Table 4.

Estimated prevalence of a coronary artery calcium score in each of four standard categories, depending on the Framingham estimated 10-year risk of coronary heart disease events.

Framingham 10-year CHD risk estimate*	Estimated prevalence of a CAC score in the given range†, %
	0	1–100	101–400	>400
2.5%	75	19	4	1
5.0%	68	23	6	2
7.5%	61	28	8	3
10.0%	52	32	11	5
12.5%	44	36	13	7
15.0%	36	38	17	9
17.5%	29	40	19	12
20.0%	22	41	22	15
22.5%	17	40	25	18
25.0%	13	39	27	22

* – 10-year risk of CHD events estimated according to equations derived from the Framingham study[16]. For assumptions, see Methods.

† – Proportions of subjects in each given CAC score category were estimated by a two step process: 1) Logistic regression to predict the presence of CAC according to estimated 10-year risk (see Table 2 for model coefficients), and 2) Linear regression to predict the extent of CAC, as measured by the natural log-transformed CAC score (see Table 3 for model coefficients). Other values required for this calculation were the logistic regression constant (-1.44), the linear regression constant (3.17), and the standard deviation of the residuals after linear regression (1.707).

CAC – Coronary artery calcium; CHD – Coronary heart disease.