants) between 2007 and 2017. ALI secondary to trauma or bypass/stent occlusions were excluded. Analyzed outcomes were major limb amputation and survival. Statistics: Cox regression analysis adjusted by confounding factors. Results: The study group included 265 patients (mean age 78; 49% male) with ALI, of which 172 (64.9%) were attributed to arterial embolism and 93 (35.1%) to an acute arterial thrombosis. Treatment consisted of anticoagulation in 31 (11.7%) patients, revascularization in 226 (85.3%), including (alone or in combination) 173 embolectomies/thrombectomies, 18 fibrinolysis, 12 stentings and 52 bypasses, and primary major amputation in 8 (3%) cases. The mean follow-up was 2.8 years, and there were 17 (6.4%) major amputations (including primary ones) and 153 (57.7%) deaths. Limb salvage and survival rates at 30 days, 6 months and 1 and 3 years were 94.4%, 93.2%, 92.6% and 92.6%, and 84.5%, 72.3%, 66.1% and 52.1%, respectively. The NLR was independently associated with a poorer long-term survival rate (HR per unit of NLR = 1.025, p=0.032) after adjustment for age, diabetes, atrial fibrillation, stroke, acute arterial thrombosis, any limb ischemic neurological impairment and hospitalization for any other reason simultaneous to the ALI. Similarly, a NLR>3 (the ratio was categorized because of the reduced number of major amputation events) was marginally associated with a lower limb-salvage survival rate (HR = 6.7, p=0.066) after adjustment for severe limb ischemic neurological impairment, acute arterial thrombosis and treatment delay>24 hours. Conclusion: The NLR is associated with a higher risk of major amputation and survival among patients suffering an ALI event. Therefore it could be considered as an easily available prognostic biomarker. Disclosure: Nothing to disclose