Abstract 12768: The Red Cell Distribution Width Standard Deviation (RDW-SD) More Strongly Predicts Mortality than the RDW
Background: The red cell distribution width (RDW) predicts mortality, including among cardiovascular, pulmonary, trauma, and other patients, and in the general population. RDW is the standard deviation (SD) of the red cell volume divided by the mean corpuscular volume (MCV). Because higher MCV also predicts mortality risk, we hypothesized that RDW-SD (the RDW numerator) predicts mortality more strongly than RDW.
Methods: RDW, MCV, and other complete blood count (CBC) and basic metabolic profile (BMP) laboratory parameters were measured on N=119,530 adult patients seen at Intermountain Healthcare hospitals for any inpatient, outpatient, or emergency department diagnosis. RDW-SD was calculated as RDW times MCV. All-cause mortality was determined from hospital records, Utah death certificates, and the Social Security death master file and associations tested using Cox regression.
Results: Patients averaged 55.5±20.0 years of age and 58.3% were female. In univariable analysis, RDW-SD was more strongly associated with mortality than RDW (Table). This difference remained after adjustment for age, sex, and BMP and CBC factors except the MCV. For quintile 5 vs. 1, univariable and adjusted RDW-SD hazard ratios were significantly higher than corresponding RDW hazard ratios (p≤0.05). When adjusted for MCV, the RDW association strengthened to a similar magnitude as RDW-SD.
Conclusions: In a large general patient population, RDW-SD predicted mortality more strongly than RDW in univariable and with multivariable adjustment excluding MCV. Adjustment for MCV removed this difference in predictive ability. This suggests that the use of RDW as a risk predictor requires concurrent consideration of other CBC parameters. Importantly, some clinical hematology analyzers now provide RDW-SD with the CBC.
- © 2013 by American Heart Association, Inc.