Incremental Predictive Value of Red Cell Distribution Width for 12-Month Clinical Outcome After Acute Myocardial Infarction

Background: The incremental predictive value of red cell distribution width (RDW) for major adverse cardiac events (MACEs) has not been fully investigated in patients with acute myocardial infarction (AMI). Hypothesis: The aim of this study was to determine the incremental value of RDW to the established risk factors in predicting clinical outcomes after AMI. Methods: Between November 2005 and January 2010, 1596 patients with AMI (1070 male; mean age, 64.5 +/- 11.9 years) were analyzed in this study. Baseline levels of RDW were measured at the time of admission. The 12-month MACEs were defined as death and nonfatal MI. Results: The RDW levels were significantly higher in patients with 12-month MACEs (13.8 +/- 1.3% vs 13.3 +/- 1.2%, P<0.001). In a Cox proportional hazards model, RDW (hazard ratio [HR]: 1.19, P=0.016) was an independent predictor for 12-month MACEs. Adding RDW to established risk factors and hemoglobin levels significantly improved prediction for 12-month MACEs, as shown by the net reclassification improvement (0.297; P=0.012) and integrated discrimination improvement (0.0143; P=0.042). The likelihood ratio test showed that RDW added incremental predictive value to the combination of hemoglobin and established risk factors (P=0.005). Patients were categorized into 4 groups according to quartiles of RDW at baseline. Adjusted HRs for 12-month MACEs were 1 (RDW <= 12.6%, reference), 4.24 (RDW 12.7%-13.1%, P=0.01), 4.36 (RDW 13.2%-13.9%, P=0.008), and 6.18 (RDW 13.2%-13.9%, P=0.001), respectively. Conclusions: In post-myocardial infarction patients, baseline RDW levels at admission could provide incremental predictive value to established risk factors for predicting 12-month MACEs.