ABSTRACT
This chapter uses both terms-multiregional and multinational. In trials that recruit from very few countries, each with sizeable numbers of participants, “multinational” is often the more appropriate term. “Multiregional” is more applicable for trials that recruit from two or more groups of countries, where each group has similar cultural backgrounds and practice similar approaches to treating patients, or that share regulatory agencies. For any given trial, the sponsor and Steering Committee should define the method to be used for classifying participants by country, by groups of countries, by geographical proximity, or by some other relevant system of categorizing countries. Moreover, in a given multiregional trial in which most of the data are presented by region, the IDMC might want to see some data by country. For example, in a study in which one region is the European Union, an IDMC may want to see data by country, or by groups of countries, if the standard of care within the European Union differs widely from country to country. As another example, in studying a treatment for malaria in three regions of interest (Asia, South America, and Africa), the country-specific prevalence of disease within each of these regions may be so different that country-specific data are important for the IDMC to review.
