Relationship between red cell distribution width (RDW) and clinical outcomes in non-ST elevation myocardial infarction and unstable angina pectoris: 3-years follow-up
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Objectives: Red cell distribution width (RDW), a marker of variation of the size of the circulating red blood cells, was evaluated in patients with non-ST elevation myocardial infarction (NSTEMI) and unstable angina pectoris (UAP). Background: Higher RDW is associated with mortality in patients with symptomatic cardiovascular disease, heart failure, and also in the general population. We hypothesized that admission RDW would be predictive of adverse clinical outcomes in NSTEMI and UAP. Methods: A total of 310 (mean age 59.28±11.93; 236 males, 74 females) patients with NSTEMI and UAP were prospectively enrolled into this study. Admission RDW was measured as part of the automated complete blood count. The study population was divided into tertiles based on admission RDW values. A high RDW (n=95) was defined as a value in the third tertile (>14%), and a low RDW (n=215) was defined as a value in the lower two tertiles (≤14%). Patients were followed for clinical outcomes for up to 3-years after discharge. Results: Kaplan-Meier survival analysis showed 3-years mortality rate of 19% in patients with high RDW versus 5.6% in low RDW group (p<0.001). In a receiver operating characteristic curve analysis, a RDW value of 14% identified as an effective cut-point in NSTEMI and UAP of 3-years cardiovascular mortality (area under curve=0.70, 95% confidence interval 0.62 to 0.79). A RDW value of >14% yielded a sensitivity of 60%, a specificity of 72.5%. We used Cox proportional hazard models to examine the association between RDW and adverse clinical outcomes. A significant association was noted between high admission RDW level and the adjusted risk of cardiovascular mortality (hazard ratio: 3.2, 95% confidence interval:1.3-7.78, p=0.01). There was a good correlation between RDW levels and age (r:0.246, p<0.001), TIMI risk score (r:0.277 p<0.001), and GRACE risk score (r:0.270, p<0.001). Conclusion: RDW is a readily available clinical laboratory value that is associated with long-term cardiovascular mortality in NSTEMI and UAP.