Racial differences in the neutrophil-to-lymphocyte ratio in patients with non-ST-segment elevation myocardial infarction

Objectives The neutrophil-to-lymphocyte ratio (NLR) predicts short-term and long-term mortalities in patients with stable and unstable coronary artery disease. However, it has been reported that white blood cell and neutrophil counts vary considerably among different races. We aimed to assess the impact of racial difference on NLR in our diverse population with non-ST-segment elevation myocardial infarction (NSTEMI). Methods We carried out a retrospective analysis of 456 consecutive NSTEMI patients who had undergone coronary angiography. The patients were divided into four groups on the basis of self-reported race: White, Hispanic, African-American, and Asian. NLR was compared among the four groups. Univariate and multivariate linear regression analyses were carried out between NLR and baseline clinical characteristics and angiographic findings. The primary outcome was inhospital mortality. Results The median NLR in the entire study population was 3.47 (interquartile range, 2.16-5.57). NLR differed significantly among the four groups according to the Kruskal-Wallis test (P=0.03). NLR was significantly lower in the African-American group compared with the White group according to the Steel-Dwass test (P=0.03). Multivariate analysis revealed that African-American ethnicity was negatively associated with NLR (P=0.04). The second multivariate analysis using the White group as a reference also revealed that African-American ethnicity was negatively associated with NLR (P=0.04). There was no significant difference in inhospital mortality among the four groups. Conclusion The present study demonstrated an independent association between race and NLR in patients with NSTEMI, suggesting that a tailored cutoff value according to race would provide more precise prognostic information.