OBJECTIVES: Regulatory agencies worldwide have released guidance to improve diversity in clinical trials with the goal of redressing established disparities in health research and the consequent inequities in health outcomes. The success of these regulatory changes depends on the extent to which they can be actioned. The objective of our work was to map the landscape of regulatory agencies’ guidelines pertaining to diversity in clinical trials and to evaluate their implementability.

METHODS: An online search was conducted to identify English-language guidance on diversity in clinical trials from regulatory agencies serving large markets worldwide. Key search terms included: “diversity OR representative”, “trial”, and “[regulator]”. Information was extracted on guideline stage of development, enforceability, and on prioritized, underrepresented populations. Assessment of regulatory guidance was performed using a modified version of the Guideline Implementability Appraisal tool (GLIA 2.0), a validated tool for appraising the implementability of clinical guidelines. It assesses nine domains that impact implementability: executability; decidability; validity; flexibility; effect; measurability; novelty/innovation; and computability.

RESULTS: We identified four agencies with guidance statements: the European Medicines Agency (EMA); the Food and Drug Administration (FDA); Health Canada; and the United Kingdom’s Medicines and Healthcare products Regulatory Agency (MHRA), which was not yet available. Guidance varied in stage of development and enforceability: the EMA and Health Canada required justification if guidance was not followed, whereas the FDA’s draft guidance was non-binding. Prioritized populations differed between the three agencies. Despite being a draft, the FDA guidance was assessed as the most implementable, scoring nine out of nine on GLIA 2.0 global domains.

CONCLUSIONS: Recent regulatory initiatives to improve representativeness of clinical trials varied in development stage, enforceability, prioritized populations and degree of implementability. Efforts to improve diversity in clinical trials must be sustained to achieve significant impact.