Is the term “large-scale” intended to exclude rare diseases that may only have 10,000 to 20,000 patients, or does “large” relate to a significant portion of this total disease population?

The term “large-scale” is not meant to exclude rare diseases. The study should propose a sample size that is sufficiently large to allow for precise estimation of hypothesized effect sizes or for clear demonstration of non-inferiority; however, there is no absolute number associated with “large.” In addition, the sample size must support testing of an a priori hypothesis related to potential differences in effectiveness in relevant patient subgroups (heterogeneity of treatment effects). We welcome studies on rare diseases, provided that your study sample size is large enough to assure that the results will be valid and readily applicable to the population with the condition.