Optimising the management of patients awaiting liver transplantation
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2016
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Melbourne Authors
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Medicine (Austin & Northern Health)
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Doctorate
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Open Access
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© 2016 Dr. Michael Anthony Fink
Abstract
Liver transplantation is a life-saving therapy for selected patients with end-stage liver disease, hepatocellular carcinoma, acute liver failure and metabolic diseases. However, the successful application of liver transplantation is limited by the imbalance between the demand for and the supply of deceased donor organs. Therefore, processes that optimise the prioritisation of and allocation to patients awaiting liver transplantation are essential.
Prediction of the mortality risk of patients waiting for liver transplantation is critical to determine priorities for allocation. A cohort of Australian patients listed for liver transplantation was analysed and medical status, Child-Turcotte-Pugh (CTP) class and model for end-stage liver disease (MELD) were found to be independent predictors of waiting list mortality.
Knowledge of the likely future course of patients at the time of listing for liver transplantation, including the period on the waiting list and after delisting for whatever reason, would inform decisions and discussion with patients regarding the survival benefit of listing for liver transplantation. A scoring system, based on variables that are objective, simple to collect and available at the time of listing, was developed. It had predictive ability superior to CTP and MELD scores.
Prioritisation of patients on liver transplantation waiting lists and allocation of deceased donor livers has been based on clinical judgement in Australia and New Zealand. MELD score, an objective measure of the degree of liver failure and mortality risk, is a common allocation tool. These methods of prediction of waiting list mortality were examined in a cohort of patients waiting for liver transplantation. MELD score was more likely than clinical judgement to prioritise for allocation patients who subsequently died waiting for a donor liver. An allocation system based on MELD rather than clinical judgement would significantly alter organ allocation in Australia and may reduce waiting list mortality.
Most systems of organ allocation for liver transplantation focus on the risk of dying on the waiting list. However, post-transplantation outcomes, which reflect the utility of transplantation, are also important. Allocation by survival benefit aims to allocate to the patient who, with a given organ donor, has the greatest increase in life-years gained by transplantation over remaining on the waiting list. Validation of models of waiting list, donor and recipient risk, that are used to calculate survival benefit, was performed and demonstrated that these generally performed well in a patient population independent of that in which the models were derived.
A detailed analysis of allocation in Australia and New Zealand has not been performed previously. Prioritisation is undertaken using clinical judgement informed by MELD score. Allocation decisions take into account acuity and donor quality. Transplant patients overall, recipients of standard criteria and extended criteria grafts and of split or reduced left lobes had a higher acuity than those who remained on the waiting list, but patients selected to receive split right lobes had similar acuity to those who remained on the waiting list.
Patients with high MELD scores have a high risk of dying on the waiting list and only have a short window of opportunity for liver transplantation. Inter-regional sharing of livers across Australia and New Zealand for high MELD patients might increase the opportunity to rescue them. A simulation of several models of inter-regional sharing demonstrated that the rules of allocation, such as the MELD threshold above which inter-regional allocation would occur, had important effects on the number of patients potentially rescued and the cost in terms of the number of livers that would be shipped and the increase in shipping distance and cold ischaemia time. This information will inform decision making regarding the implementation of inter-regional sharing for high MELD patients.
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Keywords
liver transplantation, waiting list, mortality, allocation, model for end-stage liver disease, MELD, organ sharing