title: Prognostic value of cardiac risk factors and coronary artery calcium screening for all-cause mortality.
abstract: OBJECTIVE
  To develop risk-adjusted multivariable models that included risk factors and coronary calcium scores determined with electron-beam computed tomography (CT) in asymptomatic patients for the prediction of all-cause mortality.
  
  
  METHODS
  We followed up a cohort of 10,377 asymptomatic individuals undergoing cardiac risk factor evaluation and coronary calcium screening with electron-beam CT. Multivariable Cox proportional hazards models were developed to predict all-cause mortality. Risk-adjusted models incorporated traditional risk factors for coronary disease and coronary calcium scores.
  
  
  RESULTS
  Cardiac risk factors such as family history of coronary disease (69%), hypercholesterolemia (62%), hypertension (44%), smoking (40%), and diabetes (9%) were prevalent. The frequency of coronary calcium scores was 57%, 20%, 14%, 6%, and 3% for scores of 10 or less, 11-100, 101-400, 401-1,000, and greater than 1,000, respectively. During a mean follow-up of 5.0 years +/- 0.0086 (standard error of the mean), the death rate was 2.4%. In a risk-adjusted model (model chi2 = 388.2, P <.001), coronary calcium was an independent predictor of mortality (P <.001). Risk-adjusted relative risk values for coronary calcium were 1.64, 1.74, 2.54, and 4.03 for scores of 11-100, 101-400, 401-1,000, and greater than 1,000, respectively (P <.001 for all values), as compared with that for a score of 10 or less. Five-year risk-adjusted survival was 99.0% for a calcium score of 10 or less and 95.0% for a score of greater than 1,000 (P <.001). With a receiver operating characteristic curve, the concordance index increased from 0.72 for cardiac risk factors alone to 0.78 (P <.001) when the calcium score was added to a multivariable model for prediction of death.
  
  
  CONCLUSIONS
  This large observational data series shows that coronary calcium provides independent incremental information in addition to traditional risk factors in the prediction of all-cause mortality.
authors.affiliation: American Cardiovascular Research Institute, Atlanta, GA, USA.
authors.forename: Leslee J
authors.initials: LJ
authors.lastname: Shaw
authors.forename: Paolo
authors.initials: P
authors.lastname: Raggi
authors.forename: Enrique
authors.initials: E
authors.lastname: Schisterman
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
authors.forename: Tracy Q
authors.initials: TQ
authors.lastname: Callister
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000032:analysis*; D003331:Coronary Vessels / Q000737:chemistry*; D005260:Female; D005500:Follow-Up Studies; D006331:Heart Diseases; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality; D011379:Prognosis; D016016:Proportional Hazards Models; D012307:Risk Factors; D014057:Tomography, X-Ray Computed
chemical_list: D002118:Calcium