Neutrophil-to-Lymphocyte Ratio and Its Association with Critical Limb Ischemia in PAOD Patients

BACKGROUND: The Neutrophil-to-Lymphocyte ratio (NLR) is an easy to perform test from the white blood cell count. An increase in NLR has been associated with vascular endpoints reflecting inflammation in atherosclerotic lesions. Atherosclerosis is a global threat and vascular endpoints, like myocardial infarction or critical limb ischemia (CLI), are a leading cause of death in industrialized countries. We therefore investigated NLR and its association with CLI and other vascular endpoints in peripheral arterial occlusive disease (PAOD) patients. METHODS AND FINDINGS: We evaluated 2121 PAOD patients treated at our institution from 2005 to 2010. NLR was calculated and the cohort was divided into tertiles according to the NLR. An optimal cut-off value for the continuous NLR was calculated by applying a receiver operating curve analysis to discriminate between CLI and non-CLI. In our cohort occurrence of CLI significantly increased with an increase in NLR. As an optimal cut-off a NLR of 3.95 was identified. Two groups were categorized, one containing 1441 patients (NLR≤3.95) and a second group with 680 patients (NLR>3.95). CLI was more frequent in NLR>3.95 patients (330(48.5%)) compared to NLR≤3.95 patients (350(24.3%)) (p<0.001), as were prior myocardial infarction (48(7.0%) vs. 47(3.3%), p<0.001) and stroke (73(10.7) vs. 98(6.8%), p<0.001). Regarding other inflammatory parameters, C-reactive protein (median 5.6 mg/l (2.3–19.1) vs. median 3 mg/l (1.5–5.5)) and fibrinogen (median 412 mg/dl (345.5–507.5) vs. 344 mg/dl (308–403.5)) also significantly differed in the two patient groups (both p<0.001). A NLR>3.95 was associated with an OR of 2.5 (95%CI 2.3–2.7) for CLI even after adjustment for other vascular risk factors. CONCLUSIONS: An increased NLR is significantly associated with patients at high risk for CLI and other vascular endpoints. The NLR is an easy to perform test, which could be used to highlight patients at high risk for vascular endpoints.