Neutrophil-lymphocyte ratio predicts disease severity and outcome after lower extremity procedures

Abstract

Objective: Neutrophil-lymphocyte ratio (NLR) has been associated with inferior outcomes after lower extremity interventions. NLR has been associated with systemic inflammation and atherosclerotic burden. We examined NLR, severity of peripheral artery disease (PAD), and outcomes after endovascular or open surgical procedures.

Methods: Inpatients undergoing lower extremity procedures (2008-2016) were selected from Cerner Health Facts database (Cerner Corporation, North Kansas City, Mo) using International Classification of Diseases, Ninth Revision procedure codes. Disease severity was grouped into claudication, rest pain, and tissue loss. Outcomes were identified using International Classification of Diseases, Ninth Revision codes. NLR was calculated preoperatively and postoperatively. A χ² analysis and multivariable logistic regression were performed. A receiver operating characteristic curve analysis was used to determine the cutoff for preoperative (low, <3.65; high, ≥3.65) and postoperative (low, <5.96; high, ≥5.96) NLR values.

Results: There were 3687 patients evaluated; 2183 (59%) underwent endovascular procedures and 1504 (41%) had open procedures. Compared with black patients, claudication was more frequent in white patients (81.7% vs 72.7%; P < .0001), and tissue loss was less common (12.9% vs 20.9%; P < .0001). NLR values were higher for patients with tissue loss than for patients with rest pain or claudication (4.89, 4.33, and 3.11, respectively; P < .0001). Open procedures were associated with higher postoperative NLR values than endovascular procedures (6.8 vs 5.2; P < .0001). Mean preoperative and postoperative NLR values were greater in patients with more severe PAD. Multivariable analysis demonstrated that preoperative high NLR was strongly associated with in-hospital death (odds ratio [OR], 5.4; 95% confidence interval [CI], 1.68-17.07), cardiac complications (OR, 2.9; 95% CI, 1.57-5.40), amputation (OR, 2.5; 95% CI, 1.65-3.87), renal failure (OR, 1.9; 95% CI, 1.18-2.93), respiratory complications (OR, 1.7; 95% CI, 1.09-2.76), and prolonged length of stay (OR, 1.9; 95% CI, 1.89-3.71).

Conclusions: Preoperative and postoperative NLR significantly increases with disease severity for PAD, providing further evidence of NLR as a biomarker of a patient's systemic inflammatory state. After adjustment for confounders, NLR still remained strongly associated with death and other adverse outcomes after intervention for PAD. Further study of the clinical association of NLR with other vascular disorders, such as symptomatic carotid stenosis and symptomatic and ruptured aortic aneurysmal disease, is planned to guide individualized treatment to prevent stroke or aneurysm rupture.

Keywords: Lower extremity procedures; Neutrophil-lymphocyte ratio; Peripheral arterial disease; Vascular surgery.

Figure 1.

Receiver-operating curve characteristics AUC = area under the curve; NLR = neutrophil-lymphocyte ratio

Figure 2.

Pre- and post-operative NLR by PAD severity Denotes significant difference compared with claudication within each time period.

Figure 3.

Pre- and post-operative NLR by procedure type and PAD severity. Denotes significant difference compared with claudication within each time period.