Modelling the allocation of deceased donor kidneys in Australia

The speaker for the November 2018 meeting of the SA Branch was Dr Phil Clayton. He is a Consultant Nephrologist at the Royal Adelaide Hospital and Deputy Executive Officer of the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry. His talk “Modelling the allocation of deceased donor kidneys in Australia” is part of his current methodological research for the kidney allocation project in Australia.

At the beginning of his talk Phil highlighted the value of transplantation. With respect to increasing survival and improving quality of life, transplantation is a preferred treatment for end-stage kidney disease patients. But only ~8% of patients receive a transplant because of limited resource.

There is a significant gap between dialysis and transplantation in Australia, reflecting the discrepancy between demand and supply of kidneys for transplantation of wait-listed dialysis patients. Around 1000 dialysis patients are wait-listed for a deceased donor kidney transplant in Australia at any given time, and when a kidney becomes available an allocation algorithm is used to determine which patient is offered the kidney. Allocation of deceased donor kidneys involves a complex balance between utility (maximising benefit to society) and equity (ensuring fairness to individuals). The algorithm seeks to achieve the desired trade-off between equity of access to transplantation and the efficient use of a precious resource.

Phil has had a long journey working with the Australian kidney allocation model. He described the current model and its allocation criteria – blood group, waiting time, human leukocyte antigen (HLA) mismatch, ‘highly sensitized’ and childhood – within the setting of the equity versus utility framework. He then described the construction of the allocation model he has developed to simulate the kidney allocation under different algorithms, making use of epidemiological data from the ANZDATA and Organ Donor (ANZOD) Registries, and the National Organ Matching Service. He discussed the metrics for equity and utility and defined the theoretical limits of these metrics under extreme allocation systems.

Phil described alternative allocation systems and explored the potential benefits and trade-offs associated with each. He has used his simulation allocation model to validate outcomes for the current Australian system and to design alternative allocation systems for maximising utility, equity, or to strike a balance between them. Phil finished his talk with a discussion of the projection of survival for waiting list patients, highlighting clear benefits for survival for particular allocation models. A sensitivity analysis of outcomes using his current extended allocation criteria showed the benefits of using his model for a variety of different settings.

The meeting was held at the University of Adelaide in front a healthy-sized audience, many of whom continued discussion with Phil over dinner at a local Thai restaurant.

Shahid Ullah