Inequity in access to liver transplant care: Time to make the invisible visible

In this issue of Liver Transplantation, Jackson and colleagues present a well-executed and well-written evaluation of the association between sociodemographic factors and waitlist-related outcomes in liver transplantation in the United States. While residence in a zip code with unfavorable social determinants of health (SDOH) was associated with a greater likelihood of listing with a MELD score over 30, this association was no longer significant when adjusted for race/ethnicity in addition to age, sex, BMI, insurance, disease etiology, and center volume. The authors took the further step of stratifying by age and race, finding that area-level SDOH remained an important factor in listing at high MELD for Hispanic-White candidates and those over age 60.^[1] Overall, these results suggest the presence of either referral or evaluation barriers for more socially vulnerable patients, which is a critical reminder of ongoing systemic inequities in access to liver transplantation.

Like many good studies, this manuscript raises more questions than it provides answers. A notable feature of the most disadvantaged areas was that they were more frequently located in major population centers and closer to liver transplant centers. This closer proximity to specialized care likely mitigates the harmful impact of unfavorable SDOH. For example, Cicalese et al demonstrated that proximity to a liver transplant center was associated with the risk of waitlist mortality, while Barritt et al showed that the number of gastroenterologists in a community influenced the likelihood of receiving a transplant.^[2,3] Moving forward, it would be of interest to investigate differences in the listing acuity of patients from disadvantaged zip codes, stratified by distance to a transplant center, as this investigation suggests an interplay between SDOH and proximity to specialized transplant care. Another natural application of spatial epidemiology informed by this study would be to examine the topography of unfavorable SODH as it relates to liver transplant access. Mohan et al found that impoverished counties surrounded by other impoverished counties (termed “concentrated poverty”) had lower rates of kidney transplantation than impoverished counties surrounded by wealthier neighbors.^[4] It would be worthwhile to study whether similarly poor liver transplant–related outcomes are present in geographic clusters of unfavorable SODH.

If we assume that systematic listing at a high MELD score, as found by the authors, is a symptom of late referral and poor access to care, then this study adds to the steadily growing body of literature demonstrating that our transplant system is not serving the broader end-stage organ failure population as well as it should.^[5,6] The Institute of Medicine (IOM) identified the pre-waitlist phase as the location of the majority of barriers to transplantation over 20 years ago,^[7] a finding later verified by Bryce et al, ^[8] among others. How, then, are we to go about starting to address this well-recognized problem?

The first step in addressing disparities in referral for transplant is actually defining the issue through systematic, comprehensive data collection. Without a national data source of end-stage liver disease (ESLD) burden, this vulnerable population is effectively invisible to transplant centers, researchers, and policymakers. In contrast to the lack of data on ESLD, estimates of end-stage kidney disease are captured in the United States Renal Data System, a federally mandated database inclusive of every patient who begins hemodialysis in the United States. This database enables research focused on the path from end-organ disease to transplantation, facilitating targeted, stepwise interventions. It should be our goal to develop a similar data system for ESLD. To be fair, the institution of dialysis is a fixed endpoint that is easy to define, and there is no clear corollary in ESLD. In addition, we only have data on end-stage renal disease once patients are on dialysis; it would be useful to capture data on advanced kidney and liver disease at an earlier stage to assess strategies that might prevent the need for transplantation.

Second, we in the transplant community need to recognize our responsibility to patients before their addition to the waitlist. Traditionally, the OPTN has interpreted the Final Rule as limiting its purview to transplant candidates (ie, those on the waitlist) and recipients, which the IOM recognized as a “gap in oversight” that “presents a significant challenge to ensuring fairness and equity in the organ transplantation system.”^[9] To remedy this gap, we agree with the IOM’s recommendation that the Department of Health and Human Services “extend its regulatory oversight of the organ transplantation system beginning, at least, at the time a patient reaches end-stage organ failure.”^[9] Our responsibility is not to the metrics by which we are judged, but to the individuals we have the power to help.

Finally, we must deploy interventions targeting vulnerable populations and regions, namely by increasing access to subspecialty care, encouraging prompt transplant referral, and ensuring equity in evaluation. “Risks” associated with transplanting more vulnerable populations should be carefully considered for forms of bias, such that individuals are not unduly denied lifesaving care.

With momentum surrounding the OPTN Modernization Act, now is the time to take action to overhaul our transplant system to ensure that all patients suffering from ESLD finally get the attention they deserve.

Abbreviations:

ESLD

end-stage liver disease

IOM

Institute of Medicine

SDOH

social determinants of health