Continual Reassement Method (CRM)
We are analysing a dose-finding phase I clinical trial. The method used
is the CRM using a Bayesian approach (Chevret Stat Med,
1993-1093-1108):
6 doses are available. For each of them an a priori probability of
toxicity is chosen.
The mathematical model for dose-response is:
p(i)=(exp(3+alpha.x(i)))/(1+exp(3+alpha.x(i))) (logistic model)
We assign the first patient to the j dose. After observing the
dichotomous outcome of toxicity, the posterior distribution of alpha
would be calculated via Bayes theorem.
This process continues until we reach a predetermined fixed sample size.
We would like to calculate
-the intermediate a posteriori probability curves at each step
- the confidence intervals of these probabilities (and therefore the SE of alpha).
Do you think there is some SAS solution to do that?
Otherwise how can we proceed?
Thanks
Gabrielle Boissard
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