The topic of diversity in clinical trials is rising to the forefront of many conversations in evidence-based medicine, and efforts are being made to improve the diversity of clinical trials. However, there is little uniformity in the methods used to evaluate these efforts. In this article, we describe our Clinical trial Diversity Rating (CDR) framework and the development process, including the broader considerations for evaluating the demographic diversity of clinical trials and their implications, and demonstrate its use through an illustrative example.

Study Design and Setting

The development of the framework was a four-step process, including a scoping review, a cross-sectional study, creation of the tool, and integration of feedback from an advisory group.


Our scoping review identified 110 publications that examined clinical trial diversity. Race/ethnicity, sex, and age were the most common characteristics evaluated. About 85% clearly defined the benchmark used for evaluation, but less than half (48%) used disease prevalence as the benchmark. Only 64% of studies defined what would be considered adequate representation. The cross-sectional study, which applied some of the approaches identified in the literature, helped to identify the complexities of evaluating multinational trials and certain demographic characteristics. Key decisions for the CDR framework, such as the demographic characteristics to be evaluated, the benchmark and thresholds for evaluation, and how these factors contribute to the overall rating of clinical trial diversity, were informed by the two earlier phases and feedback from an advisory group.


The CDR framework provides an objective and transparent approach to evaluating clinical trial diversity. Groups such as Health Technology Assessment bodies, clinical trial regulators, policymakers, journal editors, and individual researchers can use this tool to examine, monitor, and improve diversity in clinical trials.