U.S. heart transplant clinical trials demonstrate persistent and clinically meaningful inequities in sex, racial, and ethnic representation, which may compromise the external validity of trial findings and perpetuate disparities in transplant care.
Key Findings
Methods
The analysis included 27 eligible U.S. heart transplant trials with publicly available results, enrolling 2,271 participants in total.
Cross-sectional analysis of U.S.-based HT trials registered on ClinicalTrials.gov between 2000 and 2025.
Demographic data on sex, race, and ethnicity were independently extracted and categorized using federal reporting standards.
Enrollment was compared with 2010 and 2020 U.S. Census data and with overall HT recipient data.
Proportions were estimated with Wilson 95% CIs; racial distributions used multinomial CIs with Bonferroni adjustment.
Results
Women were underrepresented in U.S. heart transplant trials at 24.2% of participants.
Female representation was 24.2% (95% CI: 22.5%-26.0%).
This was below U.S. population benchmarks (~50%).
It was also below HT recipient proportions (27.0% in 2010; 28.4% in 2020).
Results
White participants were overrepresented in trials relative to both the U.S. population and HT recipients.
White participants made up 75.3% of trial enrollment.
This compares with 61.6% in the 2020 U.S. population and 59.3% of HT recipients.
Results
Black participants were underrepresented in trials relative to the HT recipient population.
Black participants comprised 15.5% (95% CI: 12.2%-19.5%) of trial enrollment.
This was lower than the HT population proportion (25.0% in 2020).
Results
Hispanic/Latino and Asian participants were markedly underrepresented relative to national population proportions.
Hispanic/Latino participants were 9.7% of enrollment versus 18.7% nationally.
Asian participants were 1.7% of enrollment versus 6.0% nationally.
Results
Multiracial and Indigenous/Pacific Islander participants were nearly or completely absent from trials.
Multiracial participants comprised 0.3% of enrollment.
Indigenous and Pacific Islander participants comprised 0%.
Results
Reporting of race and ethnicity improved over time, with universal reporting in trials conducted after 2020.
Reporting completeness increased across the 2000–2025 study window.
All trials conducted after 2020 reported race and ethnicity data.
Conclusions
The authors conclude that the representation gaps may compromise external validity and perpetuate disparities, and call for standardized reporting and equity-focused enrollment.
Recommendations include standardizing demographic reporting and implementing equity-focused enrollment strategies.
Authors advocate aligning trial populations with evolving demographics of advanced heart failure.
What This Means
This study looked at 27 U.S. heart transplant clinical trials, with a combined 2,271 participants, registered on ClinicalTrials.gov between 2000 and 2025. The researchers compared who was enrolled in these trials with the make-up of the U.S. population and with people who actually receive heart transplants.
The trials enrolled fewer women (24.2%) than are found in the general population (about half) or among heart transplant recipients (about 27–28%). White participants made up about three-quarters of trial participants, more than their share of the U.S. population or of transplant recipients. Black, Hispanic/Latino, and Asian participants were underrepresented, and multiracial, Indigenous, and Pacific Islander people were almost entirely missing. On the positive side, reporting of race and ethnicity has improved, and all trials after 2020 reported it.
This research suggests that the evidence used to guide heart transplant care may not fully reflect the patients who receive transplants, which could limit how well findings apply to women and to many racial and ethnic groups. The authors call for better demographic reporting and enrollment strategies aimed at making trial participants more representative. This was an analysis of trial enrollment only and does not itself show how outcomes differ between groups.
Manasrah A, Sporn K, Manasrah S, Lee R, Maxey-Jones C. (2026). Equity Gaps in Sex, Racial, and Ethnic Inclusion in United States Heart Transplant Trials.. Clinical transplantation. https://doi.org/10.1111/ctr.70726