Introduction: Liver transplantation (LT) is a critical therapeutic option for patients with end-stage liver disease, yet there are concerns about equitable representation amongst female patients and ethnic and racial minority groups in the United States. This study aims to assess their participation in US-based clinical trials for LT.

Methods: We used data from completed US liver transplant clinical trials registered and reported on the NIH website (clincaltrials.gov). Demographic data, including race, ethnicity, sex, and age were collected. SPSS, version 27.0 (IBM), and R, version 4.3.1 were used for statistics. To make inferences from our study to a larger population, we computed 95% confidence intervals (CIs) for estimates in each demographic group using the Wilson method for binomial proportions. We also computed the simultaneous 95% CIs by applying a Bonferroni correction to reflect the multinomial distribution of race proportions.

Results: 69 US-based clinical trials with 6,990 participants were included. While NIH funded only 13% of these trials, universities and organizations in the US were the most funding source (57%). Compared to their representation in the US population, Asians were over-represented at 9.3% [95% CI: 8.1%-10.5%], while Blacks (7.8%; 95% CI, 6.7%-8.9%) and American Indians (0.4%; 95% CI, 0.1%-0.6%) were underrepresented (Table 1). White participants appeared to be equally represented to the general US population (75.9%; 95% CI, 74.1%-77.7%). For ethnicity, Hispanics (13.3%; 95% CI, 12.2%-14.5%) were underrepresented independent of the census year (Figure 1-A). Among the 41 trials reporting data on race, only 7 (10%) trials included American Indians, and 7 (10%) had Native Hawaiian and Pacific Islander participants. Conversely, 100% of trials included White participants.
In industry-funded trials, Asian participants (15%) were overrepresented threefold compared to their representation in the US population. In NIH-funded trials, White (83.8%) participants were overrepresented, and Black (4.1%) participants were underrepresented compared to the general US population (Figure 1-B). Overall, women were underrepresented (31.1%; 95% CI, 30.0%-32.2%) compared to the general US population.

Conclusion: This study uncovers significant underrepresentation of certain racial and ethnic minorities and women in US LT clinical trials. Implementing explicit diversity enrollment targets is recommended to address these disparities. It is imperative that medical, surgical, and community leaders undertake tangible actions to improve recruitment strategies and foster community outreach programs to ensure equitable participation in LT research.

<b>Table 1. </b>Racial/ethnic and gender inclusion in liver transplantation clinical trials in the United States

Table 1. Racial/ethnic and gender inclusion in liver transplantation clinical trials in the United States

Figure 1: Racial/ethnic and gender inclusion in liver transplantation clinical trials according to (A) year of study and (B) funding source.

John Helzberg

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