Inequities in Organ Transplant Allocation

Elsa Kinney is a biology and public health major and she is a 2024-25 health care ethics intern at the Markkula Center for Applied Ethics at Santa Clara University. Views are her own.

Geographical Barriers: Hawai’i Gets the Short End of the Stick

Being from Hawai’i, I’ve seen firsthand how geographic location contributes to inequities in the organ transplant system. For example, over the past eight years, 604 kidneys were donated locally in Hawai’i, but 40% of them were sent to the mainland. In contrast, Hawai’i received only five kidneys in return. This imbalance sparked my interest in the disparities within the organ transplant system to explore what other inequities exist. To my surprise, there were various issues in both the policies and practices of the donation and reception systems that disproportionately affected minority communities across the United States.

Who’s in Charge of Organ Transplants?

In the United States (US), there are currently over 100,000 people on various organ transplant waiting lists. Nearly 60% of people on transplant waiting lists come from minority communities, while about 30% of donors are people of color. These numbers do not even account for patients waiting to be added to the organ transplant list or eligible candidates unaware that they qualify–many of which are disproportionately racial, ethnic, and gender minorities. There are significant disparities in the U.S. organ transplant system related to both racial and gender factors. This is largely due to implicit biases in referrals for transplant waiting lists and the criteria used to select candidates to receive organs. 

Since 1986, the United Network for Organ Sharing (UNOS) has single-handedly overseen all organ donations and transplants. However, this centralized control raises ethical concerns about the risks of a single entity overseeing such a critical aspect of health care. UNOS helps to develop, maintain, and re-evaluate allocation scoring systems for various organs which is crucial for determining who is prioritized on the waiting list. There is currently a shortage of organs that only worsens each year; while 90% of adults in the U.S. support organ transplants, only 60% are actually registered donors. The most needed organs in 2024 included kidneys, liver, heart, lungs, and pancreas. With a lack of vital organ donations, it is especially important that UNOS develops policies and rubrics that take into consideration diverse biological factors and eliminate any biases. 

Racial Bias in Kidney Transplant Scoring

There are two scoring metrics that are taken into consideration when matching a donated kidney to a recipient. The Estimated Post-Transplant Survival (EPTS) calculates a percentage that predicts how long a patient is expected to live after the transplant. It calculates this score based on four factors: age, dialysis status, prior organ transplants, and diabetes status. Candidates with an EPTS score in the top 20% are expected to live the longest after post-transplant and are prioritized to receive kidneys. The Kidney Donor Profile Index (KDPI) is a percentage that evaluates the functionality of the kidney from the donor. Lower scores (0-20%) are expected to last the longest and are often first allocated to recipients that have an EPTS score of 20% or lower.

Various research has indicated that white candidates are more likely to have a EPTS score of 20% or lower and have received more kidneys compared to their racial and ethnic minority counterparts. In 2019, both the percentage of white and Black candidates on kidney transplant lists were nearly equal; white patients comprised 38% and Black patients made up 31% of the waitlist. However, white candidates received 65% of pre-emptive transplants while Black patients received only 17%. This biased allocation stems from systemic factors such as longer dialysis duration and higher rates of diabetes among Black patients, which drives their EPTS score to be higher. This is also affected by unequitable socioeconomic factors such as lower education level, decreased insurance, and reducedprovider access. 

To adjust for disparities among the Black community, along with other minority groups, the EPTS score should be adjusted. Instead, the score should place greater emphasis on biological and clinical factors that more accurately reflect a patient’s long-term transplant success. Additionally, socioeconomic disparities (access to health care, insurance coverage, etc.) should be considered to ensure equitable organ allocation. This would not only assist racial minority groups in receiving a kidney more quickly but also lower income groups. In fact, in a recent study evaluating a group of transplant candidates on dialysis, those in the highest income group had a 3-year incidence of waitlist placement of 50% whereas patients in the lowest income group had a 3-year incidence of waitlist placement of 25%. Reforming the EPTS policies to include socioeconomic factors and decreasing emphasis on dialysis duration would more accurately prioritize candidates on the kidney waitlist.

Gender Bias in Liver Allocation Scores

The Model for End-Stage Liver Disease (MELD) is a widely used scoring system in liver transplant prioritization that reflects the severity of a patient's liver disease based on laboratory values such as serum creatinine, bilirubin, and international normalized ratio (INR), which measures blood coagulating ability. It is given by the formula 9.57 × loge (creatinine) + 3.78 × loge (total bilirubin) + 11.2 × loge (INR) + 6.43. The scores range from 6 to 40 with higher scores indicating greater urgency for a liver transplant. Candidates with scores closer to 40 are typically prioritized for transplantation however other factors affect wait time including geographic location and blood type.

Over the past few decades, frequent sex inequities have been identified in liver allocation. One study found that women on the waitlist were 8.6% more likely to die waiting for a liver and 14.4% less likely to receive a liver than men on the list. After decades of research on the issue, both in the United States and in various other countries, many found MELD underestimated the laboratory values in their formula for women. Specifically, women tend to have less creatine and ultimately, less muscle mass than men so on average, they score 2 points lower than men on the MELD score even with the same level of liver function. UNOS finally reformed and implemented the new scoring system (MELD 3.0) in 2023 to account for differences in albumin, bilirubin, sodium, and creatine in women. 

During post-implementation of MELD 3.0, there have been some improvements in equal scoring but many researchers have noted that there are still gender disparities. While MELD 3.0 adjusts for creatinine differences in women by adding 1.3 extra points, this fixed adjustment does not fully account for variability in creatinine-derived MELD scores, which can range from 0.5 to 4.9 points. As a result, the correction may either overcompensate or undercompensate for women's renal function. One study specifically examined the Gender-Equity Model for Allocation incorporating Sodium (GEMA-Na), finding that it better accounts for sex-based physiological differences and reduces waitlist mortality for women. This model has been validated in the United Kingdom and Australia and could serve as a potential alternative to MELD 3.0 in the United States and other countries to improve equity in liver transplant allocation.

Taking Action

UNOS scoring systems have disproportionately disadvantaged racial minorities and women in receiving organ transplants in the United States. EPTS, KDPI, and MELD are just a few examples that do not account for biological and socioeconomic differences that are fundamental for equitable distribution. This has led to higher mortality rates for marginalized and under-resourced populations. UNOS reviews its policies twice a year during the winter (January–March) and summer (July–September) cycles where proposed policy changes are open for public feedback. There are currently various policies and proposals under review, including policies relating to kidney and liver transplants as well as proposals highlighting socioeconomic disparities. Anyone can participate and I encourage taking action to provide feedback and advocate for equitable reforms. Through collective action, we can work toward a system where all patients have a fair chance at receiving life-saving transplants.