Why Diversity in Clinical Trials Is Important

By harming people of color and women more than other groups, the Covid-19 pandemic exposed a cruel reality: Factors such as gender, race and income can greatly affect access to healthcare, rates of disease, overall health and even life expectancy.

A key to reducing such health disparities is making sure to include diverse groups of people in clinical research. Understanding the effects of treatments on diverse populations is needed to ensure that everyone has access to high-quality, safe and effective treatments.

A brief history of diversity in clinical trials

In the 1960s and 1970s, the Food and Drug Administration (FDA) recommended leaving women of childbearing age out of drug trials to prevent potential harm. The policy extended to women who were not pregnant or not even likely to become pregnant. As a result, there was little data about how drugs affected women in general.

In the 1990s, Congress passed a law requiring NIH-funded research to include women and members of underrepresented groups. The policies led to major progress: According to the FDA, over half (56%) of people in trials for new drugs approved in 2020 were women. Three-quarters were white, 11% were Hispanic, 8% were Black and 6% were Asian. But more work still needs to be done.

“While there has been a concerted effort and recognition of the need for diversity in clinical trials, we are still lacking,” said Phyllis E. Greenberger, HealthyWomen’s senior vice president of science and health policy, and a long-time advocate for including women in clinical trials.

Even when studies include women and people of color, differences between groups are not always analyzed and the number of non-white, non-male participants are not always large enough to know if any differences are real or clinically relevant.

“It’s not a perfect system; studies are still being conducted that are not as diverse as we would like them to be,” said Wendy Nembhard, Ph.D., MPH, FACE, professor and chair of the Department of Epidemiology at the Fay W. Boozman College of Public Health; director of the Arkansas Center for Birth Defects Research and Prevention; and professor in the Department of Pediatrics at the University of Arkansas for Medical Sciences College of Medicine. “But the issue is on the table and effort is being made to address it … Investigators can no longer be silent on the issue.”

Progress may be on the horizon

Two influential organizations have recently made commitments to prioritize diversity. In April 2021, the Pharmaceutical Research and Manufacturers of America (Phrma), an advocacy organization representing the pharmaceutical industry, implemented new principles for the conduct of clinical research, including a commitment to ensuring diverse representation in clinical trials. And, on January 1, 2022, the New England Journal of Medicine, a leading medical journal, began requiring that authors submit data on the sex and gender, race or ethnicity, age, and geography of their study participants.

The importance of diversity

Diversity in clinical trials is not only an ethical issue; it’s also a practical one. Without including people of all genders and races in research, scientists can’t know for sure how different groups will respond to a treatment, leaving healthcare providers in the dark about how best to treat certain patients.

“We know there are ethnic and sex differences,” Greenberger said. “If therapies and devices are going to work differently in different populations, then they need to be studied in those populations before being prescribed.”

Lack of diversity in research can hide differences in side effects or adverse effects, according to Nembhard. These gaps are particularly important in certain conditions, such as preterm birth, that are known to affect women of color at higher rates than non-Hispanic white women.

Another glaring gap in clinical research participation is among pregnant women. Studying pregnant women is particularly sensitive because, according to Nembhard, researchers are asking women to potentially put themselves and their unborn baby into harm’s way.

“Pregnant women are reluctant to enroll in clinical trials with unknown or limited effects on the fetus or them[selves] during pregnancy, no matter how noble the scientific cause — which is understandable,” she said. “The burden of living with that guilt is unimaginable.”

But, she said, including more pregnant women in clinical trials is critical.

“We truly do not have accurate information about how medications and interventions affect pregnant women or the potential side effects,” Nembhard said. “Much of what we know comes from animal models, reports from pregnancy registries after the fact or hypothesized effects.”

Barriers to recruiting diverse participants

Many barriers to recruiting women and non-white participants into clinical trials exist. Topping the list is distrust of biomedical research among certain populations.

“Unfortunately, the history of unethical behavior toward [underrepresented people] in biomedical research is still fresh in people’s minds,” Nembhard said.

She cited the Tuskegee Syphilis study, in which researchers studied Black men with syphilis without offering them known treatment (penicillin) — without their consent. That study didn’t end until 1972, when an advisory panel concluded that it was unethical.

Nembhard also pointed to barriers such as language, cultural competency, and limited funding and personnel. Many studies include questionnaires that have only been validated in English or in mostly white populations. Making sure questionnaires are culturally appropriate and translating surveys into multiple languages can be challenging and expensive, as can hiring multilingual staff who can administer study protocols in different languages.

What needs to be done

Addressing very different barriers to diversify participation requires very different solutions. For example, Greenberger said telehealth is being considered for clinical trials where possible.

“Studies that address common barriers to participation such as transportation, childcare and clinic hours see an increase in participation of minority populations,” Nembhard said.

Addressing distrust is a thornier problem, but there, too, Nembhard sees opportunities.

“Partnering with communities of color in designing research studies or in the conduct of the study has proven to be very successful in increasing participation of minorities in research studies in general including clinical trials,” she said.

Additionally, Nembhard said that focus groups and community boards, which convene community leaders to serve as advisors to the research team, can be effective in guiding research design to address specific communities’ concerns.

“Many researchers have worked hard to build trust within communities and partner with members of the community to conduct research that benefits community members and the world of science,” she said.

This resource was created with support from Covis.