Surrogate and auxiliary endpoints in clinical trials, with potential applications in cancer and aids research

TLDR

Surrogate endpoints, defined by Prentice, are response variables that can replace a true endpoint in clinical trials, while auxiliary endpoints are covariates that enhance true endpoint analyses by providing additional information on censored event times, particularly relevant in cancer and AIDS research. The study describes using augmented score and likelihood methods to incorporate auxiliary variables into analyses.

Abstract

Abstract Surrogate endpoints have been defined by Prentice as response variables that can substitute for a ‘true’ endpoint for the purpose of comparing specific interventions or treatments in a clinical trial. The applicability of this definition, and of related surrogate endpoint criteria, is discussed, with emphasis on cancer and AIDS research settings. Auxiliary endpoints are defined as response variables, or covariates, that can strengthen true endpoint analyses. Specifically, such response variables provide some additional information on true endpoint occurrence times for study subjects having censored values for such times. Auxiliary variables will very frequently be available, and they may be able to be used without making additional strong assumptions. Approaches to the use of auxiliary variables using ideas based on augmented score and augmented likelihood methods are described.