Stats
Group Sequential Monitoring of Clinical Trials in R (December
13, 2005).
Category: Early stopping in clinical trials
It is very expensive to purchase software that performs group sequential
monitoring of clinical trials (sometimes called interim analysis). Group
sequential monitoring is looking at a trial at selected time points during
the study to see if you should stop the study early. There are a couple of
functions in R that will do simple calculations, and the price, of course, is
free.
The
HMisc library created by Frank Harrell has a function ldBands that uses
the Lan-DeMets method with flexible alpha spending functions.
The
seqmon library created by David A. Schoenfeld has a seqmon function that
uses the algorithm by Amitage, McPherson and Rowe. An example they cite shows
boundaries using the O'Brien Fleming approach.
I will try to document some of the details of these algorithms and test
them against some well known examples when I have time.
Further reading:
Stats >> WebLog
>> Group Sequential Monitoring of Clinical Trials in R (December
13, 2005, Ethics, Early stopping)
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