The Implication of Risk Factors II

We illustrate this with an example: assume that you have just been told that your risk for CHD in the next 10 years is 15%. You are offered a pill (a Statin?) that will reduce your risk. Such pills could reduce the risk of getting CHD by around 33%. Now we'll do some simple arithmetic:

  1. Without medication, your 10-year risk of getting sick is 15%. 15 people (on average) out of every 100 in your situation can be expected to get sick in 10 years

  2. On medication, the risk is reduced by 33%: it is reduced to 15 - 0.33x15 = 10%. So with medication, 10 people in 10 years will get sick.

  3. One way to look at this is to say: "we have given 100 people medication. As a result, after 10 years, only 10, rather that 15 people became ill".

So, what has the medication accomplished?

    As a consequence of giving the medication to all 100 patients,
85 people who would be well anyway, remain well!
10 people who would get sick anyway, get sick!
only 5 people have been positively impacted by the medication, not getting sick in the ten-year period.
95 people took medication that had no impact on them, except for the side effects!
even the five people who did not get heart disease in 10 years, could still get is later.

This has been recognized by a few in the medical establishment: Drs. Tan and Murphy (in Lancet, vol 354, p 1378, 1999) state concerning the statement that treatment saves lives - "The press are not the only culprits creating this problem because quite often, the researchers themselves condone or even initiate this perception."

Does the delay in illness for 5 people, justify giving medication to 100 people?

This is a personal decision. The next page will provide a calculator for you to use with your personal data.

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Last Modification - Nov 28, 2004