Design and analysis of bridging studies with prior probabilities on the null and alternative hypotheses

Abstract The pharmaceutical industry and regulatory agencies are increasingly interested in conducting bridging studies in order to bring an approved drug product from the original region (eg, United States or European Union) to a new region (eg, Asian‐Pacific countries). In this article, we provide a new methodology for the design and analysis of bridging studies by assuming prior knowledge on how the null and alternative hypotheses in the original, foreign study are related to the null and alternative hypotheses in the bridging study and setting the type I error for the bridging study according to the strength of the foreign‐study evidence. The new methodology accounts for randomness in the foreign‐study evidence and controls the average type I error of the bridging study over all possibilities of the foreign‐study evidence. In addition, the new methodology increases statistical power, when compared to approaches that do not use foreign‐study evidence, and it allows for the possibility of not conducting the bridging study when the foreign‐study evidence is unfavorable. Finally, we conducted extensive simulation studies to demonstrate the usefulness of the proposed methodology.