Preoperative neutrophil-to-lymphocyte ratio and 30-day death or major amputation in acute limb ischemia: a retrospective cohort study

Background Acute limb ischemia (ALI) couples abrupt arterial occlusion with innate immune activation, endothelial injury, and reperfusion-related inflammation. The neutrophil-to-lymphocyte ratio (NLR) integrates neutrophilia and stress-associated lymphopenia, but its value for identifying patients at risk of early death or major limb loss requires further evaluation. Methods We retrospectively studied 115 adults treated for ALI at a single tertiary center. The primary outcome was the first occurrence of all-cause death or major amputation within 30 days. Associations and discrimination were evaluated using receiver operating characteristic analysis, Kaplan–Meier analysis, and Cox regression. As a secondary exploratory within-cohort analysis, incremental discrimination was assessed by comparing Rutherford classification alone with Rutherford classification plus NLR. Results Sixteen patients (13.9%) experienced the composite outcome, including 5 deaths and 11 major amputations. Median NLR was 8.9 [interquartile range, 6.3-14.4] in patients with an event and 3.3 [2.4–5.5] in those without an event ( P < 0.001). The composite-outcome area under the curve was 0.886 (95% confidence interval [CI], 0.810–0.961). The cohort-derived candidate cutoff was 5.7, with apparent sensitivity of 87.5% and specificity of 76.8% when selected and evaluated in the same cohort. Each doubling of NLR remained associated with higher risk after Rutherford adjustment (adjusted hazard ratio, 2.64; 95% CI, 1.55–4.51; P < 0.001). In an exploratory analysis developed and evaluated in the same cohort, adding NLR to Rutherford classification increased the apparent 30-day AUC from 0.835 to 0.968 (delta AUC, 0.133; descriptive paired DeLong P = 0.0015). Conclusion Preoperative NLR was associated with the 30-day composite of death or major amputation and showed apparent early discrimination in this cohort. Its candidate cutoff and exploratory complementary value require external validation.