adding CAC to cardiovascular risk factors resulted in an optimism-corrected incease in the c-statistic by 0.030(95% CI: 0.001 to 0.050) to 0.734(95% CI: 0.698 to 0.770) and substantially improved the risk classification of subjects by 0.030(95% CI: 0.001 to 0.050) to 0.734 (95% CI: 0.698 to 0.770) and substantially improved the risk classification of subjects (continuous net reclassification index = 34.0%)