Neutrophil to Lymphocyte Ratio is an Independent Predictor of 30 Day Death or Amputation in Patients Submitted to Revascularisation for Acute Limb Ischaemia

Abstract

Objective: Biomarkers can aid not only in the timing and treatment selection for acute limb ischaemia (ALI), but also in anticipation of complications. Therefore, this study aimed to evaluate the value of pre-operative inflammatory markers, specifically the neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR), for predicting an adverse outcome after urgent revascularisation for ALI. Methods: The study included 345 patients submitted to urgent revascularisation for ALI between 2009 and 2019. NLR and PLR were evaluated pre-operatively, along with other known prognostic factors. The primary outcome was 30 day death or major amputation. Results: The mean follow up was 23.1 (3.1 – 52.2) months. Advanced age (OR 1.05 [1.01 – 1.09], p = .027), diabetes (OR 2.63 [1.14 – 6.06], p = .024), Rutherford grade IIb (OR 5.51 [2.11 – 14.42], p = .001), higher NLR (OR 1.28 [1.12 – 1.47], p < .001), and fasciotomy (OR 3.44 [1.14 – 10.34], p = .028) were independent predictors of the specified outcome, whereas pre-procedural statin or anticoagulant medication had a protective effect (OR 0.23 [0.53 – 0.96], p = .045 and OR 0.20 [0.05 – 0.84], p = .027, respectively). PLR did not show an independent effect in this population. A cutoff point NLR level of 5.4 was demonstrated to have a 90.5% sensitivity and 73.6% specificity for 30 day death or amputation. In this population, Kaplan−Meier analysis showed that patients with a pre-procedural NLR ≥ 5.4 had significantly lower 30 day, six month, and one year amputation free survival when compared with those with NLR < 5.4 (50.3 ± 0.04% vs. 96.4 ± 0.05%; 33.0 ± 0.04% vs. 89.2 ± 0.02%; and 28.5 ± 0.04% vs. 82.2 ± 0.03%, log rank < 0.001). Conclusion: Elevated pre-operative NLR seems to be associated with an adverse outcome in patients requiring urgent revascularisation for ALI. This readily available, easily calculated, and inexpensive inflammatory marker could become a useful tool for pre-procedural risk stratification of patients with ALI.