Screening Tests are used in persons who have no symptoms of a specific disease, but may have the early stage of the disease or the stage just prior to the disease. The following things are different between screening tests and diagnostic tests:
- With screening tests, the number of affected persons is likely to be small
- With screening tests, questions may arise about whether or not taking action will be helpful.
- If a screening test is costly and only a small number of people are likely to be identified with early disease, it may be hard to justify doing the test. r It is costly to screen large number
- It is costly to screen large numbers of people, most of whom will not have the condition for which screening is being done.