Statistical Review – Early Trial Cessation – When, Why and How to Interpret with Dr. David Harrington


Clinical trials can be stopped early for a range of reasons. But when that happens, it can be tricky to interpret the results and to understand the reasons why the trial was stopped in the first place. Join us in this episode of Curbside Consults with Dr. David Harrington, statistical editor at the NEJM, as we discuss the when, why and how to interpret a clinical trial that was stopped early.

00:00 - Introduction
00:35 - Review of Paper - Thrombolysis Guided by Perfusion Imaging up to 9 Hours after Onset of Stroke
01:15 - How is the size of a clinical trial determined any why is it important?
01:50 - Definition of "trial was stopped early"
02:37 - Reasons for stopping a trial early
04:16 - Limitations of interpreting outcomes of trials that have stopped early (underpowered)
05:04 - Do p-values need to change when a trial is stopped early?
05:35 - What are interim analyses, when and why are they performed?
06:00 - How should we interpret EXTEND?
08:20 - Take-aways

Additional Resources:
1. Ma et al. Thrombolysis Guided by Perfusion Imaging up to 9 Hours after Onset of Stroke. N Engl J Med 2019.
2. Viele K et al. Interpretation of Clinical Trials That Stopped Early. JAMA 2016.

The Curbside Consults series complements the foundational information in Rotation Prep by taking a deep dive into key clinical topics with expert clinicians and educators. These podcasts explore and critique the evidence behind clinical practice and break down statistical concepts for the busy clinical trainee.

 David Harrington is Emeritus Professor of Biostatistics and Statistics at Harvard T.H. Chan School of Public Health



 Angela Chen is a 2018-2019 NEJM editorial fellow. She is an endocrine fellow who trained at Flinders Medical Centre and the Royal Adelaide Hospital. Angela recieved her medical degree from the University of Adelaide, and masters of public health from the University of Sydney. Her clinical and research interests are in the areas of glucocorticoid and cardiovascular endocrinology and diabetes medicine.

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