The Absolute Risk - Actual Results

The following table will present results for the WHI study. It is very important to realize that this risk pertains to women whose average age was 63 at the beginning of the study (range between 50 and 79), 84% white, 50% of whom never smoked. If you are much younger, your AR may be much lower; conversely, if you are significantly older, your AR may be much higher. If you have CHD, smoke, or have other risk factors, your AR may be much higher. Consequently, these numbers should be used to understand the general magnitude of the AR, and not to calculate the risk for a particular person - the detailed data required to do that does not exist!

Absolute Risk**
Illness HRT     Placebo
Total CVD 15.7 13.2
    - CHD 3.7 3.0
    - Stroke 2.9 2.1
    - VTD* 3.4 1.6
Breast Cancer 3.8 3.0
Dementia 4.4 2.3
Colorectal Cancer 1.0 1.6
Fractures 14.7 19.1
Death 5.2 5.3
* Venous Thromboembolic Disease
** Number per 100 women per 10 years            
 
Time till Illness#
Illness HRT     Placebo
Total CVD 6 8
    - CHD 27 34
    - Stroke 35 49
    - VTD* 29 62
Breast Cancer 27 33
Dementia 23 44
Colorectal Cancer 98 62
Fractures 7 5
Death 19 19
# The number of years it takes for 10 women out of 100 to get the illness. Lower numbers mean higher risk.
Numbers are rounded to the nearest year.

Based on these tables, we now see what the largest risks to women in this group are:

  1. Cardiovascular Disease (CVD) that includes high blood pressure, hardening of the arteries, coronary heart disease, stroke, VTD and more.

  2. Fractures

Breast cancer and dementia involve a significantly lower risk for this group of women. While 16 women, out of a group of 100 women on HRT, will encounter CVD, and 15 will have fracture-related problems within 10 years, only 4 women in this group will encounter breast cancer and dementia. For women not on HRT, the corresponding numbers are 13 (lower risk) for CVD, 19 (higher risk) for fractures, 3 (lower risk) for breast cancer and 2 (lower risk) for dementia.

Interestingly, we note in passing that the actual death rate remains approximately 5 women in 100, for 10 years, regardless of whether they are on HRT, or not!

Another way of looking at this, is that it will take only six years (rather than 8) for ten women out of 100 (approximately) to encounter CVD, if they are on HRT. Avoiding HRT "gives" them two more years till all the 10 women develop CVD symptoms. The other numbers are in the right-hand table, above.


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Last Modification - July 11, 2004