Factors affecting a screening test:
(1) disease factors
(2) testing factors
(3) therapeutic factors
Disease factors affecting a screening test:
(1) The disease must occur in an asymptomatic phase that lasts for a significant length of time.
(2) The disease must represent a significant burden to the population.
(3) The disease must lead to a bad outcome if left untreated.
Testing factors:
(1) The screening test must be able to detect the test during the asymptomatic phase.
(2) The screening test and subsequent follow-up tests must be acceptable to patients.
(3) The cost of the screening test should be cost-effective.
(4) The test should be highly sensitive for the target disease and show a reasonable specificity.
Therapeutic factors:
(1) There must be an effective treatment available that can cure or improve the outcome.
(2) The outcome for the disease must be better if the treatment is applied during the asymptomatic period than later in the course of the disease. Ideally there should be a chance for cure if treatment is given at an early stage of disease.
NOTE: It is necessary to distinguish a screening test from a screening program.
