Equitable Access to Deceased Donor Livers in the United States: Are We There Yet?

Equity in liver transplantation has and will continue to be a major focus of organ allocation policy. In reality, allocating organs to those patients "most in need" who require a great deal of nuance, particularly in a system like the United States, does not centralize transplant care and instead allows for multiple programs in the same region to compete for the same organ offers. Although the model for end-stage liver disease (MELD) helps to guide decision-making regarding those at greatest risk of succumbing to their liver disease, it is far from all encompassing. To correct for some of these disparities, a system of exception point allocation has been developed to account for scenarios where the laboratory-based MELD score does not capture the true risk of liver-related morbidity and mortality such as in cases of malignancy, pulmonary complications, and metabolic disorders, among others. Previous iterations of MELD exceptions policies, for example, in patients with hepatocellular carcinoma (HCC), have been shown to unfairly advantaged those patients when compared with patients listed without exception points.1,2 Through continued monitoring of nationwide waitlist and transplant outcomes, the transplant community has periodically refined policies to reflect current needs and challenges. In the current iteration, which was implemented in June 2022, MELD exceptions are granted at the median MELD of the donor hospital minus 3 points, which was preceded by median MELD at transplant (MMaT) within 250 nautical miles minus 3 points.3 This change was made to correct early disparities in which a patient had the potential to have disparate MELD scores at different centers in close proximity. Additionally, patients with HCC only qualify for automatic exception points if their tumors is within Milan Criteria (1 tumor <5 cm or 3 tumors all <3 cm) at time of listing or if they are able to be downstaged to Milan Criteria through locoregional therapy. This policy in the United States is based on ongoing organ shortages and that restrictive criteria for transplant with HCC has demonstrated similar outcomes to transplant for patients without HCC.4 Patients with HCC also require a 6-mo waiting period, whereas those without HCC that qualify for exception will receive exception points immediately.3 In parallel to changes in waitlist prioritization, organ allocation policies have evolved in an effort to overcome geographic disparities in access to deceased donor organs. The recent transition from allocation within a donor service area/United Network of Organ Sharing region to the acuity circle model has greatly impacted the practice of liver transplantation in the United States. Acuity circles were implemented to replace previous policies, which enabled broad regional organ sharing but still resulted in geographically variation in MMaT.5 Under this new allocation scheme, rather than organ allocation staying preferentially in the region of the donor, organs are shared within concentric circles (150/250/500 nautical miles) in a tiered system based on their MELD score. Although early perceptions of this new allocation system remain mixed, the most recent OPTN/Scientific Registry of Transplant Recipients Annual Report has demonstrated that liver transplant case volume continues to increase with an overall decrease in waiting time.6,7 These findings signal a positive change in the efforts to enhance equity through a more homogeneous MMaT across the country. In this issue, Ishaque et al,8 examine how these major policy changes have affected those patients that qualify for MELD exception points. Using data from the Scientific Registry of Transplant Recipients, they examine those patients that received an MELD exception for HCC, those with non-HCC–related exception scores, and a reference group of patients that did not qualify for exception. As a consequence of the 6-mo waiting policy, patients in the HCC group may experience drop out before receiving exception points because of disease progression. Thus, the HCC exception group experienced an increase in MELD after 6 mo of waiting time, coinciding with their receipt of exception points. They were also unlikely to undergo transplant in the first 6 mo of waiting time because of a low laboratory-based MELD. Unfortunately for patients with HCC, this trend of lower transplant rates persisted throughout the study period, even after they were awarded exception points. Despite the decrease in transplant rates, there was not a concomitant increase in waitlist deaths or dropout during this study period. Conversely, patients with non-HCC exception points were transplanted at a slightly higher rate than nonexception patients. Interestingly, within the subgroup of patients with non-HCC exception points, patients with cholangiocarcinoma and pulmonary complications such as hepatopulmonary syndrome had higher mortality/waitlist dropout despite higher rates of transplant. This is not particularly surprising given that patients who qualify for MELD exception for pulmonary complications such as hepatopulmonary syndrome are known to experience high waitlist mortality (hence the indication for exception points), whereas cholangiocarcinoma is recognized to have a higher risk of progression than HCC.9,10 Finally, the authors examined center-level variation among patients with HCC exception, non-HCC exception, and no exception status. Within this cohort, they observed significant levels of center-level variation, but some improvement was noted when compared with historical controls. Interestingly for those patients with non-HCC exception, who seemed to have benefited most from the new policies, there was the greatest degree of variation. The authors acknowledge that the study period nearly completely overlaps with the first 2 y of the COVID-19 pandemic. It is possible that admitting patients from home with MELD exceptions, particularly those with pulmonary complications, may have been a logistical and ethical challenge before the introduction of reliable COVID vaccines in early 2021. Thus, ongoing evaluation of waitlist and transplant outcomes in the current waitlist prioritization and organ allocation scheme will be important to understand factors driving the differences observed between regions and centers in this study. Overall, these findings highlight the continued need for data collection and surveillance of subpopulations in clinical liver transplantation, with attention to factors related to national policies that affect patients in that region/country. Although policy is aimed to allow for access to the greatest number of patients, we must continue to move towards equity in organ allocation. It can be difficult to predict unforeseen consequences of policy changes, which may lead to continued inequities for some patients. In this study, patients receiving exception points for cholangiocarcinoma or pulmonary complications do appear to have worse waitlist outcomes, but they are also undergoing transplantation at higher rates than nonexception patients. It will be interesting to see how a more complex algorithm with continuous distribution models impacts liver allocation and waitlist prioritization in the United States once these policies are finalized in the coming year. The concept of continuous distribution aims to develop a patient-centric framework that is centered on a composite allocation score. Continuous allocation aims to move beyond medical urgency and instead factor in posttransplant survival, candidate biology, patient access, and placement efficiency when allocating organs, balanced against those criteria that garner exception points in the current allocation scheme.3 In conclusion, we as a transplant community must continue to collect and analyze high-quality data while also adapting to changes in patient presentation and organ availability to best serve those "most in need."