Waitlist Eligibility and Disparities in Transplant Access

Posted on September 21, 2022 by AJKDblog in Commentary // 0 Comments

Adrian Whelan @AdrianWhelan6

Dr. Adrian Whelan is a Transplant Nephrologist at University of California, San Francisco. He completed the AJKD Editorial Internship during its inaugural year in 2018 and is a former NephMadness region writer. He is interested in practice patterns of transplant centers and reducing disparities in transplant care.

There are over 138,000 patients on the waiting list for a kidney transplant in the United States, as the demand for kidney transplants continues to greatly exceed the number of organs available for transplantation. This limits the number of patients who can benefit from the improvements in quality of life and survival offered by kidney transplantation. Ensuring equitable access to such a limited supply of organs is a major priority of the transplant community, including the Organ Procurement and Transplantation Network (OPTN) which oversees policy development for organ allocation in the United States. Indeed, the OPTN includes providing equity in access to transplants as one of its four key goals in its strategic plan.

Waiting time is one of the main drivers of organ allocation under the current OPTN policy, which allows waiting time accrual to begin once glomerular filtration rate (GFR) is ≤20ml/minute for patients not receiving dialysis therapy, or from the date of regularly administered dialysis for patients receiving dialysis therapy. A study recently published in AJKD by Chu et al. examined whether reaching the allocation policy GFR of ≤20ml/min was associated with a difference in time to needing kidney failure replacement therapy (KFRT) across racial/ethnic groups. The authors also evaluated the impact on their findings of removing the race variable when estimating GFR.

This was a retrospective cohort study that used electronic health record data from the OptumLabs. The cohort included adults having an eGFR value ≤20ml/min/1.73m² on out-patient lab testing and who had not previously received dialysis therapy. The authors main findings were that non-Hispanic Black and Hispanic patients were more likely to progress to KFRT than non-Hispanic White patients, from the time of first eGFR ≤20ml/min/1.73m². These findings were partially attenuated when non-Hispanic Black patients were assigned the non-Black value when estimating GFR. In adjusted analysis, there was an increased risk of KFRT among non-Hispanic Black (hazard ratio 1.28 [95% CI 1.15-1.43]) and Hispanic patients (hazard ratio 1.66 [95% CI 1.18-2.31]) compared to non-Hispanic White patients.

Fig 2 from Chu et al, AJKD © National Kidney Foundation, showing cumulative incidence of kidney failure with replacement therapy (dialysis or transplant) by race/ethnicity starting from first outpatient eGFR ≤20ml/min/1.73m²

Relevant to this study is the movement of health systems and other stakeholders away from the use of race in the estimation of GFR, contributed to by the work of the NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease. The current study reports that removing race from the eGFR calculation could result in earlier waitlisting of Black patients by about 6 months. However, even when Black patients were assigned the non-Black GFR estimate they progressed to KFRT more quickly than non-Hispanic White patients. Similarly, Hispanic patients progressed to KFRT more quickly than non-Hispanic White patients even though there is no race adjustment applied to Hispanic patients when estimating GFR. This importantly highlights that removal of race from GFR estimation will not fully resolve disparities in access to transplantation and that Black and Hispanic patients will continue to have reduced opportunities for pre-emptive transplantation and pre-dialysis waiting time accrual if this is the only step taken.

While noting that any single change will not solve the complex and multifactorial disparities in access to kidney transplantation, the authors allude to a potential solution of using risk models, such as the Kidney Failure Risk Equation, to predict time to KFRT rather than reliance on eGFR alone to evaluate risk of future KFRT, as in the current organ allocation policy. However, they also note that capturing the observed racial/ethnic differences in CKD progression in prediction models is problematic, as race/ethnicity is a social rather than biological construct with issues surrounding individual interpretation of race and uncertainties of how to categorize patients with mixed race, for example. This is compounded by movement away from race-based medicine.

More recently, the National Academies of Sciences, Engineering, and Medicine (NASEM) released a report on Realizing the Promise of Equity in the Organ Transplantation System offering another potential solution. The report recommended eliminating pre-dialysis waiting time points from the kidney allocation system to reduce racial and ethnic disparities in the kidney allocation system. This has the potential to remove the disparities observed by Chu et al. and bypass issues surrounding categorization of patients based on the social construct of race. However, this change would be likely to reduce pre-emptive transplantation from deceased donors substantially. Pre-emptive transplantation has been associated with better graft and patient survival outcomes compared to transplantation following initiation of dialysis, even if treated with dialysis for a relatively short period of time. The NASEM recommendation could therefore lead to an unintended consequence of reducing the overall benefit provided by the limited supply of kidney organs available for transplantation. With this in mind, the NASEM recommendation needs to be considered carefully as it may contradict one of the other key goals of the OPTN—to improve transplant recipient outcomes.

It’s important to regularly evaluate and update the organ allocation system policy to meet the goals of the OPTN and the transplant community. Continued work is needed to ensure removal of inequities and to best serve patients with kidney disease.