Diagnosing disparities in existing and proposed allocation systems for kidney transplantation - PROJECT SUMMARY/ABSTRACT
All patients in the US with kidney failure should have fair and timely access to the benefits of kidney
transplantation, but long-standing disparities and ineffective organ allocation policy have frustrated that
promise. There have been multiple changes to the kidney allocation system to address transplant disparities,
most recently in March 2021 when kidneys were prioritized to candidates listed within a 250 nautical mile
radius of the hospital of the deceased donor (KAS250), rather than within fixed donor service areas.
Because kidney organ allocation uses complex rules that incorporate several patient characteristics to
determine which candidates receive deceased donor organs, changes aimed at mitigating one problem often
have unintended consequences. For instance, a 2014 change to the allocation system increased kidney
transplants for sensitized candidates but unintentionally reduced transplants for pediatric candidates 0-6 years
of age. We therefore propose to comprehensively study the impact of the new allocation system, both in
ensuring equitable distribution of organs to transplant centers across the US based on patient priority on the
waitlist, which was the aim of the policy change, and the new policy’s impact on kidney transplant rate
disparities for vulnerable populations who have historically been disenfranchised by allocation policy.
The new KAS250 system will ultimately evolve to continuous allocation where transplant candidate distance
from donor hospital will be one weighted component among other patient factors. Our group has an ongoing
R01-funded study (R01DK132395) to design a continuous allocation system for kidneys using a
computationally intensive simulation and optimization algorithm that simulates thousands of possible
continuous allocation systems. We will apply our equity metrics to simulation outputs to determine the impacts
of any proposed allocation system on vulnerable populations. We will also incorporate our metrics into the R01
algorithm to design a continuous allocation system that prevents inequity by design.
In this project, we will accomplish the following aims: (1) To evaluate whether the supply of organs is equitably
distributed among US transplant centers in the new KAS250 system (2) To develop novel metrics that describe
the landscape of disparities for vulnerable populations in the new allocation system and (3) To evaluate
projected disparities from simulations of proposed continuous allocation systems. The equity metrics of Aims 1
and 2 will be calculated from adjusted regression models using national databases. By performing this
research while pursuing a PhD in Epidemiology at the richly resourced NYU Langone Vilcek Institute, Dr.
Liyanage will receive rigorous training in epidemiology, research methodology, conceptual frameworks of
social determinants of health, and simulations and machine learning as it applies to health policy, furthering her
goal of becoming an independent surgeon-scientist by following the example of her mentor, Dr. Dorry Segev.
