Evaluation of the Portuguese kidney transplant allocation system: comparative results from a simulation

The distribution of such a scarce resource as deceased donor kidneys should be made by observing a balance between fairness, efficiency and flexibility. Before implementing a new kidney allocation system, these principles should be evaluated and assured objectively. In this article we compare the renal transplant donor-recipient pair selection system implemented in Portugal in 2007 with the Eurotransplant (ET) and United Kingdom (UK) systems. We simulated data for 500 waitlist kidney transplant candidates and 70 deceased donors. Each of the 70 donors was allocated to the best pair of listed candidates, taking into account the criteria of the three allocation systems under analysis. Subsequently, we compare the selected candidate’s groups to kidney transplant. The Portuguese organ allocation model selects candidates with a greater number of incompatibilities with the donor compared to the other two models. Under the Portuguese system’s rules, candidates have a greater age difference with the respective donors (median = 12.5 years) than those selected by the ET system (10 years) or the UK system (8 years). The Portuguese model selected more hypersensitized candidates (15%), but this difference was not statistically significant when compared to the percentage of hypersensitized patients selected by the ET model (10.7%). The Portuguese model has less equity than the other two models under analysis, since the observed disadvantages regarding the number of incompatibilities and age differences with the respective donor are not compensated for by the selection of patients with longer time on dialysis.info:eu-repo/semantics/publishedVersio

Approaches to the Algorithmic Allocation of Public Resources: A Cross-disciplinary Review

Allocation of scarce resources is a recurring challenge for the public sector: something that emerges in areas as diverse as healthcare, disaster recovery, and social welfare. The complexity of these policy domains and the need for meeting multiple and sometimes conflicting criteria has led to increased focus on the use of algorithms in this type of decision. However, little engagement between researchers across these domains has happened, meaning a lack of understanding of common problems and techniques for approaching them. Here, we performed a cross disciplinary literature review to understand approaches taken for different areas of algorithmic allocation including healthcare, organ transplantation, homelessness, disaster relief, and welfare. We initially identified 1070 papers by searching the literature, then six researchers went through them in two phases of screening resulting in 176 and 75 relevant papers respectively. We then analyzed the 75 papers from the lenses of optimization goals, techniques, interpretability, flexibility, bias, ethical considerations, and performance. We categorized approaches into human-oriented versus resource-oriented perspective, and individual versus aggregate and identified that 76% of the papers approached the problem from a human perspective and 60% from an aggregate level using optimization techniques. We found considerable potential for performance gains, with optimization techniques often decreasing waiting times and increasing success rate by as much as 50%. However, there was a lack of attention to responsible innovation: only around one third of the papers considered ethical issues in choosing the optimization goals while just a very few of them paid attention to the bias issues. Our work can serve as a guide for policy makers and researchers wanting to use an algorithm for addressing a resource allocation problem

Contract Development In A Matching Market: The Case of Kidney Exchange

We analyze a new transplant innovation — Advanced Donation, referred to by some as a kidney “gift certificate,” “layaway plan,” or “voucher — as a case study offering insights on both market and contract development. Advanced Donation provides an unusual window into the evolution of the exchange of a single good — a kidney for transplantation — from gift, to simple barter, to exchange with a temporal separation of obligations that relies solely on trust and reputational constraints for enforcement, to a complex matching market in which the parties rely, at least in part, on formal contract to define and clarify their obligations to each other. The transplant community, however, has historically viewed formal contracts in the transplant setting with discomfort, and that traditional discomfort remains evident in current Advanced Donation practice. We conclude that the use of formal contracts in Advanced Donation is likely inadvertent, and the contracts, in a number of ways, are inadequate to tackle the complex, nonsimultaneous exchange of kidneys in which patients donate a kidney before their intended recipients have been matched with a potential donor

Analysis of Allocation Rules for Heart Transplantation

In this dissertation, we utilize several mathematical, optimization, and simulation techniques to improve the outcomes of organ transplantation allocation systems. Specifically, in Chapter 1, we build a Monte Carlo simulation model of the heart transplantation system in the United States that can be used to compare the performance of different allocation policies and predict the future of allocation systems. In Chapter 2, we develop a constrained Markov Decision model of the transplant queuing system and investigate optimal allocation rules for heart transplantation in the presence of certain fairness constraints. In Chapter 3, we introduce a new measure of fairness in the organ transplantation queuing systems. We show that this measure helps improve the performance loss of incorporating fairness considerations in organ transplantation systems, and decrease the price of fairness

Towards fairness in Kidney Exchange Programs

Le traitement médical de choix pour la maladie rénale chronique est la transplantation d'organe. Cependant, plusieurs patients ne sont en mesure que de trouver un donneur direct avec lequel ils ne sont pas compatibles. Les Programmes de Don Croisé de Reins peuvent aider plusieurs paires donneur-patient incompatibles à échanger leur donneur entre elles. Typiquement, l'objectif principal d'un tel programme est de maximiser le nombre total de transplantations qui seront effectuées grâce à un plan d'échange. Plusieurs solutions optimales peuvent co-exister et comme la plupart correspondent à différents ensembles de patients obtenant un donneur compatible, il devient important de considérer quels individus seront sélectionnés. Fréquemment, ce problème n'est pas abordé et la première solution fournie par un solveur est choisie comme plan d'échange. Ceci peut mener à des parti-pris en faveur ou défaveur de certains patients, ce qui n'est pas considéré une approche juste. De plus, il est de la responsabilité des informaticiens de s'assurer du contrôle des résultats fournis par leurs algorithmes. Pour répondre à ce besoin, nous explorons l'emploi de multiples solutions optimales ainsi que la manière dont il est possible de sélectionner un plan d'échange parmi celles-ci. Nous proposons l'emploi de politiques aléatoires pour la sélection de solutions optimales suite à leur enumération. Cette tâche est accomplie grâce à la programmation en nombres entiers et à la programmation par contraintes. Nous introduisons aussi un nouveau concept intitulé équité individuelle. Ceci a pour but de trouver une politique juste pouvant être utilisée en collaboration avec les solutions énumerées. La mise à disposition de plusieurs métriques fait partie intégrante de la méthode. En faisant usage de la génération de colonnes en combinaison au métrique $L_1$, nous parvenons à applique la méthode à de plus larges graphes. Lors de l'évaluation de l'équité individuelle, nous analysons de façon systématique d'autres schémas d'équité tels que le principle d'Aristote, la justice Rawlsienne, le principe d'équité de Nash et les valeurs de Shapley. Nous étudions leur description mathématiques ainsi que leurs avantages et désavantages. Finalement, nous soulignons le besoin de considérer de multiples solutions, incluant des solutions non optimales en ce qui concerne le nombre de transplantations d'un plan d'échange. Pour la sélection d'une politique équitable ayant comme domaine un tel ensemble de solutions, nous notons l'importance de trouver un équilibre entre les mesures d'utilité et d'équité d'une solution. Nous utilisons le Programme de Bien-être Social de Nash afin de satisfaire à un tel objectif. Nous proposons aussi une méthodologie de décomposition qui permet d'étendre le système sous-jacent et de faciliter l'énumeration de solutions.The preferred treatment for chronic kidney disease is transplantation. However, many patients can only find direct donors that are not fully compatible with them. Kidney Exchange Programs (KEPs) can help these patients by swapping the donors of multiple patient-donor pairs in order to accommodate them. Usually, the objective is to maximize the total number of transplants that can be realized as part of an exchange plan. Many optimal solutions can co-exist and since a large part of them features different subsets of patients that obtain a compatible donor, the question of who is selected becomes relevant. Often, this problem is not even addressed and the first solution returned by a solver is chosen as the exchange plan to be performed. This can lead to bias against some patients and thus is not considered a fair approach. Moreover, it is of the responsibility of computer scientists to have control of the output of the algorithms they design. To resolve this issue, we explore the use of multiple optimal solutions and how to pick an exchange plan among them. We propose the use of randomized policies for selecting an optimal solution, first by enumerating them. This task is achieved through both integer programming and constraint programming methods. We also introduce a new concept called individual fairness in a bid to find a fair policy over the enumerated solutions by making use of multiple metrics. We scale the method to larger instances by adding column generation as part of the enumeration with the $L_1$ metric. When evaluating individual fairness, we systematically review other fairness schemes such as Aristotle's principle, Rawlsian justice, Nash's principle of fairness, and Shapley values. We analyze their mathematical descriptions and their pros and cons. Finally, we motivate the need to consider solutions that are not optimal in the number of transplants. For the selection of a good policy over this larger set of solutions, we motivate the need to balance utility and our individual fairness measure. We use the Nash Social Welfare Program in order to achieve this, and we also propose a decomposition methodology to extend the machinery for an efficient enumeration of solutions

Regulation of Organ Transplants: A Comparison Between the Systems in the United States and Singapore

Organ failure is a devastating condition. Transplant offers the hope of “cure” to many patients with end-stage organ failures. The process of organ transplant is highly complicated involving many stakeholders. Important issues, including medical, legal, administrative and ethical, have to be resolved in order to implement a successful organ transplant system and prevent abuses. As such, legislative control of organ transplants is a necessity. Most organ transplant laws cover the donation procedure, types of consent required, establishment of the transplant waiting lists, allocation of organs, certification of brain death, performance of the transplant procedure, and management of post-transplant issues. The regulatory system in the United States builds on the foundation of individual rights and explicit decisions are required for the donation of organs. The operations of the transplant system are largely outsourced to the Organ Procurement and Transplantation Network under a contractual agreement. In contrast, the Singapore system builds on a presumed consent mechanism where residents and citizens are automatically considered as donors upon their death unless they have registered an objection. The operations of the transplant system are centrally managed by the National Organ Transplant Unit within the Ministry of Health. The two systems reflect the unique social and cultural backgrounds of the two countries and they meet the different needs of their people. However, recommendations are made for the United States to strengthen its regulatory system in terms of the need to regulate living donor organ transplants and expand the role of the Food and Drug Administration to ensure the quality and effectiveness of organs and tissues for transplantation

Access to transplantation and transplant outcome measures (ATTOM): Study protocol of a UK wide, in-depth, prospective cohort analysis

INTRODUCTION: There is significant intercentre variability in access to renal transplantation in the UK due to poorly understood factors. The overarching aims of this study are to improve equity of access to kidney and kidney-pancreas transplantation across the UK and to optimise organ allocation to maximise the benefit and cost-effectiveness of transplantation. METHODS AND ANALYSIS: 6844 patients aged 18-75 years starting dialysis and/or receiving a transplant together with matched patients active on the transplant list from all 72 UK renal units were recruited between November 2011 and March 2013 and will be followed for at least 3 years. The outcomes of interest include patient survival, access to the transplant list, receipt of a transplant, patient-reported outcome measures (PROMs) including quality of life, treatment satisfaction, well-being and health status on different forms of renal replacement therapy. Sociodemographic and clinical data were prospectively collected from case notes and from interviews with patients and local clinical teams. Qualitative process exploration with clinical staff will help identify unit-specific factors that influence access to renal transplantation. A health economic analysis will explore costs and outcomes associated with alternative approaches to organ allocation. The study will deliver: (1) an understanding of patient and unit-specific factors influencing access to renal transplantation in the UK, informing potential changes to practices and policies to optimise outcomes and reduce intercentre variability; (2) a patient-survival probability model to standardise access to the renal transplant list and (3) an understanding of PROMs and health economic impact of kidney and kidney-pancreas transplantation to inform the development of a more sophisticated and fairer organ allocation algorithm. ETHICS AND DISSEMINATION: The protocol has been independently peer reviewed by National Institute for Health Research (NIHR) and approved by the East of England Research Ethics Committee. The results will be published in peer-reviewed journals and presented at conferences

Designing a Compensated–Kidney Donation System

Osteochondral lesions of the talus (OLTs) are the third most common type of osteochondral lesion and can cause pain and instability of the ankle joint. Episurf Medical AB is a medical technology company that develops individualized implants for patients who are suffering from focal cartilage lesions. Episurf have recently started a project that aims to implement their implantation technique in the treatment of OLTs. This master thesis was a part of Episurf’s talus project and the main goal of the thesis was to find the optimal implantation angle of the Episurf implant when treating OLTs. The optimal implantation angle was defined as the angle that minimized the maximum equivalent (von Mises) strain acting on the implant shaft during the stance phase of a normal gait cycle. It is desirable to minimize the strain acting on the implant shaft, since a reduction of the strain can improve the longevity of the implant. To find the optimal implantation angle a finite element model of an ankle joint treated with the Episurf implant was developed. In the model an implant with a diameter of 12 millimeters was placed in the middle part of the medial side of the talar dome. An optimization algorithm was designed to find the implantation angle, which minimized the maximum equivalent strain acting on the implant shaft. The optimal implantation angle was found to be a sagittal angle of 12.5 degrees and a coronal angle of 0 degrees. Both the magnitude and the direction of the force applied to the ankle joint in the simulated stance phase seemed to influence the maximum equivalent strain acting on the implant shaft. A number of simplifications have been done in the simulation of this project, which might affect the accuracy of the results. Therefore it is recommended that further, more detailed, simulations based on this project are performed in order to improve the result accuracy.Fokala broskskador på talusbenet är den tredje vanligaste typen av fokala broskskador och kan ge upphov till smärta och instabilitet av fotleden. Episurf Medical AB är ett medicintekniskt företag som utvecklar individanpassade implantat för patienter med fokala broskskador. Episurf har nyligen påbörjat ett projekt där deras teknik ska användas i behandlingen av fokala broskskador på talusbenet. Den här masteruppsatsen var en del i Episurfs talusprojekt och dess huvudmål var att finna den optimala implantationsvinkeln av Episurfs implantat i behandlingen av fokala broskskador på talusbenet. Den optimala implanteringsvinkeln definierades som den vinkel som minimerade den effektiva von Mises-töjningen som verkade på implantatskaftet under stance-fasen i en normal gångcykel. Det är eftersträvansvärt att minimera belastningen på implantatskaftet eftersom en reducering av belastningen kan förbättra implantatets livslängd. En finita element-modell av en fotled behandlad med Episurfs implantat utvecklades för att för att finna den optimala implantationsvinkeln. I modellen placerades ett implantat med en diameter på 12 millimeter på mittendelen av talus mediala sida. En optimeringsalgoritm utformades för att finna implantationsvinkeln som minimerade den effektiva von Mises-töjningen på implantatskaftet. Den funna optimala implantationsvinkeln bestod av en vinkel på 12.5 grader i sagittalplan och en vinkel på 0 grader i koronalplan. Både storleken och riktningen på kraften som applicerats på fotleden under den simulerade stance-fasen av gångcykeln verkade påverka belastningen på implantatskaftet. Ett antal förenklingar har gjorts i projektets simuleringar, vilket kan påverka noggrannheten i resultatet. Därför rekommenderas att ytterligare, mer detaljerade simuleringar baserade på det här projektet görs för att förbättra resultatets noggrannhet

Fairness in operations.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 131-136).This thesis deals with two basic issues in resource allocation problems. The first issue pertains to how one approaches the problem of designing the "right" objective for a given resource allocation problem. The notion of what is "right" can be fairly nebulous; we consider two issues that we see as key: efficiency and fairness. We approach the problem of designing objectives that account for the natural tension between efficiency and fairness in the context of a framework that captures a number of problems of interest to operations managers. We state a precise version of the design problem, provide a quantitative understanding of the tradeoff between efficiency and fairness inherent to this design problem and demonstrate the approach in a case study that considers air traffic management. Secondly, we deal with the issue of designing implementable policies that serve such objectives, balancing efficiency and fairness in practice. We do so specifically in the context of organ allocation for transplantation. In particular, we propose a scalable, data-driven method for designing national policies for the allocation of deceased donor kidneys to patients on a waiting list, in a fair and efficient way. We focus on policies that have the same form as the one currently used in the U.S., that are policies based on a point system, which ranks patients according to some priority criteria, e.g., waiting time, medical urgency, etc., or a combination thereof. Rather than making specific assumptions about fairness principles or priority criteria, our method offers the designer the flexibility to select his desired criteria and fairness constraints from a broad class of allowable constraints. The method then designs a point system that is based on the selected priority criteria, and approximately maximizes medical efficiency, i.e., life year gains from transplant, while simultaneously enforcing selected fairness constraints. Using our method, we design a point system that has the same form, uses the same criteria and satisfies the same fairness constraints as the point system that was recently proposed by U.S. policymakers. In addition, the point system we design delivers an 8% increase in extra life year gains. We evaluate the performance of all policies under consideration using the same statistical and simulation tools and data as the U.S. policymakers use. We perform a sensitivity analysis which demonstrates that the increase in extra life year gains by relaxing certain fairness constraints can be as high as 30%.by Nikolaos K. Trichakis.Ph.D