Black Americans Underrepresented In Clinical Trials Of Cardiovascular Drugs

Black U.S. residents have been significantly underrepresented in pivotal clinical trials of 24 cardiovascular drugs that received Food and Drug Administration (FDA) approval during the last 15 years, according to two researchers in China.

The underrepresentation could undermine the generalizability of the trials and the use of new cardiovascular drugs in Black Americans, they write in JAMA Network Open.

"In the United States, structural racism remains a fundamental cause of persistent health disparities," said Dr. Jiarui Li of Peking Union Medical College Hospital in Beijing, who did the analysis with colleague Dr. Siliang Chen.

"Given differences in pathophysiology, clinical presentation, and outcomes of cardiovascular disease in different racial groups, adequate participation is important to allow examination of possible racial differences in treatment response," he told Reuters Health by email.

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Drs. Li and Chen conducted a cross-sectional study of 24 new cardiovascular drugs approved by the FDA between 2006 and 2020. The drugs were approved for several cardiovascular conditions in the U.S., including hypertension, coronary-artery disease, acute coronary syndrome, myocardial infarction, heart failure, atrial fibrillation, pulmonary arterial hypertension and hypercholesterolemia.

The researchers analyzed participation data for the trials from the Drugs@FDA database and evaluated the representation of Black and white U.S. residents in the trials by calculating participation-to-prevalence ratios. They also looked at participation based on each cardiovascular condition in the U.S. A ratio between 0.8 and 1.2 indicates that the trial represented the overall population. Ratios below 0.8 indicate underrepresentation, and ratios above 1.2 indicate overrepresentation.

Overall, the trials enrolled more than 187,000 participants, including 5,396 Black participants and 155,694 white participants. For Black residents, the percentage of clinical-trial participation was 2.9%, and the total participation-to-prevalence ratio for all cardiovascular conditions was 0.29, indicating a significant underrepresentation.

The highest ratio for Black participants was 0.52 for hypertension, and the lowest was .072 for hypercholesterolemia. All ratios were less than 0.8 for Black residents.

However, for white residents, the percentage of clinical-trial participation was 83.1%, and the total participation-to-prevalence ratio was 1.14. The highest ratio for white participants was 2.77 for hypercholesterolemia, and the lowest was 0.88 for pulmonary arterial hypertension. All ratios were greater than 0.8 for white residents.

In addition, the ratios of white participants were higher than 1.2 for acute coronary syndrome, myocardial infarction, coronary-artery disease, heart failure, hypertension and hypercholesterolemia, indicating overrepresentation. The breakdown of ratios by year also showed underrepresentation of Black U.S. residents.

"Although the National Institutes of Health established the Revitalization Act in 1993 to ensure that racial minority groups are adequately enrolled in clinical trials, the enrollment of Black U.S. participants in cardiovascular trials was still disappointing," Dr. Li said. "Significant racial disparities have persisted over the past 15 years."

The Revitalization Act provided additional funds to increase recruitment of Black participants, launched the FDA Office of Minority Health and Health Equity in 2010, established the FDA Drug Trials Snapshots and mandated race and ethnicity analyses in phase-3 clinical trials, the authors note. However, these measures may not have helped due to possible implicit biases, disparities in socioeconomic status and unique cultural practices, they say.

More effective strategies are needed to increase the enrollment of racial minority participants in clinical trials, particularly Black residents in the U.S., according to the authors.

"Different demographic subgroups can have a contrasting effect on drug responses, so it is important to enroll a representative sample," said Dr. Shahzeb Khan of the University of Mississippi Medical Center in Jackson. Dr. Khan, who wasn't involved with this study, has researched trends in clinical trial enrollment of minority groups and women in FDA-approved cardiometabolic drugs.

"There has been inadequate representation of Blacks in clinical trials of cardiovascular drugs," he told Reuters Health by email. "Strong efforts are needed to enhance enrollment of ethnic minorities in clinical trials so we can gauge any variation in drug therapies."

—Carolyn Crist

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