Events and Seminars : 2012 Seminars

Lessons Learned From An Ongoing Clinical Trial: The SPS3 Experience

The Secondary Prevention of Small Subcortical Strokes (SPS3) study is an on-going clinical trial assessing the efficacy of two interventions for preventing recurrent strokes. Participants are randomized in a 2×2 factorial fashion to receive either combination antiplatelet therapy or aspirin alone, and to receive blood pressure lowering interventions with goals of lower systolic blood pressure to one of two target ranges. During the conduct of the study, several interesting statistical issues have arisen. In this talk, I will focus on the operating characteristics of two of these issues. First, I will discuss the approach we took to monitor futility in this 2×2 factorial study. I will describe the properties of our method, compared to other ways to monitor futility in this situation. Second, I will discuss a mid-study modification that was made to the sample size, due to a lower than expected observed overall event rate during the course of the study. I will focus on the impact of the design modification on overall power and Type I error.

May 23, 2012