Red Blood Cell Distribution and Survival in Patients with Chronic Obstructive Pulmonary Disease

Abstract

Background: Cardiovascular disease (CVD) contributes significantly to mortality in chronic obstructive pulmonary disease (COPD). Red blood cell distribution width (RDW), an automated measure of red blood cell size heterogeneity that is largely overlooked, is a newly recognized mortality marker in patients with established CVD. It is unknown whether RDW is associated with mortality in COPD patients. Aims: To study the prognostic value of RDW in patients with COPD and to compare the value of this measurement with cardiac, respiratory, and hemotological status. Method: We performed retrospective analyses of 270 patients stable with COPD who were admitted to our hospital between January 2007 and December 2009. Demographic, clinical, echocardiographic, and laboratory characteristics were registered and recorded COPD deaths were registered as outcomes. Results: In the overall patients, the RDW level had a mean value of 15.1 +/- 2.4. RDW was positively correlated with C-reactive protein (CRP) (p = 0.008, r = 0.21), right ventricular dysfunction (RVD) (p < 0.001, r = 0.25), and pulmonary arterial hypertension (PAH) (p = 0.03, r = 0.14). Variables (p < 0.1) included in the univariate survival analysis were forced expiratory volume in 1 second (FEV1% predicted), RDW levels, age, PaCO2, albumine and CRP levels, presence of CVD, presence of anemia, presence of RVD, and presence of PAH. Subsequent multivariate analysis suggested that RDW levels (1.12; 95% CI, 1.01 to 1.24; p = 0.01), and presence of RVD (2.6; 95% CI, 1.19 to 5.8; p = 0.01) were independently related to mortality. Conclusion: Elevated RDW levels were associated with increased mortality risk in stable COPD patients.