Clinical Validity and Clinical Utility

Two questions after "does it measure correctly?"

A test can measure something precisely (see analytical validity) and still not be worth doing. Two further questions decide that. This page is information only and does not recommend or discourage any test.

• Clinical validity: how well does the thing being measured relate to the presence, absence or risk of a specific condition? MedlinePlus Genetics uses this meaning for genetic variants. [1]
• Clinical utility: can the test give helpful information about diagnosis, treatment, management or prevention? [1]

MedlinePlus adds that test takers, clinicians and insurers are often the ones who judge clinical utility. [1]

A ladder of evidence

A framework for diagnostic imaging describes six levels, from technical quality and diagnostic accuracy, through whether the information changes a clinician's thinking and the care plan, to effects on patient outcomes and finally societal costs and benefits. Success at each lower level is logically necessary but not sufficient for the next. [2] The same logic is useful for blood tests, genetic tests and wearable readings: a link between a marker and a disease does not show that testing for it helps people.

Researchers who evaluate genetic tests also look beyond deaths and illness. They weigh impacts on individuals, families and society, including psychological outcomes, though these are hard to measure well. [3]

What "valid" can and cannot cover

A test is often valid only for a specific group and purpose. The FDA recommends that studies state the condition of interest, the reference standard, the intended-use population and the study population. [4] A result in sick people sent to a specialist does not carry over to healthy people with no symptoms.

Three examples of specific uses

A blood test for Alzheimer's-related plaques. On May 16, 2025 the FDA cleared a plasma test measuring two proteins (pTau217 and beta-amyloid 1-42) as an aid in diagnosis. It is intended for adults aged 55 and older who already show signs and symptoms of Alzheimer's disease, in specialized care. [5] In a study of 499 plasma samples from cognitively impaired adults, compared against amyloid PET scans or spinal fluid tests, 91.7% of positive results and 97.3% of negative results matched, and fewer than 20% were indeterminate. [5] The FDA states it is not intended as a screening or stand-alone diagnostic test. [5] This is an FDA clearance of one named device for one indication, not approval of blood tests for Alzheimer's in general.

PSA for prostate cancer. The National Cancer Institute says the PSA test is not recommended for routine screening in the general population, and that most organizations suggest people discuss risks and benefits with a doctor first. [6] NCI lists false-positive results and overdiagnosis among the harms of PSA screening. [6] See overdiagnosis and screening vs diagnosis.

Wide panels and consumer tests. MedlinePlus notes that many direct-to-consumer genetic tests are not FDA-regulated, so their validity can be hard to judge. [1] Independent evidence that testing leads to better health is a higher bar than a lab report. For commercial panels see home lab testing and longevity clinic panels.

Biomarker, outcome, and decision

A changing marker is not the same as a better outcome. Read biomarkers vs clinical outcomes. A useful test usually changes what happens next: a different treatment, closer monitoring, or a justified decision not to treat. If nothing would change, the main effects of testing may be worry, cost and follow-up procedures.

Evidence labels used on this page

Established means widely used definitions and regulator statements read from official pages. Marketing claim means a statement from sellers that has not been shown by independent research.