title: Red cell distribution width and risk of cardiovascular mortality: Insights from National Health and Nutrition Examination Survey (NHANES)-III.
abstract: BACKGROUND
  Red cell distribution width (RDW) has been linked to cardiovascular disease. We sought to determine whether addition of RDW improved the Framingham risk score (FRS) model to predict cardiovascular mortality in a healthy US cohort.
  
  
  METHODS
  We performed a post-hoc analysis of the National Health and Nutritional Examination Survey-III (1988-94) cohort, including non-anemic subjects aged 30-79years. Primary endpoint was death from coronary heart disease (CHD). We divided the cohort into three risk categories: <6%, 6-20% and >20%. RDW>14.5 was considered high. Kaplan-Meier survival curves and Cox proportional hazards models were created. Discrimination, calibration and reclassification were used to assess the value of addition of RDW to the FRS model.
  
  
  RESULTS
  We included 7005 subjects with a mean follow up of 14.1years. Overall, there were 233 (3.3%) CHD deaths; 27 (8.2%) in subjects with RDW>14.5 compared to 206 (3.1%) in subjects with RDW≤14.5 (p<0.001). Adjusted hazard ratio of RDW in predicting CHD mortality was 2.02 (1.04-3.94, p=0.039). Addition of RDW to FRS model showed significant improvement in C-statistic (0.8784 vs. 0.8751, p=0.032) and area under curve (0.8565 vs. 0.8544, p=0.05). There was significant reclassification of FRS with a net reclassification index (NRI) of 5.6% (p=0.017), and an intermediate-risk NRI of 9.6% (p=0.011). Absolute integrated discrimination index (IDI) was 0.004 (p=0.02), with relative IDI of 10.4%.
  
  
  CONCLUSIONS
  Our study demonstrates that RDW is a promising biomarker which improves prediction of cardiovascular mortality over and above traditional cardiovascular risk factors.
authors.affiliation: Department of Cardiology, Lehigh Valley Health Network, Allentown, PA, United States. Electronic address: neerajshah86@gmail.com.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Shah
authors.affiliation: Department of Internal Medicine, St. Joseph Hospital and Medical Center, Phoenix, AZ, United States.
authors.forename: Mohit
authors.initials: M
authors.lastname: Pahuja
authors.affiliation: Department of Cardiology, University of Louisville, Louisville, KY, United States.
authors.forename: Sadip
authors.initials: S
authors.lastname: Pant
authors.affiliation: Medical Student, Kasturba Medical College, India.
authors.forename: Aman
authors.initials: A
authors.lastname: Handa
authors.affiliation: Department of Cardiology, Staten Island University Hospital, Staten Island, NY.
authors.forename: Vratika
authors.initials: V
authors.lastname: Agarwal
authors.affiliation: Department of Cardiology, University of Miami, Miami, FL, United States.
authors.forename: Nileshkumar
authors.initials: N
authors.lastname: Patel
authors.affiliation: Department of Cardiology, Lehigh Valley Health Network, Allentown, PA, United States.
authors.forename: Raman
authors.initials: R
authors.lastname: Dusaj
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood* / Q000401:mortality; D004909:Erythrocyte Indices; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys / Q000379:methods*; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012372:ROC Curve; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
chemical_list: D015415:Biomarkers
keywords: Coronary heart disease; Framingham risk score; Red cell distribution width