Many diagnostic tests are not based on good evidence

Many diagnostic tests and tests used to monitor disease are not supported by high quality evidence, finds a study in this week’s BMJ.

Researchers examined how many common clinical tests used in one respiratory medicine clinic in the UK were based on high quality evidence (evidence was graded according to a recognised quality scale).

Only half the tests that were used to make or exclude a diagnosis and a fifth of the tests used to assess a known condition were supported by high quality evidence.

This study reflects the practice in a single unit and the proportion of evidence based tests used elsewhere may be higher, stress the authors. Nevertheless, there is a clear need for further high quality research into medical tests, at least in this specialty. There is also a need for an evidence base for the use of trials of therapy.