Reducing geographic disparities in kidney and liver allocation

摘要 美国国会在1998年规定，“居住地和列名地都不应成为 但获得肾和肝移植的地域差异是一个主要问题 持续恶化的问题。肾脏是按等待时间分配的，但有8倍的差异 各捐献服务区(DSA)等待时间的中位数。肝脏是用来给候选人的 MELD(终末期肝病模型)得分最高，但中位数MELD相差10分 在DSA中，MELD高的候选人90天内发生LT的可能性从18%到86%不等。 器官采购和移植网络(OPTN)在2012年一致决定 分配…中存在的地理差异高得令人无法接受，“呼吁研究优化的系统。 很少有人提出特别的解决办法，但很少有人探索优化政策，也没有全面的 解决方案从未实施过。就连近期的两大政策变化，股指35和新肾 分配系统(KAS)没有明确解决地域差异问题。喧嚣的科学争论 关于器官可获得性的地理差异是真正的结构性的，还是仅仅反映了 临床实践和器官采购组织的绩效是造成政策僵局的原因。 我们已经开始与OPTN肝脏委员会密切合作，设计优化的共享区 将显著减少获取已故捐赠者肝脏的地理差异。然而，这一初步的 目前的工作受到地理变化的不良衡量标准和未经纠正的供应和 需求。此外，其他有希望的概念，如重新绘制DSA边界，或动态优先排序 没有预先确定的地图的候选人，还没有被探索或评估。最后，没有任何工作 使为肝脏分配而设计的优化模型适应肾分配的不同优先顺序。 我们将开发新的方法，使移植更加公平，考虑到两种临床实践 和分配系统。使用数学最优化和统计推理的创新改编 为了移植政策，我们将隔离地理差异的根本驱动因素，并勾勒出有希望的 使全国各地的候选人都能平等获得已故捐赠器官的政策。我们将解决 以下目标：(1)建立肝肾移植的地理变异指标 对临床实践固有的异质性进行调整；(2)衡量基本的需求和供应 (3)了解近期分配变化对临床决策的影响； 地理差异；以及(4)设计和测试优化的共享系统，以缩小地理差异 同时明确考虑到供应和需求的不确定性。拟议的研究直接解决了一个 并使用OPTN支持的方法。更公平的器官分配将 拯救生命，改善目前在等待名单上面临死亡风险的100,000多名患者的护理。

Summary Congress dictated in 1998 that "neither place of residence nor place of listing should be a major determinant of access to a transplant," but geographic disparities in access to kidney and liver transplantation are a major problem that has persistently worsened. Kidneys are allocated by waiting time, but there are 8-fold differences in median waiting times across donation service areas (DSAs). Livers are intended to go to the candidate with the highest MELD (model of end-stage liver disease) score, but instead median MELD varies by 10 points across DSAs, and 90-day probability of LT for candidates with high MELD varies from 18%-86%. The Organ Procurement and Transplantation Network (OPTN) unanimously resolved in 2012 that "the existing geographic disparity in allocation… is unacceptably high," calling for studies of optimized systems. A few ad hoc fixes have been proposed, but optimizing policy has rarely been explored, and no comprehensive solution has ever been implemented. Even the two recent major policy changes, Share-35 and the new kidney allocation system (KAS), did not explicitly address geographic disparities. Clamorous scientific controversy over whether the geographic disparity in organ availability is truly structural or merely reflects heterogeneity in clinical practice and organ procurement organization performance contributes to the policy stalemate. We have started working closely with the OPTN Liver Committee to design optimized sharing districts that would significantly reduce geographic variation in access to deceased donor livers. However, this preliminary work is currently limited by poor metrics of geographic variation and uncorrected measures of supply and demand. Furthermore, other promising concepts, like redrawing DSA boundaries, or dynamic prioritization of candidates without pre-determined maps, have not yet been explored or evaluated. Finally, no work has been done to adapt optimization models designed for liver allocation to the different priorities of kidney allocation. We will develop new approaches to making transplantation more equitable, considering both clinical practice and allocation systems. Using an innovative adaptation of mathematical optimization and statistical inference to transplant policy, we will isolate the fundamental drivers of geographic disparity and outline promising policies to make deceased donor organs equally available to candidates across the country. We will address the following aims: (1) To construct metrics of geographic variation in access to liver and kidney transplantation that adjust for heterogeneity inherent to clinical practice; (2) To measure fundamental demand for and supply of organs; (3) To understand the impact of recent allocation changes on clinical decision-making and geographic disparities; and (4) To design and test optimized sharing systems that reduce geographic disparity while explicitly accounting for uncertainty in supply and demand. The proposed research directly addresses a Congressional mandate and uses the approach favored by the OPTN. More equitable organ distribution will save lives and improve the care of over 100,000 patients currently at risk of dying on the waiting list.