Statistics and Data Science Seminar
Lihui Zhao
Northwestern University
Design and Analysis of Clinical Studies using Restricted Mean Survival Time
Abstract: For a study with an event time as the endpoint, its survival function contains all the information
regarding the temporal, stochastic profile of this outcome variable. The survival probability at a
specific time point, say t, however, does not transparently capture the temporal profile of this
endpoint up to t. An alternative is to use the restricted mean survival time (RMST) at time t to
summarize the profile. The RMST is the mean survival time of all subjects in the study population
followed up to t, and is simply the area under the survival curve up to t. The advantages of using
such a quantification over the survival rate have been discussed in the setting of a fixed-time
analysis. In this research, we generalize this approach by considering a curve based on the RMST over
time as an alternative summary to the survival function. Inference, for instance, based on
simultaneous confidence bands for a single RMST curve and also the difference between two RMST curves
are proposed. The latter is informative for evaluating two groups under an equivalence or
noninferiority setting, and quantifies the difference of two groups in a time scale. In addition, we
extend RMET to the setting of multiple endpoints, which includes classical competing risks and
semi-competing risks. The methods are illustrated with the data from two clinical trials.
Wednesday October 26, 2016 at 4:00 PM in SEO 636