Association between red blood cell distribution width and outcomes at six months in patients with acute coronary syndromes

Higher values of red ceildistribution width (RDW) may be associated with adverse outcomes in patients with heart failure and in those with stable coronary artery disease. We assessed the hypothesis that higher RDW values are associated with adverse cardiovascular outcomes in patients with acute coronary syndromes (ACS). We studied 1796 patients with ACS admitted to a coronary care unit. We analyzed clinical and laboratory characteristics, management, and outcomes of patients according to tertiles of baseline RDW. The primary outcome was death or myocardial infarction (MI) during six-month follow-up. Patients with higher RDW values tended to be older, were more likely to be female and have a history of MI, and more often had renal dysfunction, anemia, and Killip class >I on admission (p < 0.05). Higher RDW values were associated with increased 6-month mortality (tertile 1: 8.2%; tertile 2: 10.9%; tertile 3: 15.5%; p = 0.001 for trend) and increased 6-month death/MI rates (tertile 1, 13.0%; tertile 2, 17.2%; tertile 3, 22.9%; p < 0.0001 for trend). An association between higher RDW and increased 6-month death/MI rates was found in patients with non-ST-elevation ACS (10.5% vs. 15.3% vs. 22.7%; p < 0.001 for trend), with a tendency in patients admitted with ST-elevation MI (15.1% vs. 19.1% vs. 23.1%; p = 0.053 for trend). After adjustment for baseline characteristics and treatment, higher RDW values remained independently associated with the study's primary composite outcome but not with all-cause death. Using the first tertile of RDW as reference, the adjusted odds ratio (OR) for 6-month death/MI among patients in the highest RDW tertile was 1.43 (95% confidence interval [CI], 1.00-2.05; p = 0.049). Using RDW as a continuous variable, the adjusted OR for 6-month death/MI was 1.16 (95% CI, 1.03-1.30; p = 0.017) per 1% increase in RDW. RDW is an easily determined predictor of outcome after ACS. We found a graded independent association between higher RDW values and adverse outcomes in patients with ACS.