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Usefulness of Red Cell Distribution Width as a Prognostic Marker in Pulmonary Hypertension

https://doi.org/10.1016/j.amjcard.2009.05.016Get rights and content

Red blood cell distribution width (RDW), a widely available biomarker, independently predicts adverse outcomes in left-sided heart failure. The relation between RDW and death in pulmonary hypertension (PH) is unknown. In a prospective study of 162 consecutive patients with PH, RDW was recorded during initial diagnostic right-sided cardiac catheterization, and patients were followed for 2.1 ± 0.8 years to determine vital status. Demographic, clinical, laboratory, and hemodynamic variables were compared by tertile of RDW. Cox proportional-hazards models were used to determine whether RDW was independently associated with death, and the prognostic utility of RDW was compared to that of other laboratory predictors, including N-terminal–pro–B-type natriuretic peptide (NT–pro-BNP). Of the 162 study patients, 78% were women, and 62% had pulmonary arterial hypertension. The mean age was 53 ± 15 years, and most patients had severe PH (mean pulmonary artery pressure 48 ± 13 mm Hg). The highest tertile of RDW predicted death (univariate hazard ratio 4.86, 95% confidence interval 1.37 to 17.29, p = 0.015; multivariate hazard ratio 2.4, 95% confidence interval 1.02 to 5.84, p = 0.045, after adjusting for age, gender, diabetes mellitus, connective tissue disease, diuretic use, phosphodiesterase inhibitor use, hemoglobin, mean corpuscular volume, and blood urea nitrogen [BUN]). Of the laboratory data, only RDW, BUN, and NT–pro-BNP were associated with death on univariate analysis. When RDW, BUN, and NT–pro-BNP were entered into a multivariate model, only RDW was still associated with death (p = 0.037 for RDW, p = 0.18 for BUN, and p = 0.39 for NT–pro-BNP). Adding NT–pro-BNP to RDW did not improve the prediction of mortality. In conclusion, RDW is independently associated with death in patients with PH and performs better as a prognostic indicator than NT–pro-BNP.

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Methods

We studied patients in the Pulmonary Hypertension Connection (PHC) registry, which was initiated in March 2004 and has been described in detail previously.6 For the purposes of the present study, we evaluated only patients entered into the PHC registry prospectively (all patients were evaluated at the University of Chicago Medical Center).

In the PHC registry, only 2 investigators with expertise in data management and understanding of clinical care of patients with PH entered the data. Neither

Results

Of the 162 study patients, 78% were women, and 62% had World Health Organization category I PH (pulmonary arterial hypertension). The mean age was 53 ± 15 years. Overall, patients in the study cohort had severe PH (right atrial pressure 11 ± 7 mm Hg, mean pulmonary artery pressure 48 ± 13 mm Hg, cardiac index 2.5 ± 1.0 L/min/m2, and pulmonary vascular resistance 9.6 ± 6.2 Wood units) and poor functional status (87% had World Health Organization functional class III or IV symptoms). The mean RDW

Discussion

In a prospective study of 162 patients, we found that increased RDW was independently associated with increased mortality in PH. Our results in patients with PH and right-sided heart failure are complementary to recent data that have demonstrated the prognostic utility of RDW in chronic left-sided heart failure, in patients with coronary artery disease, and in unselected patients who undergo coronary angiography.4, 5, 8 Unlike these other studies, RDW values in our study were higher (highest

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Conflicts of interest: Dr. Gomberg-Maitland has received research grant support from Actelion Pharmaceuticals Ltd., Allschwil, Switzerland; CoTherix, Inc., South San Francisco, California; Encysive Pharmaceuticals Inc., Houston, Texas; Gilead Sciences Inc., Foster City, California; Eli Lilly/ICOS, Indianapolis, Indiana; Pfizer Inc., New York, New York; and United Therapeutics, Silver Spring, Maryland. Dr. Gomberg-Maitland has served as a consultant and/or on advisory boards for Encysive Pharmaceuticals Inc., Gilead Sciences Inc., Pfizer Inc., and United Therapeutics. Dr. Shah has received research grant support from Actelion Pharmaceuticals Ltd. (Entelligence Young Investigator Award) and is also the recipient of a Scientist Development Grant from the American Heart Association, Dallas, Texas.

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