The Neutrophil-Lymphocyte Ratio Predicts Mortality in Acute Coronary Syndrome (NLR-ACS): A Meta-analysis

Abstract

BACKGROUND: The neutrophil to lymphocyte ratio (NLR) is a recently described biomarker of inflammation that is an independent predictor of death and myocardial infarction. It integrates two leukocyte subtype counts with opposing actions in terms of vascular inflammation. This can be readily derived from a simple routine complete blood count taken during admission. We conducted a meta-analysis on the usefulness of a high NLR value in predicting mortality among patients with acute coronary syndrome (ACS). OBJECTIVE: To determine the association of neutrophil to lymphocyte ratio and mortality among patients with acute coronary syndrome. METHODS: We conducted a systematic search of studies using MEDLINE, EMBASE, ScienceDirect, and Cochrane Central Register of Controlled Trials databases and examined reference lists of studies that used the NLR in ACS patients in reporting mortality. We identified 12 studies that met inclusion criteria including 2 local studies. The study title, follow-up period, neutrophil-lymphocyte ratio, and mortality outcomes were extracted from these studies. Each study was assessed using the Newcastle-Ottawa Quality Assessment Scale. These were done independently by the authors resolving disagreements, if any, by discussion. The outcome of interest was assessed using Mantel Haenzel analysis to compute for odds ratio, and evaluation of heterogeneity were carried out using Review Manager (RevMan) 5.0.18 (The Nordic Cochrane Centre, The Cochrane Collaboration). RESULTS: Data were combined from 12 studies enrolling 9,835 patients. Pooled analysis showed that a high NLR was predictive of increased total mortality among patients presenting with ACS compared to those patients whose NLR were not high (8.65% vs 2.26%, OR 4.10, 95% CI 3.36, 5.00; p<0.00001). Data were homogenous (I2=0%) and there was no evidence of publication bias by funnel-plot method. Thirty-day mortality, including in-hospital death, was likewise increased among those with high NLR (7.78% vs 2.22%, OR 3.67, 95% CI 2.93, 4.58; p<0.00001; I2=0%). CONCLUSION: A high NLR value is associated with high mortality among patients with ACS. This parameter can be easily derived from a routine complete blood count taken during hospital admission and is a useful parameter to determine prognosis and may indicate a more intensive approach to therapy. Keywords: neutrophil-lymphocyte ratio, NLR, acute coronary syndrome, mortality, ACS, NSTEMI, STEMI, unstable angina, ST-segment myocardial infarction, non-ST-segment myocardial infarction