The next meeting of the Glasgow local group will be Thurs 21st Jan at
5.30pm on Level 6 of the Boyd Orr Building, Glasgow University.
The speaker is Professor Deborah Ashby , Dept of Environmental and
Preventive Medicine,Queen Mary and Westfield College
Her talk is entitled
`Casting a Sceptical Eye over the Data':
Implementing Bayesian Data Monitoring in Cancer Clinical Trials
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Abstract
Many clinical trials organisations use regular interim analyses to
monitor the accruing results in large clinical trials. Classical
rules, such as the group-sequential procedures of Peto, O'Brien and
Fleming or Pocock have traditionally been based on P-values.
However, none of these rules formally assess the impact that the
results of a clinical trial might have on clinical practice. Thus a
trial might be terminated early because of apparent treatment
benefit, but fail to influence future clinicians to modify their
future treatment policy. Bayesian rules have been proposed that have
the potential to overcome these difficulties (Freedman, Spiegelhalter
and Parmar, Statistics in Medicine, 1994). Like many Bayesian
techniques, they were originally presented as reanalyses of trials
that have already been published. They are now being used `live'
(Fayers, Ashby and Parmar, Statistics in Medicine, 1997). We present
details of their implementation in a trial of surgery with and
without pre-operative chemotherapy for oesophageal cancer. Practical
issues encountered will be discussed, including the choice of prior
distribution and `clinically relevant' values for use in monitoring,
and presentation of ideas to clinical members of the data monitoring
committee. As one clinician put it `It's just casting a sceptical eye
over the data'.
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All welcome
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