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College of Arts & Sciences
Department of Statistics


Butch Tsiatis Palmetto Lecture 2

Friday, March 25, 2016 - 2:30pm

Statistics Department Palmetto Lecture 2

Where: Capstone Building, First Floor Conference Center

Speaker: Anastasios (Butch) Tsiatis

Affiliation: North Carolina State University, Department of Statistics

Title:  2016 Palmetto Lecture 2: Inference on treatment effects from a randomized clinical trial in the presence of premature treatment discontinuation: The SYNERGY trial

Abstract: The SYNERGY trial was a randomized, open-label, multi-center clinical trial designed to compare two anti-coagulant drugs on the basis of various time-to-event endpoints. As usual, the protocol dictated circumstances, such as occurrence of a serious adverse event, under which it was mandatory for a subject to discontinue his/her assigned treatment.  In addition, as in the execution of many trials, some subjects did not complete their assigned treatment regimens but rather discontinued study drug prematurely for other, ``optional'' reasons not dictated by the protocol; e.g., switching to the other study treatment or stopping treatment altogether at their or their provider's discretion.  In this situation, as an adjunct to the usual intent-to-treat analysis, interest may focus on inference on the ``true'' treatment effect; i.e., the difference in survival distributions were all subjects in the population to follow the assigned regimens and, if to discontinue treatment, do so only for mandatory, but not optional, reasons.  Approaches to inference on this effect used commonly in practice are ad hoc and hence are not generally valid.  We use SYNERGY as a motivating case study to propose generally-applicable methods for estimation and testing of this ``true'' treatment effect by placing the problem in the context of causal inference on dynamic treatment regimes. Analysis of data from SYNERGY and simulation studies demonstrate the utility of the methods.

This work is joint with Marie Davidian and Min Zhang