Medical treatments are developed on the basis of evidence. But evidence comes from the people who participate in clinical trials. When those people do not reflect the full diversity of the population, the evidence is incomplete.
This is not a theoretical problem. It has real consequences for health.
Clinical trial participation in the United States is skewed. White participants outnumber all other ethnic groups. Older adults participate at higher rates than younger people. Those with higher incomes and education levels are overrepresented. People from lower socioeconomic backgrounds, Hispanic and Black communities, Indigenous peoples, and other groups remain significantly underrepresented in trial populations.
This pattern has been consistent for decades. It is not accidental.
The reasons for underrepresentation are rooted in history and current reality. Medical mistrust in communities of colour is not baseless. Tuskegee and other documented abuses created justified skepticism about research systems. That skepticism persists.
Access barriers are concrete. Trials are often conducted at major research centres far from underserved communities. They require time off work and transportation. Many people cannot afford to participate, even if they want to.
Language barriers exclude non-English speakers. Trials are rarely offered in multiple languages, even in communities with significant non-English-speaking populations.
Cultural factors matter too. Some communities have been underserved by healthcare systems so consistently that distrust of any medical research is protective. Others have different health beliefs or decision-making structures that trials do not accommodate.
When treatments are tested primarily on one demographic group, we do not know how they will work for others. Differences in genetics, metabolism, and how bodies respond to medication are real. A drug dosage safe for a group of predominantly younger, white male participants may not be appropriate for women, older adults, or people of different ancestries.
Additionally, some conditions affect different populations differently. Cardiovascular disease presentations differ between men and women. Diabetes has different prevalence and outcomes across ethnic groups. Mental health conditions manifest differently across cultures. To understand how a treatment works, you need to study it in people who actually experience the condition in its full variation.
The lack of diversity in trials means many people receive treatment recommendations based on evidence that was not gathered from people like them.
Improving diversity in trials requires sustained effort on multiple fronts. Research institutions are beginning to invest in community partnerships—working with trusted local organisations, clinics, and leaders to build relationships and trust. This takes time. It requires genuine engagement, not performative outreach.
Trial design itself can shift to increase accessibility. Remote participation options can reduce transportation barriers. Multilingual staff and materials are non-negotiable. Flexible scheduling acknowledges that people have work, family, and financial constraints. Compensation should be meaningful.
If you belong to a community that has been underrepresented in clinical research—whether because of ethnicity, socioeconomic status, age, disability, language, or other factors—your participation matters enormously. This is not to place responsibility for fixing broken systems on individuals. It is to acknowledge that diverse participation directly improves how medicine works for everyone.
When you participate in a trial, you contribute evidence that can shape treatment for people in your community for decades to come. You also hold research teams accountable to accessibility standards and respectful engagement.
Building more representative trials is not quick. It requires researchers to listen to communities, acknowledge historical harms, remove structural barriers, and invest genuine resources. It requires funding agencies to prioritise diversity. It requires regulations that mandate diverse recruitment.
It also requires people from all communities to see clinical research as something that can be trusted and that matters to them.
If you are considering participation in a clinical trial, know that your involvement contributes to more complete medical knowledge. **trialport** can help you find trials and understand what participation involves.
