[Inappropriate use of diagnostic laboratory tests--a perspective from decision making analysis].
BACKGROUND
The increasing use of diagnostic tests is probably not only a consequence of increased morbidity. It has been speculated whether some of the increase may be due to inappropriate use of diagnostic tests.


METHODS
The PubMed database was searched for literature relating to inappropriate use of laboratory tests. Bayes' theorem was used to explain the context dependence of results obtained from diagnostic tests and to calculate predictive values.


RESULTS
A theoretical discussion of tests and their use in diagnostic contexts is given, and a method for evaluating the appropriateness of testing is proposed. By calculating predictive values for positive and negative test results, the use of tests can be evaluated in a common probabilistic currency. Inappropriate usage can be defined as testing that does not give probabilistically useful information.


CONCLUSIONS
The method will be useful for practising physicians as a basis for improving test usage.
Ulvestad
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Avdeling for mikrobiologi og immunologi Gades Institutt Haukeland Sykehus, Bergen. elling.ulvestad@haukeland.no
D002624:Chemistry, Clinical / Q000592:standards*; D003657:Decision Making; D003936:Diagnosis, Computer-Assisted / Q000592:standards; D003951:Diagnostic Errors; D003955:Diagnostic Tests, Routine / Q000191:economics / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D007753:Laboratories / Q000592:standards*; D009664:Norway; D011237:Predictive Value of Tests; D011785:Quality Assurance, Health Care; D012680:Sensitivity and Specificity