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When advising an older
person about screening, one must estimate the individual's life
expectancy and decide if they will live long enough to benefit
from screening.
For example, as a woman
lives to be 80 or 90 years old, she must decide about tests and
treatments that would require her to live several years in order
to experience any benefit. This "time to benefit" is
of greater importance for very sick people, and is less important
for healthy people.
Consider these two
cases:
- Person in good
health - Mrs. Jones is a 70 year old who rates her health
as "excellent." She is physically and mentally active,
and participates regularly in social and community functions.
- Person in poor
health - Mrs. Smith is 75 years old, but rates her health
as "poor." She has congestive heart failure and can
barely get around the house because of weakness and shortness
of breath.
Now imagine you are
the clinician who must help each decide whether to undergo mammography
to screen for breast cancer. How would you decide if Mrs. Jones
and Mrs. Smith will live long enough to get benefit from breast
cancer screening?
You might:
- Estimate the life
expectancy for each woman
- Determine the "time
to benefit" for mammography
- Apply the results
in making your recommendation to screen (or not screen) for
breast cancer
Methods for estimating
life expectancy are explored in the sections that follow. In later
sections, you will have an opportunity to apply your knowledge
in solving interactive problems and questions.
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