Study Finds Diversity in Clinical Trials Still Lacking

Racial and ethnic diversity in clinical trials is lacking despite FDA recommendations regarding demographic characteristics of specific study populations, according to a recent JAMA Network Open study.

Researchers used data from completed interventional vaccine trials from July 2011 to June 2020. To be included in the study, trials had to be categorized as completed and have available results. 

In total, 230 US-based clinical trials with a total of 219,555 participants met the criteria for inclusion. The trials represented in the study were randomized, included viral vaccinations (69.1 percent), and represented all trial phases. Every trial also reported age and sex. 

Overall, white individuals were overrepresented (77.9 percent of the time) in clinical trials. 

In the same trials, Black or African American individuals were represented only 10.6 percent of the time and Hispanic or Latino participants were represented just 11.6 percent of the time. 

Additionally, in pediatric trials, Black or African American participants were represented just over 10 percent of the time and Hispanic or Latino participants were represented 22.5 percent of the time. 

Asian individuals and American Indian or Alaska Native individuals were represented the least amount in the trials, at just 5.7 percent and 0.4 percent, respectively. 

Among trials reporting race or ethnicity, 65 (48.5 percent) did not include American Indian or Alaska Native participants and 81 (60.4 percent) did not include Hawaiian or Pacific Islander participants.

For recruitment, 178 clinical trials recruited adults and 52 recruited only children. Of the trials including adults, 80 (45 percent) were 65 years of age or older and 71 (39.9 percent) enrolled trial participants 65 years or older. Five trials recruited only older adults.

Out of the 170 studies reporting age as a percentage, 12.1 percent of participants were 65 years of age or older compared to 16 percent of the 2018 US population representing this age group, researchers stated.  

Overall, the cross-sectional study found that among US-based vaccine clinical trials, members of racial or ethnic minority groups and older adults were underrepresented, whereas female adults were overrepresented.

According to researchers, these findings suggest that diversity enrollment targets should be included for all vaccine trials targeting epidemiologically important infections. 

In 2000, the NIH updated its Revitalization Act, a policy for the inclusion of women and minority groups in clinical trials. The updates required inclusion of women and members of minority groups in all “biomedical and behavioral research projects involving human subjects.”

Then in 2017, another update required investigators to not only include the specified groups in NIH-defined Phase 3 clinical trials, but also submit their results to ClinicalTrials.gov after conducting analyses based on sex, gender, and race or ethnicity, researchers explained.

But despite these advancements, equity in clinical trial diversity remains an issue. 

Researchers noted a report that found that less than two percent of clinical trials studied over a two-year period had minorities as the primary focus and that the percentage of manuscripts reporting race and ethnicity data ranged from 1.5 percent to 58 percent. 

Improving diversity in clinical trials is important because enrollment may be associated with vaccination rates in minority groups, researchers stated. 

Additional inclusivity may also help to address vaccine hesitancy, provide education, and enhance safety concerns about vaccines. 

“Our study contributes additional data to the reported gaps in participant representation; although of importance, the gaps were not large in general. Our study showed that diversity and inclusion challenges remained among vaccine trials because many trials enrolled participants while these updated regulations were already in place,” researchers said in the study. 

“Successful inclusion of underrepresented groups in COVID-19 vaccine trials should help guide future trials,” they concluded.