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Example: A 75-year-old
woman wants to know if she should undergo screening mammography.
Her self-reported health status is poor, and she has a history
of congestive heart failure.
Assess risk
and review screening history: no exposure to estrogen, inconsistent
past screening history; no family history of breast cancer.
She is at average risk.
Using self-reported
health status and, adjusting for co-morbid conditions, determine
physiological age and estimate life expectancy:
- Physiological
age from Table (click here
for table) = 82
- Life expectancy
estimate from age 82 assuming that the 5-year mortality
rate for CHF is 50% = 3.5 years (click here
for graph)
Determine the time
delay between initiating screening and observing a reduction
in breast cancer mortality.
- Delay between screening and benefit in mammography = 5
year (click here for
the evidence)
- Since delay
is greater than life expectancy, do not screen.
If life expectancy
is greater than the time delay until benefit, determine preferences
for screening and treatment.
Here is a graph showing
life expectancy for healthy women (upper curve) and women with
congestive heart failure (lower curve) at a particular age.
- The vertical axis
is life expectancy (in years).
- The horizontal axis
is a person's age.
To obtain a person's
life expectancy, find the person's age on the horizontal axis,
draw a vertical line up to the curves, and read the person's life
expectancy from the vertical axis.
- If you know the
person's health status, use their physiological age.
- If you don't know
person's health status, use their chronological age.
| Figure
3.7.2: Determining Estimated Life Expectancy
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This graph is specific
for women with congestive heart failure. If the woman had chronic
lung disease or angina pectoris, you would have to create a new
table. The steepness of the line describing life expectancy with
the chronic illness will vary from illness to illness depending
on the death rate from the illness.
There is a strong theory
behind these calculations of life expectancy with chronic illness.
If you are interested in learning about how to calculate the person's
life expectancy with and without taking into account their chronic
illness, click here.
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