Prognostic value of neutrophil-to-lymphocyte ratio in acute coronary syndrome patients: a meta-analysis of hazard ratios

Background: Previous meta- analyses have revealed the prognostic significance of neutrophil- lymphocyte ratio (NLR) in acute coronary syndrome (ACS) by combining the odds ratios (ORs) or risk ratio (RRs). This study aims to supplement the previous meta-analysis by including only adjusted hazard ratios (HRs). We have investigated the value of NLR in predicting mortality and major adverse cardiovascular events (MACEs) in ACS patients. Methods: Relevant articles published were systematically searched from PubMed, the Cochrane Library, EMBASE and Web of before May 18, 2019. HRs with associated 95% confidence intervals (CIs) were calculated to estimate the effects. Results: A total of 8 articles of 4877 patients were included in the meta- analysis. Our analysis for patients with recent ACS indicated that higher NLR was a prognostic marker in predicting long- term mortality (HR=1.19, 95% CI=1.03-1.39 P=0.022), long-term MACEs (HR=1.41, 95% CI= 0.81-2.46, P=0.222), in- hospital mortality (HR=1.27, 95% CI= 1.15-1.40, P<0.001). Pretreatment NLR predicted long-term mortality/ MACEs in ACS patients (HR=1.17, 95% CI=1.07- 1.28, P<0.001). Conclusion: In conclusion, the updated meta- analysis of pooled adjusted HRs provided evidence that ACS patients with higher preconditioning NLR value have a higher risk of mortality.