Designing ABO-Compatible US Kidney Allocation - Resubmission - 1

The 2014 new US Kidney Allocation System heavily prioritized sensitized kidney transplant candidates to provide them with more access to transplantation. However, disparities persist as high-sensitized patients (measured by CPRA level), particularly those with blood type B and O, continue to be underserved. Moreover, about 25% of kidneys recovered for transplant were not utilized in 2023. We propose to evaluate the new kidney allocation policy that extends the eligible candidate pool by allowing ABO-compatible kidney transplants, expanding predominantly ABO-Identical current US kidney allocation. The ABO-compatible kidney allocation can save recovered kidneys at risk of nonuse from waste by serving them to kidney transplant candidates in the greatest need. The policymakers were reluctant to introduce ABO-Compatible, fearing that the problem of lower transplant rates for some blood types would worsen. We propose a novel ABO-adjusted CPRA metric that can prioritize the most disadvantaged candidates to offer them kidneys first. We propose these aims: (I) Estimate the impact: we will use simulated allocation models to evaluate the impact of ABO-Compatible kidney continuous allocation policy, predicting impacts on nonuse rate, and on transplant rates stratified by candidate sex, ethnicity, blood type, and CPRA after a policy change. (II) Identify beneficiaries: we will build models to identify kidneys at high risk of nonuse and candidates requiring increased access or priority that are likely to accept these kidneys. The goal is to build the models and identify the donor and candidate populations who would benefit most from ABO-compatible kidney allocation. (III) Develop optimal ABO-compatible Policy: we will use simulation optimization algorithms to inform the design of an ABO-compatible kidney continuous allocation policy that minimizes organ nonuse and maximizes access. We will estimate the tradeoffs between maximizing transplant rates stratified by sex/ethnicity /blood type/CPRA and increasing the nonuse rate to navigate future allocation policy changes. The introduction of an ABO-adjusted CPRA metric is also proposed to better identify those with the greatest need for a transplant, potentially increasing transplants for highly sensitized candidates. This project aims to directly address the White House Executive Order on Advancing American Kidney Health, by removing overly restrictive policies and providing more opportunities for transplant to highly sensitized candidates of any blood group.