Monday, December 6, 2021

Deceased organ allocation in the U.S., moving towards a more continuous system--Martha Pavlakis in Transplantation

 In the latest issue of Transplantation a clear description of how the transplant community is planning to move towards a more continuous way of allocating organs, in ways that have already begun (so that e.g. a lung transplant candidate in Manhattan won't be ineligible for a kidney from a deceased donor across the river in New Jersey).  One element of this that worries me is that a weighting system for priorities will be derived from focus groups of interested parties, using the Analytic Hierarchy Process, which is an orderly, matrix based process for aggregating opinions that doesn't have any ability to integrate different aspects being evaluated from the point of view of how they might effect relevant transplant outcomes, or consider how they might influence incentives for diagnosis and treatment. So I anticipate that organ allocation will continue to be in motion for the foreseeable future.

Continuous Distribution in Organ Allocation: Stepping Back From the Edge  by  Martha Pavlakis,  Transplantation: December 2021 - Volume 105 - Issue 12 - p 2517-2519, doi: 10.1097/TP.0000000000003886

"Organ allocation priorities are determined according to policies developed by the Organ Procurement and Transplantation Network (OPTN), which is operated by United Network for Organ Sharing (UNOS). In 2016, a significant shift began which will culminate in a transition of all organ allocation to be determined in the framework of an approach known as continuous distribution. The most reductive description of the change from current allocation to continuous distribution is that it will change from a classification-based (or bucket-based) system to a points-based system without hard borders. 


"The removal of hard boundaries in the continuous distribution system of allocation has been reviewed elsewhere6,7 and is best described by outlining the steps in its development. The steps include (1) identifying and categorizing candidate attributes; (2) building of a rating scale that assigns values for each attribute, such as candidate blood type, using UNOS and SRTR data; and (3) assigning weights to each attribute to determine how much that attribute will contribute to the candidate’s final score. This process has several parts: first, there needs to be a specific weight assigned to each attribute such that it can be prioritized against each of the other attributes. As a next step, the attributes need to be converted into points. (4) A framework will be built where a composite score is determined by combining weights and rating scales. To do this, a sensitivity tool called the analytic hierarchy process (AHP) will inform the development of the framework through a prioritization exercise.8 In these exercises, participants compare 2 attributes against each other and select their level of importance when considering a candidate for organ transplant. The information from multiple rounds of these exercises will be used to inform the weight of each attribute to the overall score. The AHP method was chosen because it has been used effectively by other healthcare groups to involve patients in making clinical decisions.9 The “participants” in this AHP method are the same participants that engage in public comment for policy change—member centers, individuals, OPOs, organizations with a vested interest in transplant such as the American Society of Transplantation, and the general public. Participants will weigh the trade-offs between effectiveness/benefit and medical urgency. Using focus groups, Oedingen et al convincingly highlighted the importance of preference studies to elucidate public preferences in organ allocation, which has multiple and sometimes competing goals.10

"Once the community has agreed on a proposed continuous distribution system, the SRTR will perform modeling to identify any potential unintended consequences of the proposal. The modeling will estimate the benefits of the new proposal and inform any needed improvements. (5) After considering community input through public comment, modeling and analysis, and committee project work, the kidney committee will then propose a composite score as a policy proposal. (6) Finally, a policy proposal will be presented to the OPTN Board of Directors for approval. Once approved, implementation of the policy is projected to take approximately 12 mo due to programming changes and education for the transplant community."

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