Coronary calcium does not accurately predict near-term future coronary events in high-risk adults

Background-Prognostic risk models have had limited success in predicting co ronary events in subjects with multiple risk factors. We and others have pr oposed an alternative approach using radiographically detectable coronary c alcium. We evaluated and compared the predictive value of these 2 approache s for determining coronary event risk in asymptomatic adults with multiple coronary risk factors, In addition, we assessed the predictive value of a r isk model that included calcium score and cardiac risk-factor data. Methods and Results-We recruited 1196 asymptomatic high-coronary-risk subje cts who then underwent risk-factor assessment and cardiac electron-beam CT (EBCT) scanning and were followed up for 41 months with a 99% success rate. We applied the Framingham model and our data-derived risk model to determi ne the 3-year likelihood of a coronary event. The mean age of our cohort wa s 66 years, and mean 3-year Framingham risk was 3.3+/-3.6%. Sixty-eight per cent (818 subjects) had detectable coronary calcium. There were 17 coronary deaths (1.4%) and 29 nonfatal infarctions (2.4%). The receiver operating c haracteristic (ROC) curve areas calculated from the Framingham model, our d ata-derived risk model, and the calcium score were 0.69+/-0.05, 0.68+/-0.05 , and 0.64+/-0.05, respectively (P=NS), When calcium score was included as a variable in the data-derived model, the ROC area did not change significa ntly (0.68+/-0.05 to 0.71+/-0.04; P=NS). Conclusions-Neither risk-factor assessment nor EBCT calcium is an accurate event predictor in high-risk asymptomatic adults, EBCT calcium score does n ot add significant incremental information to risk factors, and its use in clinical screening is not justified at this time.