When should CT calcium score be used? This simple calculator may help

In primary prevention, CT calcium scoring has been suggested to help decision making surrounding statin use.

Some of the underlying concepts are somewhat complex, but the screening paradigm remains that of matching the intensity of preventive efforts with the individual’s absolute risk.

The appropriateness of CT calcium scoring in an individual patient therefore depends on

-       patient’s pretest probability of atherosclerotic cardiovascular disease

-       potential benefits of preventive therapies

-       negative aspects and risks of preventive therapies

-       patient preference

In many cases, “patient preference” was the influencing factor and determines if CT calcium scoring is useful.

-       On one end of the spectrum, patients may be very risk averse and would prefer to be on preventive therapies despite lowish absolute risk of cardiovascular disease.

-       On the other end of the spectrum, patients may be very medication averse and would prefer NOT to be on preventive therapies despite highish absolute risk of cardiovascular disease

In these cases, this simple calculator may help us. From the MESA cohort data, we can obtain the probability of a non-zero CT calcium score and the predicted calcium score for an individual patient prior to the CT test, based on age, gender, and ethnicity alone.

These probabilities are incredibly useful for clinicians and patients. By considering the probabilities of various scores, including non-zero CT calcium score, it prompts clinicians and patients to carefully consider what they would do with the CT calcium score results. After considering the permutations of test results, one often arrives on a sensible strategy without performing such test. In other situations, one may find the probabilities of needing treatment vs. not needing treatment as toss-up, which reinforces the need for the CT calcium score test.

As case examples, try

(a) 65M, white, who is risk averse, and would like statins unless he has a calcium score of 0;

(b) 45F, Chinese, who is treatment averse, and would not want to be on a statin if at all possible.

The limitation of such calculator is that other risk factors are not taken into account, hence making it necessary for clinicians to adjust these probabilities.