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A note on Youden's J and its cost ratio

BACKGROUND: The Youden index, the sum of sensitivity and specificity minus one, is an index used for setting optimal thresholds on medical tests. DISCUSSION: When using this index, one implicitly uses decision theory with a ratio of misclassification costs which is equal to one minus the prevalence...

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Detalles Bibliográficos
Autor principal: Smits, Niels
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2959030/
https://www.ncbi.nlm.nih.gov/pubmed/20920288
http://dx.doi.org/10.1186/1471-2288-10-89
Descripción
Sumario:BACKGROUND: The Youden index, the sum of sensitivity and specificity minus one, is an index used for setting optimal thresholds on medical tests. DISCUSSION: When using this index, one implicitly uses decision theory with a ratio of misclassification costs which is equal to one minus the prevalence proportion of the disease. It is doubtful whether this cost ratio truly represents the decision maker's preferences. Moreover, in populations with a different prevalence, a selected threshold is optimal with reference to a different cost ratio. SUMMARY: The Youden index is not a truly optimal decision rule for setting thresholds because its cost ratio varies with prevalence. Researchers should look into their cost ratio and employ it in a decision theoretic framework to obtain genuinely optimal thresholds.