Screening for heart disease

Part A. Screening for heart disease in a hypothetical population

A general practice physician examined a population of 2,000 adults in an attempt to detect heart disease. Assume that the prevalence of heart disease in this population of adults is known to be 10%, the sensitivity of the physician’s examination is 80% and its specificity is 80%. All adults who the general practitioner physician labeled as being “positive” (i.e., suspected of having heart disease) were referred to a cardiologist for further examination. The sensitivity of the cardiologist’s examination is 90% and its specificity is also 90%.

Use the plethora of 2×2 tables on page 3 to assist you in answering the following questions.

How many adults did the general practice physician label as “positive” for having suspected heart disease?
How many adults did the cardiologistlabel as “positive” for having heart disease?
What is the overall sensitivity of both examinations combined?
What is the overall specificity of both examinations combined?
What is the positive predictive value of the general practice physician’s examination?
What is the positive predictive value of the cardiologist’s examination?
How many adults do both the general practice physician and the cardiologist examine?

Alternative Scenario:Although this is unlikely to occur, suppose the order of the tests is reversed: the population of adults is examined first by the cardiologist and those deemed positive for having heart disease are then examined by the general practitioner.

Does the net sensitivity and/or net specificity of the two tests change?_
Only net sensitivity changes_
Only net specificity changes_
Both net sensitivity and net specificity changes_
Neither net sensitivity nor net specificity changes
What is the positive predictive value of the general practice physician’s examination in the alternative scenario?
In what order would you administer these examinations to minimize the number of adults tested twice?_
Have the general practice physician screen the population first_
Have the cardiologist screen thepopulation firstIs this order of giving the tests practical?_Yes_No
Why or why not?