Why Diversity in Clinical Trials Matters More Than You Think
A drug that works in a 45-year-old white man may not work the same way in a 70-year-old Black woman, a young Hispanic man, or an Asian child. That is not a hypothetical. It is the core argument of the Clarity Clinical Solutions video "Why Diversity in Clinical Trials Matters More Than You Think," and it is grounded in decades of documented failures.
Clinical trials have historically enrolled narrow, homogeneous populations. The video calls this not just unfair but dangerous medicine. When a drug is tested on a group that does not reflect who will actually take it, the people left out pay the price.
Who has been missing from trials
The video runs through the enrollment numbers, which come from the video itself and are widely echoed in the research literature: roughly 80% of trial participants in the U.S. have been white, despite white people being about 60% of the population. Black participants have made up about 10% of trial participants despite being about 13% of the population. Hispanic participants have been around 5% despite being about 19%. Asian representation has been under 2%. Older adults over 65 make up the biggest share of drug users, but only about a third of trial participants.
Those gaps matter because drugs do not behave the same in everyone. Genetics, metabolism, and physiology all shift how a drug is absorbed, processed, and eliminated. The CYP450 enzyme system, which metabolizes most drugs, has variants distributed differently across populations. Women metabolize many drugs differently than men.
The consequences are not abstract. The video cites the FDA's finding that eight of ten drugs withdrawn from the market between 1997 and 2001 posed greater health risks for women, risks that went undetected because trials enrolled mostly men. The FDA's own women's health research program exists in part because of that history.
BiDil and warfarin: two cases that prove the point
BiDil is the textbook case. The first drug approved specifically for heart failure in Black patients, it was approved by the FDA in 2005 after a trial in about 1,050 self-identified Black patients showed a 43% reduction in mortality. Earlier trials in mixed populations had not shown a statistically significant benefit. Critics are right that race is a rough proxy for genetics, but the video's point stands: without diverse enrollment, an effective therapy would have been discarded. The drug's label is still searchable through DailyMed.
Warfarin tells the same story in dosing. Black patients typically need 20 to 30% higher doses to reach the same anticoagulant effect, differences largely explained by variants in the VKORC1 and CYP2C9 genes. For decades, one-size-fits-all dosing was standard. The FDA now includes race-specific dosing information in the label, but only because studies with diverse patients revealed the difference.
Women: a history of outright exclusion
The exclusion of women was policy, not accident. In 1977, the FDA banned women of childbearing potential from early-phase trials. The policy lasted until 1993, which the video notes meant sixteen years of drugs tested almost exclusively on men.
The damage showed up in the real world. Women experience adverse drug reactions at nearly twice the rate of men. The sleeping pill Ambien (zolpidem) is the famous example: it was approved at a dose that proved too high for many women, and the FDA did not require the lower recommended dose for women until 2013, roughly two decades after approval. The video tells this story, and it is worth reading the FDA's women's health research page for the broader context on how drug response differs between men and women.
The regulatory shift: from voluntary to required
Underrepresentation is no longer just an ethical argument. It is now a legal requirement. The Food and Drug Omnibus Reform Act of 2022, FDORA, requires sponsors to submit diversity action plans for late-stage clinical trials, with enrollment goals broken down by age, ethnicity, sex, and race. The FDA can reject or delay an application if the plan is inadequate or was not followed.
The NIH got there first. The NIH inclusion policy has required the inclusion of women and minorities in NIH-funded clinical research since the 1993 NIH Revitalization Act, and the policy on women and minorities in clinical research explains how that plays out in practice. Progress has been uneven. NIH-funded trials now enroll roughly equal numbers of men and women, but racial diversity remains poor, and the video cites incomplete race reporting in a large share of trials. Mandates alone are not enough. They need enforcement and community engagement.
Why participation still lags
The barriers are well documented and the video lists them plainly:
- Mistrust rooted in real history, including the Tuskegee syphilis study and the use of Henrietta Lacks' cells without consent.
- Site geography. The video cites that most trial sites sit in white, affluent neighborhoods, which makes participation hard for everyone else.
- Eligibility criteria that exclude patients with common conditions more prevalent in minority populations.
- Economic barriers. Trials can cost patients time, travel money, and lost wages.
What actually works
The solutions are also known. Community partnerships with health centers, churches, and community organizations increase enrollment from underrepresented groups, in some cases by two to four times. Decentralized trials using telehealth and mobile nurses reach rural and low-income populations that would never travel to a big academic center. And broader eligibility criteria let trials reflect real patients instead of idealized participants.
Precision medicine raises the stakes. The video notes that most genomic data comes from people of European descent, who are a minority of the global population. That skew makes genetic risk scores and drug-metabolizing databases less accurate for everyone else. The NIH's All of Us research program, as described in the video, is aiming to collect genomic and health data from a million diverse Americans to fix exactly that imbalance.
The bottom line
Diversity in clinical trials is not a box to check. It is a scientific necessity. Every drug approved on a narrow evidence base carries a hidden risk for everyone outside the tested population. The FDA now requires diversity action plans, the NIH has required inclusion for decades, and the evidence from BiDil, warfarin, and Ambien shows what happens when researchers get it right and when they get it wrong. Trials that enroll the people who will actually use the drug produce better medicine for everyone.
This article is based on the Clarity Clinical Solutions video "Why Diversity in Clinical Trials Matters More Than You Think." Watch it here: Why Diversity in Clinical Trials Matters More Than You Think
References
- Clarity Clinical Solutions — "Why Diversity in Clinical Trials Matters More Than You Think" (source video; enrollment statistics, BiDil, warfarin, Ambien, FDORA, and All of Us sections). https://www.youtube.com/watch?v=BsXAlb-y0NQ
- NIH — Inclusion of Women and Minorities as Participants in Research Involving Human Subjects (supports the NIH Revitalization Act inclusion discussion). https://grants.nih.gov/policy/inclusion.htm
- NIH — Women and Minorities in Clinical Research (supports the NIH inclusion policy discussion). https://grants.nih.gov/policy/inclusion/women-and-minorities.htm
- FDA — Women's Health Research (supports the drug safety differences between men and women discussion). https://www.fda.gov/science-research/science-and-research-special-topics/womens-health-research
- NIH DailyMed — BiDil search results (supports the BiDil drug and labeling discussion). https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=BiDil