Assessing the Improved Discriminatory Power of a New Biomarker in Prognostic Models

• Activity Number: 422
• Type: Contributed
• Date/Time: Tuesday, August 3, 2010 : 2:00 PM to 3:50 PM
• Sponsor: Biometrics Section
• Author(s): Mei Liu*+ and Carol J. Etzel and Asha Kapadia
• Companies: MD Anderson Cancer Center and MD Anderson Cancer Center and The University of Texas School of Public Health
• Keywords: Prognostic models ; Discrimination ; Time-dependent NRI (tdNRI) ; Time-dependent IDI (tdIDI)

Abstract

Although the area under the receiver operating characteristic curve (AUC) is the most popular measure of the performance of prediction models, it has limitations; especially when it is used to evaluate the added discrimination of a new risk marker in an existing risk model. Pencina et al (2008) proposed two indices, the net reclassification improvement (NRI) and integrated discrimination improvement (IDI), to supplement the improvement in the AUC (IAUC). Their NRI and IDI are based on binary outcomes in case-control settings, which do not involve time-to-event. However, many disease outcomes are time-dependent and the onset time can be censored. Measuring discrimination potential of a prognostic marker without considering time to event can lead to biased estimates. We extended the NRI and IDI to time-to-event settings and derived the corresponding sample estimators and asymptotic tests.