Interphase clinical trials: Phase III/Phase IV

In this paper we investigate ways in which the results of a controlled Phase III clinical trial can be used in subsequent Phase IV, and possibly further Phase III studies. Specifically we are interested in; 1) developing particular hypothesis relating to a modified study population, 2) studying how changes in the particularities of the Phase III study group can influence certain outcome variables of interest and 3) using the results of the Phase III study applied to specific target groups, having particular characteristics, to updating observations from the Phase III study with information obtained at a later stage. These issues are all concerned with the way in which we can exploit information from a Phase III trial, information that is of high quality but not necessarily directly related to the way in which many post Phase III studies, focussing on different patient population groups, are carried out. Since it is often these post Phase III studies that have the strongest influence on clinical practice we aim to develop a framework around which the post Phase III studies might be structured.