Optimal Policies for the Acceptance of Living- and Cadaveric-Donor Livers

Transplantation is the only viable therapy for end-stage liverdiseases (ESLD) such as hepatitis B. In the United States,patients with ESLD are placed on a waiting list. When organsbecome available, they are offered to the patients on this waitinglist. This dissertation focuses on the decision problem faced bythese patients: which offer to accept and which to refuse? Thisdecision depends on two major components: the patient's currentand future health, as well as the current and future prospect fororgan offers. A recent analysis of liver transplant data indicatesthat 60\% of all livers offered to patients for transplantationare refused.This problem is formulated as a discrete-time Markov decisionprocess (MDP). This dissertation analyzes three MDP models, eachrepresenting a different situation. The Living-Donor-Only Modelconsiders the problem of optimal timing of living-donor livertransplantation, which is accomplished by removing an entire lobeof a living donor's liver and implanting it into the recipient.The Cadaveric-Donor-Only Model considers the problem ofaccepting/refusing a cadaveric liver offer when the patient is onthe waiting list but has no available living donor. In this model,the effect of the waiting list is incorporated into the decisionmodel implicitly through the probability of being offered a liver.The Living-and-Cadaveric-Donor Model is the most general model.This model combines the first two models, in that the patient isboth listed on the waiting list and also has an available livingdonor. The patient can accept the cadaveric liver offer, declinethe cadaveric liver offer and use the living-donor liver, ordecline both and continue to wait.This dissertation derives structural properties of all threemodels, including several sets of conditions that ensure theexistence of intuitively structured policies such as control-limitpolicies. The computational experiments use clinical data, andshow that the optimal policy is typically of control-limit type

Estimating the price of privacy in liver transplantation

In the United States, patients with end-stage liver disease must join a waiting list to be eligible for cadaveric liver transplantation. However, the details of the composition of this waiting list are only partially available to the patients. Patients currently have the prerogative to reject any offered livers without any penalty. We study the problem of optimally deciding which offers to accept and which to reject. This decision is significantly affected by the patient's health status and progression as well as the composition of the waiting list, as it determines the chances a patient receives offers. We evaluate the value of obtaining the waiting list information through explicitly incorporating this information into the decision making process faced by these patients. We define the concept of the patient's price of privacy, namely the number of expected life days lost due to a lack of perfect waiting list information.We develop Markov decision process models that examine this question. Our first model assumes perfect waiting list information and, when compared to an existing model from the literature, yields upper bounds on the true price of privacy. Our second model relaxes the perfect information assumption and, hence, provides an accurate representation of the partially observable waiting list as in current practice. Comparing the optimal policies associated with these two models provides more accurate estimates for the price of privacy. We derive structural properties of both models, including conditions that guarantee monotone value functions and control-limit policies, and solve both models using clinical data.We also provide an extensive empirical study to test whether patients are actually making their accept/reject decisions so as to maximize their life expectancy, as this is assumed in our previous models. For this purpose, we consider patients transplanted with living-donor livers only, as considering other patients implies a model with enormous data requirements, and compare their actual decisions to the decisions suggested by a nonstationary MDP model that extends an existing model from the literature

Split Liver Transplantation

Liver transplantation is the most effective treatment for the patients with acute liver failure or end-stage liver diseases. Liver transplantation is also indicated for patients with hepatocellular carcinoma to yield a best result if the tumor/tumors meet Milan criteria, University of California San Francisco(UCSF) criteria, or up-to-seven criteria. It is no doubt that more and more people need liver transplantation to save their lives. However, liver donation is always short to match the demand of liver transplantation. Therefore, how to expand the donor pool to increase the opportunities of liver transplantation is paramount. Splitting liver is one of the ways to expand the donor pool and offers an additional chance of liver transplantation. At the beginning of split liver transplantation (SLT), the liver was split and transplanted to an adult and a child. Now, the liver can be split into full right and left lobes and transplanted to two adults. When split liver transplantation is to be performed, there are many considerations that should be clarified. With the improvement of surgical skill, the outcomes of split liver transplantation are similar to that of deceased whole liver transplantation. It is worth to promote the policy of split liver transplantation

CADAVERIC VS. LIVE-DONOR KIDNEY TRANSPLANTS: THE INTERACTION OF INSTITUTIONS AND INEQUALITY

“In 1991, the World Health Assembly approved a set of Guiding Principles which emphasize voluntary donation, non-commercialization and a preference for cadavers over living donors” (World Health Organization). We investigate whether factors such as inequality, rule of law and religion have any effect on the ratio of cadaveric transplants to all transplants. Using an unbalanced annual dataset from 64 countries over 1993-2004, we show particularly for developing countries that an improvement in equality and rule of law encourage cadaveric kidney transplants. Religion also plays an important role in that relationship.

The Gift of Life:Ethical and Social Consequences of Organ Donation

Organ transplantation is a comprehensive subject covering many different issues: medical, social, political and economic. This paper focuses on the ethical and social implications of organ donation. Also presented are the different policy and program options attempting to meet the immense demand for donors. Part I addresses an initial obstacle to organ transplantation-- consent. Part II describes the ethical conflicts related to donor sources. Part III examines possible transplant policy solutions and the potential ramifications of their implementation. Part IV concludes with suggestions for future solutions and a recommendation for an effective policy which can increase the organ donor supply, while accounting for consent and respecting individual personal beliefs and wishes