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RBC distribution width may predict stroke death.

NEW ORLEANS -- Red blood cell distribution width appears to be a significant predictor of stroke mortality, according to data obtained from the third National Health and Nutrition Examination Survey.

An analysis of data from 480 participants in NHANES III who had a stroke and who were aged older than 24 years showed a statistically significant difference in mean red blood cell distribution width (RDW) between the participants who survived stroke and those who did not.
Characteristics Associated With Stroke Mortality

 Adjusted Hazard Ratio

Age older than 64 years 4.73

RDW [greater than or equal to] 13.9% vs. 2.00
RDW [less than or equal to] 12.75%

Current smoker 2.00

Diabetes 1.93

History of MI 1.80

Male 1.61

Higher white blood cell count 1.08


Lower hematocrit 0.95

Note: Based on NHANES III data for 480 stroke patients older than 24
years of age.

Sources: Dr. Ani and Dr. Obviagele


Several factors, including red blood cell distribution width at the 75 percentile or greater, were associated with a significantly increased relative risk of mortality in the stroke patients. (See box.)

The findings were from both univariate and multivariate analyses and were adjusted for known cardiovascular, hematologic, lifestyle, and sociodemographic variables.

When the participants were categorized into quartiles based on their RDW levels (0%-12.75% reference group; greater than 12.75% through 13.3%; greater than 3.3% through 13.9%; and greater than 13.9%), those who had levels of 13.9% and greater had a twofold increased relative risk of death, compared with those who were in the reference group, Dr. Chizobam Ani and Dr. Bruce Obviagele of Charles Drew University of Medicine and Science, Lynwood, Calif., and their colleagues reported in a poster at a meeting that was sponsored by the International Society on Hypertension in Blacks.

The findings are of particular interest because RDW is a measure of the variation of red blood cell volume and is routinely reported as part of standard complete blood count measures.

Higher values indicate greater variation in size and morphology of the red cells.

Previous studies have demonstrated that RDW is a strong independent predictor of morbidity and mortality in patients with myocardial infarction, heart failure, or end-stage renal disease.

The findings of the current analysis suggest that red blood cell distribution width may be a useful prognostic tool in stroke patients as well, the investigators concluded.

This study was based on nationally representative data from patients who were followed from baseline between 1988 and 1994 until mortality assessment in 2000.

Among the possible explanations for the association between red blood cell distribution width and stroke mortality seen in this study are rapid red blood cell demise occurring in the context of an underlying inflammatory state or underlying hemopoietic pathologies secondary to nutritional deficiency that may lead to worse cardiovascular outcomes.

A mechanistic or hemorheologic role of red cell size variations on deformability and embolic phenomenon is another possible explanation, the researchers wrote.

They noted that additional longitudinal studies to further explore these relationships and potential explanations are warranted.

BY SHARON WORCESTER

Southeast Bureau
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Title Annotation:Neurology; Red blood cell
Author:Worcester, Sharon
Publication:Internal Medicine News
Geographic Code:1USA
Date:Oct 15, 2008
Words:521
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