Neutrophil to lymphocyte ratio in relation to risk of all-cause mortality and cardiovascular events among patients undergoing angiography or cardiac revascularization: a meta-analysis of observational studies

Abstract

Objective: The aim of this study was to investigate whether neutrophil to lymphocyte ratio (NLR) was an independent predictor for all-cause mortality or cardiovascular events in patients undergoing angiography or cardiac revascularization with observational studies by meta-analysis.

Methods: Pubmed and Embase were searched without language restrictions for cohort studies published prior to November 2013. Citations were independently screened by 2 authors, and those meeting the inclusion criteria defined a priori were retained. Data on authors, year of publication, location, target participant, comparison of NLR, outcome assessment, number of event and sample size, duration and statistical adjustments were abstracted.

Results: Eight studies were identified that reported on all-cause mortality and five studies were identified that reported on cardiovascular events. The pooled relative risk (RR) of all-cause mortality was 2.33 (95% CI 1.88-2.88) and the RR of cardiovascular events was 1.89 (95% CI 1.42, 2.52) comparing the highest with the lowest category of NLR.

Conclusions: The meta-analysis indicates that NLR is a predictor of all-cause mortality and cardiovascular events. Further well-designed trials are warranted to confirm this association.

Keywords: All-cause mortality; Cardiovascular events; Meta-analysis; Neutrophil/lymphocyte ratio.