A0324
Title: A system of urn models for incorporating informational borrowing in the design and inference of clinical trials
Authors: Rosamarie Frieri - University of Bologna (Italy) [presenting]
Andrea Ghiglietti - Universita degli Studi di Milano-Bicocca (Italy)
Giacomo Aletti - University of Milan (Italy)
Irene Crimaldi - IMT Lucca (Italy)
Alessandro Baldi Antognini - University of Bologna (Italy)
Abstract: A new design methodology is introduced for stratified comparative experiments based on a system of interacting urns. The key idea is to model the interaction between urns for borrowing information across strata and to use it in the design phase in order to i) enhance the information exchange at the beginning of the study, when only a few subjects have been enrolled and the stratum-specific information on treatments efficacy could be scarce, ii) let the information sharing adaptively evolves via an update mechanism based on the observed outcomes, for skewing at each step the allocations towards the stratum-specific most promising treatment and iii) make the contribution of the strata with different treatment efficacy vanish as the stratum information grows. In particular, the interacting urns design is introduced, namely a new covariate-adjusted response-adaptive procedure that randomizes the treatment allocations according to the evolution of the urn system. The theoretical properties of this proposal are described, and the corresponding asymptotic inference is provided. Moreover, by a functional central limit theorem, the asymptotic joint distribution of the Wald-type sequential test statistics is obtained, which allows for sequential monitoring of the suggested design in clinical practice.
