Statistical Approaches to Accepting Foreign Clinical Data

In this paper, we discuss two issues about bridging studies described in the International Conference on Harmonization (ICH) E5 guideline. One of the issues is the basic concept of accepting foreign clinical data by performing bridging studies. The guideline does not mention why foreign data can be extrapolated to a new region through bridging studies. We introduce an “analogy” to clarify this. Another issue is the statistical approaches used to show the similarity between foreign data and the new region's data in a bridging study. We consider two cases: foreign data to show similarity that consist of one study or many studies.