Clinical testing may be used for screening, diagnosis, and prognosis.
- 2.The following elements should be considered when ordering a diagnostic test:
Validity and repeatability characteristics of the test
Safety of the test
Pre-test probability of the disease
The natural history or seriousness of the disease without treatment
The benefits and risks of treatment
Patient preferences and costs
Diagnostic testing is most useful when the pre-test probability of disease is intermediate.
Likelihood ratios combine sensitivity and specificity characteristics for a specific test.