Project Summary/Abstract The liver transplant waitlist in the United States exceeds the number of transplants performed by over 3,000 people annually. Despite this shortage, 10% of donor livers are considered “marginal” in quality and discarded annually. Marginal donor livers (MDLs) have higher risk characteristics such as donation after cardiac death (DCD), older age, steatosis, and national sharing. With careful donor-recipient matching, MDLs can be used without compromising patient survival, weighing organ quality risks against the risk of waiting for a “better” organ. MDLs therefore represent an underutilized but valuable source of transplantable livers. Despite a growing amount of evidence showing good outcomes for MDLs, adoption of this practice remains variable across centers. In attempt to explain this, our objective with this project is to examine the process of decision-making for MDL transplantation and to identify areas for process improvement. Our central hypothesis is that use of MDLs varies across transplant centers, even within the same region, and is influenced by donor, recipient, and institutional factors. We propose a mixed-methods approach to identify factors associated with MDL utilization using national transplant registry data and qualitative interviews with New England transplant centers. We will perform a quantitative study of donor-recipient organ offers using a novel database of allocation match run results to identify donor and recipient factors influencing a surgeon or center’s decision to accept an MDL for transplant. Next, to elucidate key steps in the decision to transplant an MDL, we will conduct semi-structured interviews with transplant surgeons from New England’s liver transplant centers to identify barriers and facilitators to transplanting MDLs, with a focus on surgeon decision-making and structural or systemic influences at the center level. Our proposed research will deconstruct the complex decision-making underlying the decision to transplant an MDL. We expect the results of this study will identify actionable targets for process improvement and policy development. This work will provide a framework for studying transplant center practices and surgeon decision-making. By focusing on New England for the qualitative portion of this proposal, we will show feasibility on a smaller regional level with the intention to later scale our methods and results across other regions, ultimately inciting regionally driven efforts of collaborative process improvement. The knowledge acquired from this work has the potential to increase access to liver transplantation by optimizing use of available organs. By performing this work, Dr. Cron will receive mentored training in qualitative methodology and clinical transplantation science, facilitating his development into an independent surgeon-scientist and a leader in transplant surgery.