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Table 5 Examples of how to use the coronary artery calcium score to refine risk estimates.

From: What does my patient's coronary artery calcium score mean? Combining information from the coronary artery calcium score with information from conventional risk factors to estimate coronary heart disease risk

Clinical scenario Pre-test 10-year CHD risk estimate* CAC score category Proportion of CAC scores falling within the given category† Post-test 10-year risk estimate for each CAC score category‡
     Conservative§ Optimistic§
60-year-old woman with hypertension and high cholesterol 15% 0: 0.47 9% 6%
   1–100: 0.36 15% 13%
   101–400: 0.12 25% 31%
   >400: 0.05 34% 51%
50-year-old man without other CHD risk factors 6% 0: 0.59 4% 3%
   1–100: 0.31 7% 6%
   101–400: 0.07 11% 15%
   >400: 0.03 16% 27%
40-year-old woman who smokes 3% 0: 0.89 2% 2%
   1–100: 0.10 4% 5%
   101–400: 0.01 7% 12%
   >400: 0.00 10% 22%
80-year-old man with high cholesterol 26% 0: 0.05 9% 5%
   1–100: 0.25 15% 10%
   101–400: 0.30 26% 23%
   >400: 0.40 35% 39%
  1. * – From published Framingham equations [16].
  2. † – These probabilities are calculated using regression equations presented in Tables 2 and 3 of this paper (full models with all predictors). See Methods for details.
  3. ‡ – Post-test risk estimates are calculated by assuming that the pre-test 10-year CHD risk estimate represents an average of persons with different CAC scores, weighted by the probability of having a CAC score in each category. The risk in each category is calculated algebraically using relative risk estimates§ from a recent meta-analysis [7] (see Additional File 1).
  4. §-"Conservative" and "Optimistic" refer to assumptions made in a recent meta-analysis that attempted to quantify the value of CAC scores in predicting CHD events, independent of other CHD risk factors [7]. With conservative assumptions, relative risks associated with different CAC score categories were 1.7 (for CAC = 1–100), 3.0 (for CAC = 101–400) and 4.3 (for CAC>400) compared with a CAC score of zero. With optimistic assumptions, the corresponding relative risks were 2.1, 5.4, and 10.3.
  5. CHD – Coronary heart disease; CAC score – Coronary artery calcification score.