Modern Approaches to Clinical Trials Using SAS: Classical, Adaptive, and Bayesian Methods

11.2 Classical Designs

11.2.1 Retrospective Design

Classical population enrichment designs fall into two categories: retrospective enrichment design and prospective enrichment design.

Retrospective enrichment design is a traditional all-comers design with retrospective validation of a biomarker, usually not available or assessable at the beginning of the trial, thereby making prospective testing unfeasible. Retrospective validation is conducted after the completion of the study and may involve previously conducted trials in the same patient population. As stated by Mandrekar and Sargent [1] when conducted appropriately, this design can aid in bringing forward effective treatments to marker-defined patient populations in a timely manner that ...