Multinational (Global) Trial

Abstract

Multinational clinical trials are trials conducted in more than one country using a common protocol. They have become increasingly common and have many advantages, such as access to a large patient population and the potential to obtain a broadly generalizable conclusion. However, these trials also have a number of practical difficulties, such as differences among the countries in language, import/export procedures, and regulatory and legal requirements. In addition, country‐by‐treatment interactions have frequently been found in these trials, leading to difficulties in interpreting the results. For example, the MERIT‐HF trial, which evaluated metoprolol in patients with heart failure, found an overall hazard ratio for total mortality of 0.66, but a hazard ratio of 1.05 in the United States. There is particular concern that differences among countries hinder the ability to evaluate the cost effectiveness of an experimental treatment.