title: Sex and Race-Ethnicity Secular Trends in Mean and Elevated Red Blood Cell Distribution Width Among Adults in the United States, 1999-2012.
abstract: OBJECTIVE
  Red blood cell distribution width (RDW) has been shown to associate with increased risk of cardiovascular and non-cardiovascular death. To our knowledge, no study has examined secular trends in RDW over the last decade.
  
  
  METHODS
  Serial cross-sectional design.
  
  
  METHODS
  Data from the National Health and Nutrition Examination Survey (NHANES), 1999-2012, were used.
  
  
  METHODS
  34,171 adults.
  
  
  METHODS
  RDW was assessed from a blood sample derived from the coefficient of variation of the red cell volume distribution histogram and reported as a percent. Elevated RDW was defined as an RDW > 14.6%.
  
  
  RESULTS
  The overall age-adjusted mean RDW increased progressively and significantly (P<.05) from 12.59% in 1999-2000 to 12.89% in 2011-2012. The overall age-adjusted prevalence of elevated RDW increased progressively and significantly (P<.05) from 4.01% in 1999-2000 to 6.25% in 2011-2012. Statistically significant increases over this time period also occurred among non-Hispanic White women, non-Hispanic Black men and women, and Mexican American men and women. Across all sex and race-ethnicity combinations, women, compared with men, had higher RDW and larger increases over time in mean and elevated RDW.
  
  
  CONCLUSIONS
  Mean and elevated RDW has progressively increased from 1999-2012 among adults in the United States, with increases observed among non-Hispanic Whites, Blacks, and Mexican Americans. Future research is needed to describe the determinants and implications of this RDW rise, as well as explanations for why a greater RDW change has occurred among women.
authors: Center for Health Behavior Research, Department of Health, Exercise Science, and Recreation Management, The University of Mississippi.
authors: Paul D
authors: PD
authors: Loprinzi
authors: Kevser Ermin Applied Physiology Laboratory, Department of Health, Exercise Science, and Recreation Management, The University of Mississippi.
authors: Jeremy P
authors: JP
authors: Loenneke
authors: Ciccarone Center for the Prevention of Heart Disease, Johns Hopkins Hospital, Baltimore, MD.
authors: Haitham M
authors: HM
authors: Ahmed
authors: Ciccarone Center for the Prevention of Heart Disease, Johns Hopkins Hospital, Baltimore, MD.
authors: Michael J
authors: MJ
authors: Blaha
mesh_terms: D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D000368:Aged; D002318:Cardiovascular Diseases / Q000097:blood* / Q000208:ethnology; D003430:Cross-Sectional Studies; D004912:Erythrocytes; D005260:Female; D006801:Humans; D008297:Male; D017058:Mexican Americans / Q000706:statistics & numerical data; D008875:Middle Aged; D009749:Nutrition Surveys; D015995:Prevalence; D014481:United States; D044465:White People / Q000706:statistics & numerical data
keywords: Cardiovascular Disease; Epidemiology; NHANES