Validating Diagnostic Tests, Correct and Incorrect Methods, New Developments
Objective: To summarize correct and incorrect methods and new developments for that purpose.
Results and conclusions: A diagnostic test can be either qualitative like the presence of an elevated erythrocyte sedimentation rate to demonstrate pneumonia, or quantitative like ultrasound flow velocity to estimate invasive electromagnetic flow velocity.
Qualitative diagnostic tests can be assessed for
-accuracy using sensitivity / specificity / overall accuracy, and receiver operated (ROC) curves,
-reproducibility using Cohen's kappas,
-precision using confidence intervals of sensitivity / specificity / overall accuracy. Quantitative diagnostics tests can be assessed for
-accuracy using a linear regression line (y = a + b x) and testing a = 0.00 / b = 1.00,
-reproducibility using duplicate standard errors, repeatability coefficients or intraclass correlations,
-precision by calculating confidence intervals. Improved confidence intervals can be obtained by data modeling.
A significant linear correlation between the diagnostic test and the gold standard test does not correctly indicate adequate accuracy. A small mean difference between repeated measures or a significant linear relationship between repeated measures does not indicate adequate reproducibility.
New developments include continuous ROC curves, intraclass correlations, and Bland-Altman agreement tests for the accuracy assessments of quantitative diagnostic tests.
Keywords: Validation; accuracy; duplicate standard deviation; intraclass correlation; precision; qualitative and quantitative diagnostic tests; repeatability coefficients; reproducibility; sensitivity; specificity
Document Type: Research Article
Publication date: May 1, 2008
- Current Clinical Pharmacology publishes frontier reviews on all the latest advances in clinical pharmacology. The journal's aim is to publish the highest quality review articles in the field. Topics covered include: pharmacokinetics; therapeutic trials; adverse drug reactions; drug interactions; drug metabolism; pharmacoepidemiology; and drug development. The journal is essential reading for all researchers in clinical pharmacology.
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