A Bayesian method to estimate the optimal threshold of a longitudinal biomarker

✍ Scribed by Fabien Subtil; Muriel Rabilloud

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 194 KB
• Volume: 52
• Category: Article
• ISSN: 0323-3847
• DOI: 10.1002/bimj.200900242

✦ Synopsis

Abstract

The objective of this study was to develop methods to estimate the optimal threshold of a longitudinal biomarker and its credible interval when the diagnostic test is based on a criterion that reflects a dynamic progression of that biomarker. Two methods are proposed: one parametric and one non‐parametric. In both the cases, the Bayesian inference was used to derive the posterior distribution of the optimal threshold from which an estimate and a credible interval could be obtained. A numerical study shows that the bias of the parametric method is low and the coverage probability of the credible interval close to the nominal value, with a small coverage asymmetry in some cases. This is also true for the non‐parametric method in case of large sample sizes. Both the methods were applied to estimate the optimal prostate‐specific antigen nadir value to diagnose prostate cancer recurrence after a high‐intensity focused ultrasound treatment. The parametric method can also be applied to non‐longitudinal biomarkers.