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How to reach underrepresented populations in research

A recent article, reported in Clinical Researcher on the ACRP website, discusses issues with engaging underrepresented populations in research and has identified strategies to promote diversity in participation.

Underrepresented populations

Increasing evidence is emerging which reports the significant imbalance in representation of minorities in clinical research. For example, in the US, White individuals make up 67% of the population but are 83% of research participants. Whereas Black/African Americans make up 13.4% of the population but make up only 5% of trial participants. Hispanic/Latinos also represent 18.1% of the US population yet represent less than 1% of trial participants. A recent report emphasised this disparity as it outlined that a third of COVID-19 studies did not report race or ethnicity data. The report also discussed that there was a significant underrepresentation of black patients in all studies.

With the ongoing pandemic, it is now, more than ever, important to ensure that diverse populations are represented in research and clinical trials. Lack of representation from minority groups in clinical trials impacts the ability to translate findings and inferences into real-world use. For example, researchers have reported that a commonly-used chemotherapy drug, 5-Fluorouracil, shows differences in drug response among different ethnic populations. As the initial clinical trials were overrepresented with White/European American participants, there was a missed opportunity to detect adverse side effects in racial/ethnic minority groups.

In this article, authors highlight the top challenges facing populations who are underrepresented in research. It also identifies several strategies that aim to promote diversity in participation.


The authors report of five key challenges that underrepresented populations face, summarised below:

  1. Low income as a barrier to participation: In a survey conducted in 2016, patients whose annual household income was less than $50,000 were 27% less likely to participate in clinical trials. The survey reported that as income dropped, the likelihood of trial participation also dropped. Poverty and lower socioeconomic status often impacts ethnic minorities more. As a result, this leads to poorer health in these communities. Many communities receive hourly wages, which makes it difficult for them to find the time to fit trial participation into their lives.
  2. Investigator bias: Sponsors often rely on healthcare professionals to inform their patients about clinical trials. However, healthcare professionals can sometimes hold their own biases that impact the enrolment of racial/ethnic minorities in studies. For example, studies have shown that some healthcare professionals withhold treatments based on the judgement that racial/ethnic minority patients would not adhere to the protocol. Most racial/ethnic minorities trust providers that are from a similar background to theirs. However, representation of racial/ethnic minority medical providers is inadequate. Furthermore, minority investigators tend to conduct fewer clinical trials annually.
  3. Medical mistrust: In a study, compared to White/European American patients, Black patients were less likely to trust their doctor. They reported uncertainty about being exposed to unnecessary risks. This mistrust is the result of a long history of exploitation that has negatively impacted Black/African American individuals. Other studies have shown that Black community members are more willing to participate in prevention and wellness studies than in drug trials.
  4. Limited health and research literacy: Many minority populations have less access to updated health and research information. Therefore, their understanding of symptoms of disease or clinical processes is poor. In turn, many minority populations may delay seeking treatment or misunderstand when it is important to seek treatment.
  5. Lack of access to transportation: Many ethnic/racial minorities do not live in areas that are easily accessible to care. As a result, they often have to travel further which makes them less likely to participate or seek out general care.


The authors address these challenges and suggest multiple strategies that could help promote diversity in clinical trials, summarised below:

  1. Promote culturally competent communication and transparency: It is important to communicate in a way that is culturally relevant to different populations. This includes tailoring research material, i.e. consent forms and recruitment materials. This will ensure that researchers promote clearer understanding of the research questions, participant protections and potential community benefit. Communication must be transparent and must address community concerns. If researchers address concerns early, then people are more likely to be willing to participate and to trust the provider. It is important to reiterate the benefits of participation.
  2. Provide financial support and supportive services to promote participation: It is important to provide adequate participant compensation. The team note that this includes healthcare needs post-participation. Consideration of providing support for caregivers who otherwise would not be able to participate due to work or family obligations is important. An alternative option would be offering home visits.
  3. Provide transportation support: Researchers should provide transportation, subsidised petrol and parking fees or provide options for telemedicine using mobile technology. The latter option would allow patients to remotely connect with their provider and not take up a large amount of their day. Moreover, providing transportation assistance would allow participants to reach the trial site more easily without worrying about the cost.


Individual variation can result in different responses to the same drug. As a result, the diversity of clinical trial populations is critical for public health and well-being. Bridging gaps between research and participants is critical to ensure that all populations are represented within clinical trials. Researchers must ensure that they communicate transparently and clearly and listen to the concerns of others. Only by building an open dialogue and sense of community can we ensure that benefits of research can be seen for all.

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