Methods to Estimate the Optimal Threshold for Normally or Log-Normally Distributed Biological Tests

Jérôme Jund, Muriel Rabilloud, Martine Wallon and René Ecochard
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Jérôme Jund: Department of Biostatistics, Hospices Civils de Lyon, Lyon, France, dim.jjund@ch-annecy.fr
Muriel Rabilloud: Department of Biostatistics, Hospices Civils de Lyon, Lyon, France
Martine Wallon: Department of Parasitology, Hospices Civils de Lyon, Lyon, France
René Ecochard: Department of Biostatistics, Hospices Civils de Lyon, Lyon, France

Medical Decision Making, 2005, vol. 25, issue 4, 406-415

Abstract: Putting a screening or a diagnostic test into everyday use requires the determination of its threshold. The authors present methods that yield a point and an interval estimation of the threshold that maximize the population utility whenever the test results are normally or log-normally distributed among healthy and among diseased subjects, with equal variances. These methods were assessed for bias, coverage probability, coverage symmetry, and confidence-interval width using simulation. They proved to be asymptotically nonbiased and to have a satisfactory coverage probability whenever the sample sizes of the healthy and the diseased subjects are equal to or greater than 50. The methods were next applied to determine an optimal threshold for the antibody load used to diagnose congenital toxoplasmosis at birth. The methods are easy to implement and impose few constraints; however, the sample sizes should be carefully determined according to the required accuracy.

Keywords: diagnostic test; optimal threshold; threshold estimation; toxoplasmosis; congenital; utility (search for similar items in EconPapers)
Date: 2005
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Citations: View citations in EconPapers (1)

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Persistent link: https://EconPapers.repec.org/RePEc:sae:medema:v:25:y:2005:i:4:p:406-415

DOI: 10.1177/0272989X05276855

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