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Red blood cell measure linked to stroke death.

NEW ORLEANS -- Red blood cell distribution width appears to be a significant predictor of stroke mortality, according to data 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 those who survived stroke and those who did not.

Several factors, including red blood cell distribution width at the 75th percentile or greater, were associated with a significantly increased relative risk of mortality (see graphic), according to findings from both univariate and multivariate analyses (with adjustments for known cardiovascular, hematologic, lifestyle, and sociodemographic variables).

When participants were categorized into quartiles based on 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 with levels of 13.9% and greater had a twofold increased relative risk of death, compared with those 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 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, and end-stage renal disease. The findings of the current analysis suggest red blood cell distribution width may be a useful prognostic tool in stroke patients, they concluded.

Among the possible explanations for the association between red blood cell distribution width and stroke mortality seen in this study, which was based on nationally representative data from patients followed from baseline between 1988 and 1994 until mortality assessment in 2000, are rapid red blood cell demise occurring in the context of an underlying inflammatory state, underlying hematopoietic pathologies secondary to nutritional deficiency that may lead to worse cardiovascular outcomes, and a mechanistic or hemorheologic role of red cell size variations on deformability and embolic phenomenon, the researchers wrote. They noted that additional longitudinal studies to further explore these relationships and potential explanations are warranted.

BY SHARON WORCESTER

Southeast Bureau
Characteristics Associated With Stroke Mortality

                                             Adjusted
                                           Hazard Ratio

Age older than 64 years                        4.73
RDW [greater than or equal to] 13.9%
  vs. RDW [less than or equal to] 12.75%       2.00
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
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Title Annotation:Clinical Rounds
Author:Worcester, Sharon
Publication:Family Practice News
Geographic Code:1USA
Date:Oct 1, 2008
Words:496
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