Observation strategy: Surgery is performed only if the patient is symptomatic. This is assumed to be an emergency operation.
Interventional strategy: Perform elective surgery now to correct the problem.
Parameters:
(1) incidence rate of disease progression (assumed to be constant)
(2) life expectancy
(3) mortality rate for emergency surgery
(4) mortality rate for elective surgery
life-time risk for acute symptoms requiring surgery =
= 1 - ((1 - (incidence rate))^(years of life expectancy))
risk of mortality with observation strategy =
= (life-time risk for acute symptoms) * (mortality rate for emergency surgery)
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Comparison of Risk
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Recommendation
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mortality for observation >> risk for elective surgery
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perform surgery
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mortality of the two strategies comparable
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discuss options with patient
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mortality for observation << risk for elective surgery
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observe
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Limitations:
• The model assumes that the incidence rate of disease progression is constant.
• The model assumes that the risk of serious complications for surgery is constant and does not increase with age.
• It is assumed that the person will have the average life expectancy for race and gender.
