Throughout the history of medical studies, trial participants have been overwhelmingly white — a situation that has long led to skewed results and diverging health outcomes in the U.S.
During the pandemic, these disparities were thrust into the spotlight as Black, Hispanic, and other ethnic and racial groups experienced higher rates of COVID-19 cases and deaths compared to white people. Yet, these groups were still underrepresented in vaccine trials for the virus.
The Kaiser Family Foundation reports that although white people make up about 73.6% of the U.S. population, they accounted for 81.9% of participants in the Pfizer-BioNTech vaccine trials and 79.4% in the Moderna trials.
Conversely, 12.3% of the U.S. population is Black, but Black people made up only 9.8% and 9.7% of participants in the Pfizer-BioNTech and Moderna trials, respectively.
However, there are many nuances within these statistics, according to a report from the IQVIA Institute for Human Data Science.
For example, the report shows that although clinical trials generally have a disproportionate number of white participants, Black/African American and Hispanic patients are over-represented in phase 1 studies compared to the overall population.
The report authors point to a range of possible factors to explain the discrepancy — including socio-economic drivers such as higher payments for participants in phase 1 trials and the locations where the trials are conducted.
The report also shows that despite the recent attention on clinical trial diversity, it has actually decreased — not increased — over the past decade among Black/African American participants. After hitting a peak of 12.3% in 2013, the Black participation rate has declined consistently over the last decade. Between 2020 and 2021 the rate fell from 9.8% to 6.5%.
While the numbers look grim, the authors note that this apparent drop may actually have more to do with an improvement in participation reporting — rather than a decrease in participation. Either way, the main takeaway remains: Clinical trial participation often doesn’t reflect the country’s patient population.
Enrollment discrepancies
In addition to differences between phase 1 and later-stage participation, the report also shows different levels of diversity by therapeutic area. In some phase 2 and 3 trials completed in 2020 in hematology, infectious diseases and psychiatry, Black patients were overrepresented compared to U.S. demographics. Conversely, Black patients represented less than 5% of the enrollment in allergy, oncology and respiratory trials.
More Hispanic patients participated in hepatology, endocrinology and infectious disease trials compared to other U.S. demographic groups, but were significantly underrepresented elsewhere.
In April, the FDA issued draft guidance for drug developers to create concrete plans to enroll more trial participants from underrepresented racial and ethnic populations. The guidance recommends that trial sponsors develop and submit a Race and Ethnicity Diversity Plan to the FDA early in clinical development, based on a framework outlined in the guidance.
“They will be expected not only to understand potential equity barriers but to explain what they’re doing to overcome them for their product in development,” Aman Khera, the global head of regulatory strategy at Worldwide Clinical Trials, told PharmaVoice last year.
According to the FDA, many factors affect lower participation among minority patients, such as mistrust based on past abuses, which often stem from incidences like the Tuskegee syphilis study that enrolled Black men who were not informed about the nature of the research and were intentionally not treated for their syphilis. The study resulted in the death of more than 100 participants.
Other barriers include issues like lack of transportation, limited healthcare access and literacy, and location and time constraints.
In addition to guidance from the FDA, Congress is also attempting to act. Tucked within its omnibus spending legislation is a provision to require drug and device sponsors to submit diversity action plans, which echoes the FDA guidance, JD Supra reports.
In the meantime, though, the IQVIA Institute report authors write that researchers have “significant opportunities” to improve diversity through concrete plans, clear goals, and measuring results using transparent metrics.
