Achieving Diversity in Clinical Research: A Continuing Challenge for Sponsors, Investigators and Communities

By Dr. Luther T. Clark, MD, FACC, FACP, Deputy Chief Patient Officer, Patient Innovation & Engagement, Merck

The COVID-19 pandemic and recent demonstrations for social justice across the U.S. have put a spotlight on systemic racism, health care disparities, and the imperative to achieve health equity.  


Clinical trials generate the evidence necessary for evaluating the safety and efficacy of new medicines and medical products. When the clinical trial population reflects the characteristics of the population for whom treatment is intended, those individuals who subsequently use the medicines are better served and we advance better health outcomes. Clinical trial participation also provides access to new and innovative treatment options for patients, an especially important benefit for those who have conditions with limited treatment options – such as some forms of advanced cancer.

Cancer is a particularly powerful example of how longstanding inequities in care coupled with the pandemic’s impact on reduced access/utilization of routine health care can converge and create an even more devastating impact on patients, families, and communities. Cancer incidence is known to be disproportionately higher in under-represented minorities compared to other groups, and access – to timely diagnosis, quality care, and to clinical trials of promising therapies – is suboptimal among people of color. Furthermore, cancer and its treatment predispose to many other health outcome disparities, as demonstrated by the disproportionate impact of COVID-19 on morbidity and mortality rates among people with cancer.

Barriers to Clinical Trial Participation

The major barriers to participation of racially and ethnically underrepresented patients in clinical trials include: (1) mistrust, (2) fear, (3) lack of comfort with the clinical trial process, (4) lack of information about clinical trials, (5) logistical constraints associated with participation such as time and out-of-pocket expenses, and (6) the impacts of social determinants of health. In addition, there is a shortage of suitably qualified investigators and a lack of infrastructure & resources needed to perform clinical trials in underrepresented communities and populations.


Mistrust of research and the fear of being a “guinea pig” are among the most significant barriers to clinical trial participation for underrepresented groups. While the ultimate decision regarding clinical trial participation rests with the patient, that decision may be influenced by family, close friends, and other trusted individuals and groups in their own communities. Therefore, building trust between researchers and trusted community stakeholders (faith-based organizations, nonprofit and civic groups, community leaders, patient advocacy groups, community health care providers, etc.) is critical for improving participant diversity.

Social Determinants of Health (SDOH)

Social and economic factors, referred to as social determinants of health (i.e., education, economic stability, neighborhood, health and health care access, social and community context) not only contribute to health care disparities but may also negatively impact the willingness and the ability of patients to participate in clinical research. By recognizing and understanding the SDOH, we can help overcome barriers to minority participation in research and ultimately improve patient outcomes.

Overcoming Barriers and Achieving Diversity in Clinical Research: The Power of Patient and Community Engagement

Meaningful patient and community engagement can help achieve diversity as well as advance both science and patient care. In addition to helping empower patients to be more active participants in their medical care, appropriate and meaningful engagement between trusted community stakeholders (participants, patients, caregivers, patient advocacy organizations, and leaders) and researchers (clinical trial sponsors, investigators, clinical research sites) can help effectively address the perspectives and priorities that are important for patients — those who will be impacted by the research.

In order to gain insights about what matters to patients and their communities, we engage with patients and their advocates through activities such as patient advisory panels and expert input consultations. Effective and meaningful community engagement should be long-term rather than based solely on specific trial or project needs.


In summary, increasing research participant diversity continues to be a challenge for sponsors, investigators, and communities. However, the COVID-19 pandemic and community unrest due to racial injustice and inequities — that have amplified disparities, the impact of health inequities, and the importance of impacted communities’ participation in research and development of health care solutions — provide an opportunity to make real and sustainable progress toward achieving diversity and inclusion in clinical research as well as improving health care access and outcomes for all communities.