Women, and specifically women of color, are underrepresented in clinical trials, limiting biological understanding and contributing to health inequities and social injustice. Analyses of barriers to inclusion suggest practical interventions that together create a roadmap of specific and actionable steps to increase diverse representation in research and sustainable change.

Introduction

The safety, efficacy, and effectiveness of medicinal products depends upon the review and approval of planned clinical trials by impartial regulatory bodies including ethical review boards and health regulatory agencies. The practical adoption of study findings, however, depends upon the interpretation, communication, and strength of the results, and then upon the decisions and actions of healthcare practitioners and the public. Participation in clinical trials, therefore, should generally represent those affected by the disease or condition and for whom the intervention or product is intended, and that in turn depends upon the epidemiology of the condition or the intended use of the product. In the absence of appropriate epidemiological data relating to the incidence and severity of the condition being studied, participation should generally reflect the general population, with appropriate safeguards to protect vulnerable populations.

But what is representativeness, and how specific need one be? At one extreme, evaluating for every subgroup in a statistically meaningful way would require infinitely large clinical trials. At the other extreme, the concept of personalized medicine would imply that robust trials of specific subgroups are unnecessary, since every individual is unique. The practical compromise is to ensure that the evidence base for medicinal products is robust for major subgroups and that the collection of data for certain populations and for certain questions continues thereafter.

Historically, women have been underrepresented in clinical trials, but there has been a steady increase in the representation of women over the last several decades—in part a consequence of laws, regulations, policies, and guidance.1 However, in certain therapeutic areas, women remain underrepresented in, and underserved by, clinical trials despite efforts to mitigate the lack of inclusion, and that underrepresentation is significantly more acute for women of color. In this text, the term “women” is used to represent biological sex at birth. While many of the same issues discussed here apply to sexual orientation and gender identity, a topic deserving of thorough exploration, we are unable to consider these further in this short commentary. Here we examine factors that impact inclusion, biological and societal consequences of failing to correct underrepresentation, and multiple practical changes that can and should be introduced to advance inclusion.