Characterization of diagnostic tests.
Neurología (Barcelona, Spain), (September 2004)4361<m:linebreak></m:linebreak>LR: 20061115; PUBM: Print; JID: 9005460; ppublish;<m:linebreak></m:linebreak>Proves diagnòstiques; Introductori.Abstract
The primary aim of the diagnostic process is to establish the prevalence or probability of a disease given a certain clinical picture. A diagnostic test (DT) could be considered as every piece of information obtained from a patient. The DT can be done with technical devices, medical examinations or questionnaires. The DT offers information that allows us to classify patients according to a different probability to be sick. The operative validity of a test can be done in terms of diagnostic accuracy. It means the ability to truly classify a patient in the right clinical situation. Diagnostic accuracy is the quality of the information provided by a test (sensitivity, specificity). Diagnostic usefulness of a DT is the practical value of the information provided that does not have to coincide with the diagnostic accuracy. The operative validity allows us to classify the patients into different groups with different diagnostic, prognostic or therapeutic implications. The predictive value of a DT depends on its accuracy and the prevalence of the disease in the setting where the diagnostic process is to be made. Decision making with the information provided by the DT makes it necessary to consider the consequences of a false result.