SEMINAR IN LEICESTER
There will be a seminar in Leicester at 4.30 pm on Thursday,
14th January 1999 in Room G20, Department of Epidemiology and
Public Health, 22-28 Princess Rd West, Leicester.
Professor Deborah Ashby (Queen Mary and Westfield College,
London) will speak on:
`CASTING A SCEPTICAL EYE OVER THE DATA: IMPLEMENTING
BAYESIAN DATA MONITORING IN CANCER CLINICAL TRIALS'
All are welcome to attend.
Tea will be served in the common room from 4.00 pm.
If you are travelling from outside Leicester. Details of directions can be
found at
http://www.prw.le.ac.uk/epidemio/direct/
Alternatively call Jo Barker on 0116-252-3276 or myself for directions.
Abstract:
Classical data monitoring rules do not formally assess the impact
that the results of a clinical trial might have on clinical practice.
Bayesian rules have been proposed that overcome these difficulties.
We present details of their implementation in an oesophageal cancer
trial. We discuss practical issues encountered in implementation.
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'.
Paul Lambert
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Paul Lambert
Dept Epidemiology and Public Health
University of Leicester
22-28 Princess Road West
Leicester
LE1 6TP
UK
Tel: (0116) 252 5407
Fax: +44 116 252 3272
e-mail:[log in to unmask]
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