Relevant Risk verus Absolute Risk

[BettyBoop]

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http://www.businessweek.com/magazine/content/08_04/b4068052092994.htm?chan=magazine+channel_top+stories

Note: (NNT)= number needed to treat.

Drug Co's advertise their products using Relative Risk Reduction. They downplay the side effects using Absolute Risk Reduction.

Here's a 5-year study for women as an example:
Group A take a drug to reduce breast cancer
100 women = Group A

Group B take a placebo to reduce breast cancer
100 women = Group B

After 5 years
In Group A, 2 out of 100 get cancer = 2%
In Group B, 4 out of 100 get cancer = 4%

Relative Risk reduction: means that OUT OF the TOTAL women who GOT CANCER (total 6)
2 got cancer using the drug
4 got cancer using placebo
so, 50% relative risk reduction if you take the drug.

Absolute Risk reduction: (is more precise).
Group A = 2 get cancer out of 100 women
* so 2% of 100 women got cancer taking the drug

Group B = 4 get cancer out of 100 women
* 4% of 100 women got cancer taking placebo

Using an "absolute" comparison of Group A & B, it shows that of the 4% of women who developed cancer while taking placebo, 2% developed cancer while taking cancer prevention medication.

4% - 2% = 2% ABSOLUTE RISK REDUCTION

Now let's assume the cancer prevention medication is very expensive AND has intolerable side effects. Would you still take the drug over 5-years if you knew it only had a 2% risk reduction?

If you had an alternative to taking medication:
Eat a healthy diet, exercise, take yoga and get regular checkups (annual mamograms)does this sound better to you?

 

[kid007]

Well i agree we should eat an healthy diet if we don't want take a risk with our lives.......

 

[MOHS_01]

We have know this for years -- the first example that comes to mind is thrombolytic therapy for acute MI's. Relative risk reduction is a useful tool for comparing two treatments with regards to outcomes.

Another example (a little closer to my heart) is comparing Mohs micrographic surgery to standard surgical exision. Commonly touted figures for primary BCC:

standard excision: 92% 5yr recurrence free rate
MMS: 99% 5yr recurrence free rate

absolute risk reduction of 7%
relative risk reduction of 800% !

 

[turkeyjerky]

I'm not quite sure why you think that yoga is going to prevent cancer. What's the NNT to treat on that?