title: Association of standard clinical and laboratory variables with red blood cell distribution width.
abstract: BACKGROUND
  Red blood cell distribution width (RDW) strongly predicts clinical outcomes among patients with coronary disease and heart failure. The factors underpinning this association are unknown.
  
  
  METHODS
  In 6,447 individuals enrolled in the Measurement to Understand the Reclassification of Disease of Cabarrus/Kannapolis (MURDOCK) Study who had undergone coronary angiography between 2001 and 2007, we used Cox proportional hazards modeling to examine the adjusted association between RDW and death, and death or myocardial infarction (MI). Multiple linear regression using the R(2) model selection method was then used to identify clinical factors associated with variation in RDW.
  
  
  RESULTS
  Median follow-up was 4.2 (interquartile range 2.3-5.9) years, and the median RDW was 13.5% (interquartile range 12.9%-14.3%, clinical laboratory reference range 11.5%-14.5%). Red blood cell distribution width was independently associated with death (adjusted hazard ratio 1.13 per 1% increase in RDW, 95% CI 1.09-1.17), and death or MI (adjusted hazard ratio 1.12, 95% CI 1.08-1.16). Twenty-seven clinical characteristics and laboratory measures were assessed in the multivariable linear regression model; a final model containing 18 variables explained only 21% of the variation in RDW.
  
  
  CONCLUSIONS
  Although strongly associated with death and death or MI, only one-fifth of the variation in RDW was explained by routinely assessed clinical characteristics and laboratory measures. Understanding the latent factors that explain variation in RDW may provide insight into its strong association with risk and identify novel targets to mitigate that risk.
authors.affiliation: Duke Clinical Research Institute, Duke University Medical Center, Durham, NC.
authors.forename: Patrícia O
authors.initials: PO
authors.lastname: Guimarães
authors.affiliation: Duke Clinical Research Institute, Duke University Medical Center, Durham, NC.
authors.forename: Jie-Lena
authors.initials: JL
authors.lastname: Sun
authors.affiliation: Duke Clinical Research Institute, Duke University Medical Center, Durham, NC.
authors.forename: Kristian
authors.initials: K
authors.lastname: Kragholm
authors.affiliation: Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC; Duke Division of Cardiology, Duke University Medical Center, Durham, NC.
authors.forename: Svati H
authors.initials: SH
authors.lastname: Shah
authors.affiliation: Duke Clinical Research Institute, Duke University Medical Center, Durham, NC.
authors.forename: Karen S
authors.initials: KS
authors.lastname: Pieper
authors.affiliation: Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC; Duke Division of Cardiology, Duke University Medical Center, Durham, NC.
authors.forename: William E
authors.initials: WE
authors.lastname: Kraus
authors.affiliation: Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC; Duke Division of Cardiology, Duke University Medical Center, Durham, NC.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Hauser
authors.affiliation: Duke Clinical Research Institute, Duke University Medical Center, Durham, NC; Duke Division of Cardiology, Duke University Medical Center, Durham, NC.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Granger
authors.affiliation: Duke Clinical Research Institute, Duke University Medical Center, Durham, NC; Duke Division of Cardiology, Duke University Medical Center, Durham, NC. Electronic address: kristin.newby@duke.edu.
authors.forename: L Kristin
authors.initials: LK
authors.lastname: Newby
mesh_terms: D004909:Erythrocyte Indices / Q000502:physiology*; D004912:Erythrocytes / Q000166:cytology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000401:mortality; D009657:North Carolina / Q000453:epidemiology; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013997:Time Factors