Projection of power and events in clinical trials with a time-to-event outcome

In 2005, Barthel, Royston, and Babiker presented a menu-driven Stata program under the generic name of ART (assessment of resources for trials) to calculate sample size and power for complex clinical trial designs with a time-to- event or binary outcome. In this article, we describe a Stata tool called ARTPEP, which is intended to project the power and events of a trial with a time-to-event outcome into the future given patient accrual figures so far and assumptions about event rates and other defining parameters. ARTPEP has been designed to work closely with the ART program and has an associated dialog box. We illustrate the use of ARTPEP with data from a phase III trial in esophageal cancer.