title: Validation of the atherosclerotic cardiovascular disease Pooled Cohort risk equations.
abstract: OBJECTIVE
  The American College of Cardiology/American Heart Association (ACC/AHA) Pooled Cohort risk equations were developed to estimate atherosclerotic cardiovascular disease (CVD) risk and guide statin initiation.
  
  
  OBJECTIVE
  To assess calibration and discrimination of the Pooled Cohort risk equations in a contemporary US population.
  
  
  METHODS
  Adults aged 45 to 79 years enrolled in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study between January 2003 and October 2007 and followed up through December 2010. We studied participants for whom atherosclerotic CVD risk may trigger a discussion of statin initiation (those without clinical atherosclerotic CVD or diabetes, low-density lipoprotein cholesterol level between 70 and 189 mg/dL, and not taking statins; n = 10,997).
  
  
  METHODS
  Predicted risk and observed adjudicated atherosclerotic CVD incidence (nonfatal myocardial infarction, coronary heart disease [CHD] death, nonfatal or fatal stroke) at 5 years because REGARDS participants have not been followed up for 10 years. Additional analyses, limited to Medicare beneficiaries (n = 3333), added atherosclerotic CVD events identified in Medicare claims data.
  
  
  RESULTS
  There were 338 adjudicated events (192 CHD events, 146 strokes). The observed and predicted 5-year atherosclerotic CVD incidence per 1000 person-years for participants with a 10-year predicted atherosclerotic CVD risk of less than 5% was 1.9 (95% CI, 1.3-2.7) and 1.9, respectively, risk of 5% to less than 7.5% was 4.8 (95% CI, 3.4-6.7) and 4.8, risk of 7.5% to less than 10% was 6.1 (95% CI, 4.4-8.6) and 6.9, and risk of 10% or greater was 12.0 (95% CI, 10.6-13.6) and 15.1 (Hosmer-Lemeshow χ2 = 19.9, P = .01). The C index was 0.72 (95% CI, 0.70-0.75). There were 234 atherosclerotic CVD events (120 CHD events, 114 strokes) among Medicare-linked participants and the observed and predicted 5-year atherosclerotic CVD incidence per 1000 person-years for participants with a predicted risk of less than 7.5% was 5.3 (95% CI, 2.8-10.1) and 4.0, respectively, risk of 7.5% to less than 10% was 7.9 (95% CI, 4.6-13.5) and 6.4, and risk of 10% or greater was 17.4 (95% CI, 15.3-19.8) and 16.4 (Hosmer-Lemeshow χ2 = 5.4, P = .71). The C index was 0.67 (95% CI, 0.64-0.71).
  
  
  CONCLUSIONS
  In this cohort of US adults for whom statin initiation is considered based on the ACC/AHA Pooled Cohort risk equations, observed and predicted 5-year atherosclerotic CVD risks were similar, indicating that these risk equations were well calibrated in the population for which they were designed to be used, and demonstrated moderate to good discrimination.
authors.affiliation: Department of Epidemiology, University of Alabama at Birmingham2Department of Medicine, University of Alabama at Birmingham.
authors.forename: Paul
authors.initials: P
authors.lastname: Muntner
authors.affiliation: Department of Epidemiology, University of Alabama at Birmingham.
authors.forename: Lisandro D
authors.initials: LD
authors.lastname: Colantonio
authors.affiliation: Department of Medicine, University of Vermont, Burlington.
authors.forename: Mary
authors.initials: M
authors.lastname: Cushman
authors.affiliation: Department of Epidemiology, Colorado School of Public Health, Aurora.
authors.forename: David C
authors.initials: DC
authors.lastname: Goff
authors.affiliation: Department of Biostatistics, University of Alabama at Birmingham.
authors.forename: George
authors.initials: G
authors.lastname: Howard
authors.affiliation: Department of Epidemiology, University of Alabama at Birmingham.
authors.forename: Virginia J
authors.initials: VJ
authors.lastname: Howard
authors.affiliation: Department of Neurology and Rehabilitation Medicine, University of Cincinnati, Cincinnati, Ohio.
authors.forename: Brett
authors.initials: B
authors.lastname: Kissela
authors.affiliation: Department of Epidemiology, University of Alabama at Birmingham.
authors.forename: Emily B
authors.initials: EB
authors.lastname: Levitan
authors.affiliation: Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Lloyd-Jones
authors.affiliation: Department of Medicine, University of Alabama at Birmingham.
authors.forename: Monika M
authors.initials: MM
authors.lastname: Safford
mesh_terms: D000368:Aged; D050197:Atherosclerosis / Q000453:epidemiology*; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D006949:Hyperlipidemias / Q000188:drug therapy; D015994:Incidence; D007407:Interviews as Topic; D008297:Male; D055641:Mathematical Concepts; D008875:Middle Aged; D012306:Risk; D018570:Risk Assessment / Q000379:methods*; D014481:United States / Q000453:epidemiology
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors