Modeling of Enrolment and Estimation of Parameters in Multicentre Trials
Modeling of Enrolment and Estimation of Parameters in Multicentre Trials
Vladimir Anisimov, Valerii Fedorov
ABSTRACT. We propose various stochastic enrolment models and derive probability distributions for the number of patients across the centres and the number of centres with a given number of patients. To estimate parameters of these distributions we use a few different estimators and find either analytically or using Monte Carlo simulation that these estimators produce very similar results close to the actual values of parameters.
We also analyze several GSK datasets and show that the enrolment model, where the patients arrive at centres according to Poisson processes with the recruitment rates sampled from a gamma distribution, is a parsimonious but °exible enough to describe actual data. It also helps to evaluate some features of the enrolment such as the expected number of “empty” centres or probability to have a centre with suspiciously large number of patients, etc. Finally, the model fitted to the historical data provides us the opportunity to design clinical trials for the similar drugs/treatments.
