BACKGROUND: Red blood cell distribution width (RDW) has been shown to predict clinical outcomes in cardiovascular diseases. We studied whether RDW is useful to predict early mortality in patients with acute dyspnea at an emergency department (ED).
METHODS: We retrospectively analyzed 907 patients with acute dyspnea who visited the ED from January 2009 to May 2009. Primary outcome was 30-day mortality.
RESULTS: Acute decompensated heart failure (29.9%) was the most common adjudicated discharge diagnosis followed by cancer (14.8%) and pneumonia (12.5%). There was a stepwise increase of 30-day mortality risk from lowest (RDW<12.9%) to highest (RDW>14.3%) RDW tertiles (1.4% vs. 8.3% vs. 18.3%; log-rank P<0.001). In multivariate Cox hazard analysis, RDW was an independent predictor of 30-day mortality after adjusting for other risk factors (HR 1.23; 95% CI 1.11-1.36; P<0.001). Adding RDW to conventional clinical predictors significantly improved prediction for 30-day mortality as measured by the area under the ROC curve (AUC, from 0.873 to 0.885; P=0.023) and the net reclassification improvement (NRI=14.1%; P<0.001)/integrated discrimination improvement (IDI=0.038; P=0.006).
CONCLUSIONS: Our findings suggest that RDW measured at ED is an independent and additive predictor of early mortality in patients with acute dyspnea.