Neutrophil-to-Lymphocyte Ratio Could Predict Outcome in Patients Presenting with Acute Limb Ischemia

Abstract

Introduction: Acute limb ischemia (ALI), classified according to Rutherford's classification (RC), is a vascular emergency burdened by high rates of mortality and morbidity. The need of new and different prognostic values for ALI has emerged, and, among all, the neutrophil-to-lymphocyte ratio (NLR) has been proven as a strong outcome predictor in vascular disease. The aim of this study is to investigate the role of preoperative NLR in predicting clinical outcomes in patients presenting acute limb ischemia.

Material and methods: A single-center retrospective study was conducted between January 2015 and December 2019. Demographic and clinical characteristics, procedural technical aspects, postoperative and early (up to 30-day) outcomes were recorded. All enrolled patients were categorized into low- and high-NLR at baseline, using a cut-off value of 5. Study outcomes were 30-day all-cause mortality and amputation rates.

Results: A total of 177 ALI patients were included in the final analysis (6 RC I, 44 RC IIA, 108 RC IIB, and 19 RC III), 115 males (65%), mean age 78.9 ± 10.4 years. Mean NLR at hospital presentation was 6.65 ± 6.75 (range 0.5-35.4), 108 (61.1%) patients presented a low-NLR, 69 (38.9%) a high-NLR. Immediate technical success was achieved in 90.1% of cases. At 30 days, freedom from amputation and freedom from death rates were 87.1% and 83.6%, respectively. At the univariate analysis, amputation (p < 0.0001, OR: 9.65, 95%CI: 3.7-25.19), mortality (p = 0.0001, OR: 9.88, 95%CI: 3.19-30.57), and cumulative event rates (p < 0.001, OR: 14.45, 95%CI: 6.1-34.21), were significantly different between the two groups according to NLR value. Multivariate analysis showed that a high baseline NLR value was an independent predictor of unfavorable outcomes in all enrolled patients. Consistently, at ROC analysis, a preoperative NLR > 5 was strongly associated with all outcome occurrences.

Conclusion: Preoperative NLR value seems to be strongly related to ALI outcomes in this unselected population. The largest series should be evaluated to confirm present results.

Keywords: acute limb ischemia; amputation; biomarkers; neutrophil to lymphocyte ratio; vascular medicine.

Figure 1

Enrollment flowchart.

Figure 2

ROC curve analysis (A) for NLR with respect to amputation rate in all patients (c-statistic 0.823), (B) for NLR with respect to mortality in all patients (c-statistic 0.776), (C) for NLR with respect to amputation + mortality rate in all patients (c-statistic 0.840), (D) for NLR with respect to amputation rate in RC IIA patients (c-statistic 0.845), (E) for NLR with respect to mortality in RC IIA patients (c-statistic 0.752), (F) for NLR with respect to amputation + mortality rate in RC IIA patients (c-statistic 0.845), (G) for NLR with respect to amputation rate in RC IIB patients (c-statistic 0.798), (H), for NLR with respect to mortality in RC IIB patients (c-statistic 0.751), and (I) for NLR with respect to amputation + mortality rate in RC IIB patients (c-statistic 0.798).; ROC: receiver-operating characteristic; NLR: neutrophil-to-lymphocyte ratio; RC: Rutherford class.