ESTIMATING THE PROPORTION OF TREATMENT EFFECT EXPLAINED BY A SURROGATE MARKER

Citation
Dy. Lin et al., ESTIMATING THE PROPORTION OF TREATMENT EFFECT EXPLAINED BY A SURROGATE MARKER, Statistics in medicine, 16(13), 1997, pp. 1515-1527
Citations number
18
Categorie Soggetti
Statistic & Probability","Medicine, Research & Experimental","Public, Environmental & Occupation Heath","Statistic & Probability","Medical Informatics
Journal title
ISSN journal
02776715
Volume
16
Issue
13
Year of publication
1997
Pages
1515 - 1527
Database
ISI
SICI code
0277-6715(1997)16:13<1515:ETPOTE>2.0.ZU;2-4
Abstract
In this paper, we measure the extent to which a biological marker is a surrogate endpoint for a clinical event by the proportional reduction in the regression coefficient for the treatment indicator due to the inclusion of the marker in the Cox regression model. We estimate this proportion by applying the partial likelihood function to two Cox mode ls postulated on the same failure time variable. We show that the resu ltant estimator is asymptotically normal with a simple variance estima tor. One can construct confidence intervals for the proportion by usin g the direct normal approximation to the point estimator or by using F ieller's theorem. Extensive simulation studies demonstrate that the pr oposed methods are appropriate for practical use. We provide applicati ons to HIV/AIDS clinical trials. (C) 1997 by John Wiley & Sons, Ltd.