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Why Black People Remain Underrepresented in Clinical Trials

Why Black People Remain Underrepresented in Clinical Trials

There has been increasing awareness around the need for improving inclusion and diversity in clinical trials. As such, there has been a growing emphasis on efforts to achieve better and more accurate representations of minority and underrepresented populations like Black people in clinical studies.

Healthcare system inequities among Black communities in North America have a long history rooted in socioeconomic disparities bred from centuries of systemic racism. And Black people continue to face generational disenfranchisement in healthcare systems and medical research.

This is especially concerning as Black people have a high risk of serious, but often treatable/manageable diseases like diabetes and high blood pressure. They are also at a high risk of developing heart disease and stroke. Diabetes is 60 percent more prevalent among Black people than white people. In addition, Black individuals have a 5.6 times greater risk of developing kidney disease and are 2.3 times more likely to undergo a limb amputation associated with diabetes compared with other individuals. They are also more likely to develop hypertension earlier in life than white individuals.

Despite these statistics, in the US, Black people only constitute five percent of all clinical trial participants. The overwhelming majority of trial participants nationwide are white. According to a drug trials report from the US Food and Drug Administration (FDA), of the 32,000 participants in trials that supported the approval of 53 drugs by the agency’s Center for Drug Evaluation and Research (CDER) in 2020, only eight percent of the participants were Black and 75 percent were white. Black people were only second to Asians (six percent) with respect to lowest trial representation.

Black populations are underrepresented in clinical trials due to a myriad of factors. These include mistrust/distrust of medical and scientific communities, inadequate access to healthcare, cultural barriers, lack of health education, failure of healthcare providers to adequately engage and educate patients about trials and investigators failing to actively recruit Black participants in trials.

Underrepresentation in clinical trials is a part and parcel of the healthcare inequities that Black people continue to face. Representation in clinical trials that reflects and matches disease statistics among Black populations is key to the ultimate goal of improving health outcomes. Increasing Black research participation is contingent on the concerted efforts of investigators, trial sponsors, health care providers, patients, patient caregivers, patient advocacy groups, community groups, academic centers and industry partners.

Medical Mistrust

Medical mistrust is a major contributing factor to health disparities among Black communities in North America. A study published in the Journal of Health Care for the Poor and Underserved found that mistrust of healthcare systems was the primary barrier to participation in medical research among African American adults. This mistrust stems from both historic and continuing events in healthcare pertaining to issues of racial and socioeconomic discrimination.

During the COVID-19 pandemic, the inherent distrust many Black Americans hold for healthcare systems not only translated into lower rates of vaccination, but also greater reluctance in accessing and seeking medical care compared with other ethnic groups, and particularly with white counterparts.

Medical mistrust among Black Americans has developed over centuries of not just racial marginalization and segregation, but active medical abuse and exploitation.

Subjection to unethical, experimental trials like the infamous Tuskegee syphilis study conducted among Black men who were denied treatment for syphilis in order to test new drugs, and the 1920s “Mississippi Appendectomy” that involved the forced sterilization of poor Black women without their knowledge under the guise of appendectomies (as hysterectomy training for young doctors), continue to serve as a harrowing reminder of the relationship between Black people and America’s medical systems. Lack of transparency and consent were also at play in the case of Henrietta Lacks, an African American woman whose cervical tissues were taken without her knowledge when being treated for cervical cancer at Johns Hopkins in the early 1950s; her samples were used to develop the widely used HeLa cell line. Currently, members of Lacks’ family are fighting legal battles against companies like Thermo Fisher Scientific over commercial rights over the cells.

Past events still shape a large part of the medical experience for Black people in America. And with continued racial discrimination still rampant in US healthcare systems, along with significant barriers to access, that experience has not improved by a whole lot.

Race-Based Medicine

Ethnicity can be a significant medical determinant with respect to predisposition to certain diseases, tailored/personalized therapies and response to treatments.

However, the links between race-based genetics and disease are not quite clear. For example, although rates of asthma and asthma-related deaths are higher among Black people than white people, and Black men in the US are 50 percent more likely to develop lung cancer than white men,  71 percent of African-Americans and 58 percent of white Americans live in communities that violate federal air pollution standards. African-Americans are more likely to live near transportation hubs and places where the air is drawn.

However, there are some clearer instances of racial determinants of disease in conditions like sickle cell disease (SCD) and sickle cell trait (SCT), for example. In the US, SCD affects about 100,000 people. One in 365 Black or African American babies are born with SCD and one in 13 babies with SCT. SCD and SCT are more prevalent in African-origin populations due to a disease-causing mutation that is protective against severe forms of malaria, which is common in places like Africa.

Personalized Medicine

Targeted therapies are designed against specific disease-identifying/-causing molecular markers such as genetic mutations. These disease-associated markers may not only drive or help identify disease but may also help predict response to therapy.

Gene mutations and other molecular markers can be used to help stratify patients into different subgroups, and then tailor therapies based on their molecular and/or cellular tumor profile. This approach necessitates representation of a spectrum of populations in trials in order to identify subgroups harboring specific markers and mutations. This information is then used to personalize treatments as well as design new targeted therapies with the goal of administering those that work best for a given patient or patient population.

The exclusion of minority groups like Black people in trials can potentially preclude them from benefiting from innovative new treatments. A recent study showed that Black patients made up less than four percent of participants across several trials evaluating immune checkpoint inhibitors approved for the treatment of lung cancer. The underrepresentation of Black participants is particularly glaring in oncology trials. This is especially concerning as Black/African Americans have a 28 percent higher cancer-related mortality compared with white people.

In a recent webinar, Ricki Fairley, chief executive officer, TOUCH, The Black Breast Cancer Alliance, spoke about the underrepresentation of Black women in breast cancer trials. According to statistics presented in the presentation, while Black women account for 12 percent of new breast cancer cases in the US, they only comprised three percent of all participants in breast cancer clinical trials that supported FDA drug approvals between 2008 and 2018.

Moreover, despite having similar treatment outcomes as white people, Black men have a 40 percent, and Black women a 20 percent, higher cancer-associated mortality rate compared with white people. This highlights a need for both better trial and care access.

Barriers to Access for Black Trial Participation

There are multiple barriers that prevent active trial participation. These include cultural/language, educational and socioeconomic barriers, as well as poor outreach to Black communities, a lack of communication and engagement from researchers and primary healthcare providers on the importance of trial participation and lower numbers of Black medical professionals in healthcare among others.

Socioeconomic barriers can prevent people from accessing healthcare due to issues of not having paid time off for medical appointments and time and costs associated with transportation if clinics or trial sites are located at a significant distance from where they live.

In addition, discussing medical issues can be uncommon in some cultures. This may be due to stigma associated with sickness and disease, and a general lack of awareness and education on health topics. This holds true for many Black communities in America. For example, singer-songwriter Mary J. Blige has recently participated in campaigns to help increase awareness about the importance of early breast cancer screening for Black women as well as participation in clinical trials. She explained how cancer hit home for her after two of her family members were diagnosed with breast cancer. Prior to that, she said cancer was not a topic that was discussed in Black families like hers.

Due to systemic inequalities, which lead to an unwillingness to seek healthcare, Black patients disproportionately lose out on education from healthcare providers. However, the onus is not solely on the patient. Healthcare professionals also have the responsibility to inform and educate their patients. However, the Black racism that permeates healthcare systems, unfortunately, includes some providers in the systems who may not take the task of communicating and educating their Black patients seriously.

Many Black patients also have limited encounters with Black healthcare providers because white providers significantly outnumber them. People often feel more comfortable and can relate to a healthcare professional who is of the same background as them. Connecting Black patients with Black physicians and researchers through community outreach events can be a great way to disseminate information about clinical trials.

Steps and Solutions

Improving research participation among Black communities is one of the keys to helping eradicate healthcare disparities and ultimately, improving healthcare and health outcomes for Black patients.

There are several ways patients, investigators, trial sponsors, primary healthcare providers, patients, patient caregivers, patient advocacy groups and larger communities can help increase awareness about the importance of trial participation.

Community-level outreach is an effective way to begin conversations about research trials. A recent report published in The Lancet showed that adapting a grassroots level community engagement model involving partnerships between academic centers, communities, governments and industry partners could help bring information about research trials to people. As part of the model, the researchers partnered with a community health group for Black men and together, administered a community-facing webinar series and provided culturally sensitive educational materials on improving health equity through diversity, particularly by enhancing representation of racial and minority ethnic groups in clinical trials. The outreach reached over 250 people and included a diverse panel of speakers.

Utilizing different clinical trial models can also enhance trial participation. For example, hybrid and decentralized clinical trial (DCT) models were a success during the pandemic as they allowed for significant flexibility and accessibility. These factors are important to help improve access for trial participants that may not live near trial sites, as drugs and devices can be delivered to their homes and participants can be monitored through remote means. Educating potential Black trial participants about different trial models could help encourage greater participation.


Engaging people on the importance of increasing Black representation in clinical trials must begin with communication. The communication must be multi-directional, with patients having access to information from all sources involved, including investigators, patient advocacy groups, healthcare providers, industry (pharmaceutical/biotechnology/medical device) partners and community members and leaders. Through partnerships between these groups, information campaigns and community outreach programs can be effectively administered to help inform and educate Black communities on trial participation and the importance of clinical trial diversity.

Medical and scientific communities must gain the medical trust of Black communities to help increase Black trial participation. Fostering inclusive communication, acknowledging past traumas and eradicating systemic discrimination are key to paving the path forward in increasing clinical trial representation.