Representation in Clinical Trials: A Review on Reaching Underrepresented Populations in Research

Clinical Researcher—August 2020 (Volume 34, Issue 7)


Isabelle Yates; Jennifer Byrne; Susan Donahue, CCRC, ACRP-PM; Linda McCarty, JD; Allison Mathews


In a recent report from the U.S. Food and Drug Administration (FDA) on its 2018 Drug Trial Snapshots, there is a significant imbalance in representation of minorities in clinical research. Whites make up 67% of the U.S. population, but are 83% of research participants.[1} Black/African Americans make up 13.4% of the U.S. population, but only 5% of trial participants. Hispanic/Latinos represent 18.1% of the U.S. population, but less than 1% of trial participants.{2}

Further, a recent examination of the topic found that, of the 5,157 patients who participated in oncology trials, 38% were women, 68% were White/European American, 15% were Asian American, 4% were Black/African American, 4% were Hispanic/Latino, 50% were 65 years and older, and only 38% were residing in the U.S.{3} Even with attempts to regulate and include participants from more ethnic backgrounds in studies, 48% of the adult trials did not meet the target recruitment goal for including underrepresented populations (i.e., Black/African Americans, Hispanics/Latinos, Asian Americans, and other populations with different ethnic backgrounds).{4}

Participants in clinical trials should reflect the diversity of the population, with particular attention to those most affected by the disease. A lack of representation from racial/ethnic minority groups in clinical trials has resulted in the development of interventions that have not translated well into real-world use and have not been efficacious in different populations.

For example, 5-Fluorouracil, a commonly used cancer chemotherapeutic drug, has been frequently reported to exhibit differences in drug response among different populations.{5} A major side effect associated with this fluoropyrimidine-based drug is the occurrence of hematologic toxicities, including leukopenia and anemia. These toxicities are often found to occur in higher rates in underrepresented populations than White/European Americans. However, the clinical trials conducted to test the drug were overrepresented with White/European American participants; thereby, missing the opportunity to assess the adverse side effects in racial/ethnic minority groups.

Differences in lived experiences, opportunity, and exposure to environmental stressors and toxins among racial/ethnic groups can be missed when clinical trials fail to test interventions on diverse participants. The purpose of this article is to highlight the top five major challenges facing populations who are underrepresented in research, and to identify several strategies to promote diversity in participation.


Challenge 1: Low Income as a Barrier to Participation

The first challenge is income. In a prospective survey study conducted in 2016, patients with household annual incomes below $50,000 were 27% less likely to participate in clinical trials, and as income dropped, so did the likelihood of trial participation.{6}

As explained by the FDA, ethnic minority groups are affected more by poverty and lower socioeconomic status and, in turn, this leads to poorer health in their communities.{7} Due to lower socioeconomic status, many members of these ethnic minority communities receive hourly wages, which makes it difficult for them to find the time to fit trial participation into their weekly schedule.

Challenge 2: Investigator Bias

The second challenge is bias. Sponsors often have to rely on healthcare professionals to tell their patients about a clinical trial. Unfortunately, healthcare professionals also hold their own biases that sometimes interfere with enrolling racial/ethnic minorities in studies.

For example, healthcare professionals have been shown to withhold treatments based on preconceived notions about whether the racial/ethnic minority patient would adhere to the protocol.{8} Many potential participants never receive information about a possible study due to these biases exacerbating enrollment gaps in studies.

Additionally, racial/ethnic minorities are more likely to trust a provider from a background similar to their own. The race of the physician often influences the racial makeup of the clinical trial volunteers they most successfully inspire toward participation. Given the lack of adequate representation of medical providers and investigators from racial/ethnic minority groups, few minority patients are likely to enroll in clinical trials.{9}

Further, it is an unfortunate trend that minority investigators tend to conduct and initiate fewer clinical trials annually. Minority investigators tend to be younger and have limited clinical research infrastructure and less support than their White colleagues.{9}

Challenge 3: Medical Mistrust

The third challenge is mistrust. In one study, researchers gathered responses from 527 Black/African American patients and 382 White/European American patients regarding their levels of trust in doctors. The study showed that Black patients were less likely to trust their doctor to explain how they would participate in research. They also do not trust that they will not be exposed to unnecessary risks.{7}

These perceptions of mistrust were not totally unfounded. There has been a long history of medical and scientific exploitation that has targeted and adversely affected Black/African American people. The lack of trust between racial/ethnic minorities and their providers is often associated with a perception that they are asked to take on most of the risks associated with medical research.{7}

Despite these challenges, Black community members have shown more willingness to participate in prevention and wellness studies than drug trials, and there is some evidence showing willingness to participate in studies involving blood draws and other medical procedures.{10}

Challenge 4: Limited Health and Research Literacy

The fourth challenge is health and research literacy. Many racial/ethnic minority populations have less access to updated information about health conditions and research, thereby limiting their understanding of the symptoms of disease or the clinical research process. Due to lack of

medical and health information, many racial/ethnic minorities may delay seeking treatment from professionals or misunderstand the appropriate circumstances under which it is important to seek treatment. They may also know little about which treatment options are available to them, including clinical research and trials as care options.{7}

Challenge 5: Lack of Access to Transportation

A fifth challenge is transportation. Many minorities do not live in areas with easily accessible care. This requires them to travel farther than others and makes them less likely to participate in research or seek out care options in general.


Despite the challenges we have described, there are multiple strategies available to promote diversity in clinical trial participation.

Strategy 1: Promote Culturally Competent Communication and Transparency

The most important strategic goal involves addressing mistrust through communication and transparency. Communicating in a way that is culturally relevant to the population being engaged with has been shown to promote trust.

Roman Isler, et al. developed a culturally responsive research literacy curricula that educates community members about the importance of participating in clinical research.{11} Others are making efforts to ensure that research materials (i.e., recruitment materials, informed consent documents, study results, etc.) are designed in ways that promote clear understanding of the research questions, study design, participant protections, and potential community benefit.{12}

Communication should also promote transparency and addressing community concerns. By addressing racial/ethnical minority community members’ concerns about the trial early, they are more willing to participate and to trust the provider. It is also key to reiterate the benefits to them of participating in clinical trials and research; these include gaining access to expert medical care, learning more about their condition, and playing an active role in their own personal healthcare.{13}

Strategy 2: Provide Financial Support and Supportive Services to Promote Participation

To address income-related challenges, it is important to provide adequate participant compensation that also addresses healthcare needs post-participation. Many participants avoid participation because of concerns regarding insurance companies denying coverage for conditions that develop after clinical trial participation.{14} It is important for investigators to consider how adverse side effects would be addressed for participants post-study.

Additionally, investigators could consider providing caregiving support for those who otherwise could not participate due to work or family obligations. Alternative strategies including offering a home visit option for those who might not be able to leave their home and extended office hours for those who have work conflicts.

When longer site hours and home visits are options, they allow for the participant to come to the trial site at a convenient time after work or can lift the burden of finding and paying a sitter. Home visits are the best options for many geographically isolated patients to not have an added burden of finding transportation to and from the trial location.

Strategy 3: Provide Transportation Support

To address transportation challenges related to geographic isolation from healthcare resources, researchers can provide transportation, subsidize gas and parking fees, or provide options for telemedicine using mobile technology. Telemedicine and mobile technology allow the patient to remotely connect with their provider and not have to take a large amount of time out of their day to receive care and/or participate in a trial.{1} Providing transportation assistance allows the participant to reach the trial site more easily and to worry less about the cost and impact on their schedule.


By building a bridge between research and participants, we can reach more racial/ethnic groups and provide better health interventions to those who need it the most.


  1. Deloitte. 2020. Why Improving Inclusion and Diversity in Clinical Trials Should be a Research Priority.
  2. Clinical Research Pathways. 2020. Diversity in Clinical Trials.
  3. American Society of Clinical Oncology. 2020. Enrollment of Racial Minorities in Clinical Trials: Old Problem Assumes New Urgency in the Age of Immunotherapy.
  4. Mak WWS, et al. 2007. Gender and Ethnic Diversity in NIMH-Funded Clinical Trials: Review of a Decade of Published Research. Administration and Policy in Mental Health and Mental Health Services Research 34(6):497–503. doi:10.1007/s10488-007-0133-z
  5. Bachtiar M, Lee CGL. 2013. Genetics of Population Differences in Drug Response. Current Genetic Medicine Reports 1(3):162–70. doi:10.1007/s40142-013-0017-3
  6. Unger JM, et al. 2016. Patient Income Level and Cancer Clinical Trial Participation. JAMA Oncology 2(1):137. doi:10.1001/jamaoncol.2015.3924
  7. Diversity in Clinical Trial Enrollment: Exploring the Roadblocks to Minority Participation in Clinical Research. 2019.
  8. FitzGerald C, Hurst S. 2017. Implicit Bias in Healthcare Professionals: A Systematic Review. BMC Medical Ethics 18(1). doi:10.1186/s12910-017-0179-8
  9. Getz K, Faden L. 2008. Racial Disparities Among Clinical Research Investigators. American Journal of Therapeutics 15(1):3–11. doi:10.1097/mjt.0b013e31815fa75a
  10. Byrd GS, et al. 2011. Recruiting Intergenerational African American Males for Biomedical Research Studies: A Major Research Challenge. Journal of the National Medical Association 103(6):480–7. doi:10.1016/s0027-9684(15)30361-8
  11. Isler MR, et al. 2014. Curriculum Development to Increase Minority Research Literacy for HIV Prevention Research: A CBPR Approach. Progress in Community Health Partnerships: Research, Education, and Action 8(4):511–21. doi:10.1353/cpr.2014.0059
  12. Day S, et al. 2020. Broadening Community Engagement in Clinical Research: Designing and Assessing a Pilot Crowdsourcing Project to Obtain Community Feedback on an HIV Clinical Trial. Clinical Trials 17(3):306–13. doi:10.1177/1740774520902741
  13. Forte Research. 2016. Top 4 Barriers to Patient Participation in Clinical Trials.
  14. George S, et al. 2014. A Systematic Review of Barriers and Facilitators to Minority Research Participation Among African Americans, Latinos, Asian Americans, and Pacific Islanders. American Journal of Public Health 104(2):e16–31. doi:10.2105/ajph.2013.301706

Authors’ Note

At Javara, we recognize the importance of building the next generation of clinical research professionals and are committed to fostering growth in our interns by providing hands-on experiences. There is a need for organizations to create opportunities for the clinical research professionals of the future—in the U.S. alone, there are more than 44,000 jobs related to clinical research available.

Javara is deeply committed to the advancement of clinical research with workforce innovation aimed at growing the future leaders of our industry and promoting clinical trial awareness, education, and training through our summer internship programs. We also provide our students with the tools and experiences needed to promote clinical research as a care option by offering corporate and clinical internships with opportunities spanning the realms of study start-up, trial activation, patient engagement, recruitment, communications, legal issues, direct patient care, and more.

Isabelle Yates developed this review during a student internship at Javara Inc., an integrated research organization in Winston-Salem, N.C., where she also assisted with a Phase III COVID-19 vaccine trial and a community partnership research study with Wake Forest Baptist Health. She is a biological engineering major at Purdue University.

Jennifer Byrne is CEO of Javara Inc., founder of Greater Gift, and a member of the Association Board of Trustees for ACRP.

Susan Donahue, CCRC, ACRP-PM, is Senior Director of Operational Excellence at Javara Inc.

Linda McCarty, JD, is Co-founder, General Counsel, and Privacy Officer at Javara Inc.

Allison Mathews is the Integrating Special Populations Associate Director for Wake Forest Baptist Health’s Maya Angelou Center for Health Equity in Winston-Salem, N.C.