Simulation and analysis of policies for the allocation of liver transplants

Liver transplantation is a vital medical procedure as it helps to prolong the lives and improve the quality of life for a number of people suffering from end stage liver diseases. Unfortunately though, there is a limit to the number of people that may benefit from the operation due to a shortage in the number of livers that are donated. This shortage, conflicting viewpoints, and a changing mix of patients requiring liver transplantation means that it is important to make sure that the livers which are donated are used to their greatest potential (utility) and allocated in a way which is seen as fair (equity). This thesis considers various transplant assessment rule, allocation rule, demand and supply scenarios, to aid in the understanding of the dynamics of the liver transplantation process, and in identifying situations in which equity and utility improve. Survival and Competing Risks Models identify key patient, donor and transplant attributes which influence a patients’ progression through the system. A Discrete Event Simulation model is developed to assess the equity and utility outcomes for how a particular scenario allocates liver transplants to patients. Parametric distributions generated from relevant Survival and Competing Risks models are used to predict the events a patient will experience and to estimate the times at which they will experience the events. Some of the key insights gained into decision making within the UK Liver Transplantation System, are: (1) the need to implement simple rules and rules which change over time, to obtain the best equity and utility output measures as supply, demand and patient mix change; and (2) it is easier to improve the overall utility in the system than the equity, due to the implications of prioritisation