Relation between red blood cell distribution width (RDW) and all-cause mortality at two years in an unselected population referred for coronary angiography

Background: Red blood cell distribution width (RDW), a numerical measure of the variability in size of circulating erythrocytes, has recently been shown to be a strong predictor of adverse outcomes in patients with heart failure and in patients with prior myocardial infarction but no symptomatic heart failure at baseline, even after adjustment for hematocrit. However, there are no data in other cardiac populations, including patients with acute coronary syndromes (ACS). Methods: The present study investigated the long-term prognostic significance of baseline RDW in a well-characterized cohort of 389 male patients who were referred to coronary angiography for a variety of indications. All patients were followed prospectively for all-cause mortality, and data regarding this endpoint was available for 97% of the population at 24 months. Results: After controlling for a variety of baseline variables (including hemoglobin and the presence of heart failure), RDW (analyzed as a categorical variable comparing the upper tertile of baseline values to the lower two levels combined) was a strong and independent predictor of all-cause mortality using a Cox proportional hazards model [hazard ratio (HR) 2.69, 95% confidence interval (CI) 1.50-4.84, p = 0.0008]. In addition, baseline RDW was also an independent predictor of all-cause mortality in the non-anemic (HR 4.73, 95% CI 2.06-10.86, p = 0.0003) and ACS (HR 2.90, 95% CI 1.32-6.38, p = 0.0082) subpopulations of patients. Conclusions: These data demonstrate that elevated RDW is a strong and independent predictor of all-cause mortality in an unselected population of male patients across a broad spectrum of risk (including ACS) referred for coronary angiography.