title: Red cell distribution width, inflammatory markers and cardiorespiratory fitness: results from the National Health and Nutrition Examination Survey.
abstract: OBJECTIVE
  Cardiorespiratory fitness is an important predictor of cardiovascular morbidity and mortality. Both red cell distribution width (RDW) and inflammatory markers like C-reactive protein (CRP) have been shown to predict adverse outcomes in patients with heart disease.
  
  
  METHODS
  We utilized pooled data from NHANES 1999-2004 to assess cardiorespiratory fitness in healthy adults 12-49 years old using submaximal exercise. The primary outcome was the estimated maximal oxygen uptake (VO2max). Low fitness was defined as VO2max < 20th percentile of age- and gender-based reference category.
  
  
  RESULTS
  In our study, we estimated 21.2% of individuals had low fitness. Elevated RDW (>13%) was encountered in 20.4% subjects with low fitness as compared to 14.0% subjects in the control group (p < 0.001). Similarly, elevated CRP (>0.5 mg/dL) was found among 17.4% subjects with low fitness as compared to 12.4% subjects in the control group (p < 0.001). Adjusted analysis demonstrated a dose-response relationship between low cardiorespiratory fitness and increasing RDW or CRP.
  
  
  CONCLUSIONS
  In a large representative database of general US population, we observed a significant association between elevated RDW and elevated CRP with low cardiorespiratory fitness.
authors.affiliation: Cardiovascular Medicine, Cleveland Clinic, Cleveland, OH 44195, USA. dr.shikhar.agarwal@gmail.com
authors.forename: Shikhar
authors.initials: S
authors.lastname: Agarwal
mesh_terms: D000293:Adolescent; D000328:Adult; D002097:C-Reactive Protein / Q000032:analysis*; D002648:Child; D004909:Erythrocyte Indices; D017079:Exercise Tolerance / Q000502:physiology*; D006304:Health Status; D006331:Heart Diseases / Q000453:epidemiology*; D006801:Humans; D008875:Middle Aged; D009749:Nutrition Surveys; D016017:Odds Ratio; D010101:Oxygen Consumption; D012140:Respiratory Tract Diseases / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D002097:C-Reactive Protein