Organ Allocation: The U.S. Model

Historical Perspective and Legislation

The process of liver allocation in the United States has evolved significantly over the past 4 decades. At the time of the first transplants there was no formal allocation system. There were no established criteria defining brain death, and donor surgery proceeded only after cardiac death. Transplants were limited to a few centers and a few select recipients. Donors were usually identified from within a transplant center, and the organs obtained were transplanted into a patient from that center. Occasionally media sources were used successfully to help obtain an organ for an individual recipient. As a result of rapid growth in kidney transplantation, the Uniform Anatomical Gift Act was passed in 1968. This provided a legal basis for the use of organs and tissue for transplantation and research. At the same time the Ad Hoc Committee of the Harvard Medical School published their criteria for defining brain death. Organs procured after brain death but while cardiac function remained sufficient to maintain organ perfusion were less subject to warm ischemia damage and could be stored for longer times. This opened the way for wider organ sharing. Brain death was legally recognized with the passage of the Uniform Brain Death Act in 1978 and the Uniform Determination of Death Act in 1980.

The rapid growth of transplantation in the 1970s highlighted the need for a more regulated and organized system of organ distribution. The development of organ procurement organizations (OPOs), entities distinct from a specific transplant center, allowed organ retrieval to be conducted in a more systematic manner. OPOs were being established throughout the country and were working within their geographical region with one or more designated transplant centers. There was little in the way of “out-of-region” cooperation or sharing. Organs were offered mainly using recipient waiting time, with little importance given to recipient need or illness.

One of the earliest OPOs, the South East Organ Procurement Foundation (SEOPF), was established in Richmond, Virginia, in 1968. It was instrumental in the development of an early organ allocation system and registry of potential recipients. In 1977 SEOPF formed the first national, computer-based matching system, called the United Network for Organ Sharing (UNOS). In 1984 Congress passed the National Organ Transplant Act (NOTA), which remains the single most important transplant legislation in the United States. Among many things, the act outlawed the exchange of organs for “valuable consideration,” effectively making the sale of organs for transplantation illegal in the United States. It also directed the Secretary of the Department of Health and Human Services to issue a final rule for regulation of organ allocation and transplant policy and led to the establishment of the Organ Procurement and Transplantation Network (OPTN), the agency charged with increasing both the supply of organs for transplantation and the efficiency and equity with which they are distributed.

In 1986 UNOS, now separate from the SEOPF, was awarded the federal contract to administer the OPTN and the national Scientific Registry of Transplant Recipients (SRTR). The mission of the SRTR is to improve transplant patient outcomes by analyzing current results and providing individual centers with risk-adjusted, impartial information that highlights their strengths and indicates specific areas in need of improvement. A NOTA amendment in 1988 required that all OPOs and transplant centers become members of the OPTN and abide by its policies as a condition for receiving Medicare and Medicaid reimbursement. OPOs were also required to designate the geographical areas they would cover; these areas are called donor service areas (DSAs). There are currently 58 DSAs spread over 11 UNOS “regions” ( Figs. 5-1 and 5-2 ). These regions are based on Medicare’s administrative regions for end-stage renal disease (ESRD). In fact, much of the preceding policy was developed in the context of kidney transplantation, with the rules later applied to liver transplantation.

Before 1997, livers were allocated based on a point system composed of waiting time and patient location (intensive care, hospitalized, ambulatory). This system had limitations; candidates could be listed earlier than necessary or simply be hospitalized to obtain more points. In an attempt to more objectively stratify potential liver recipients, UNOS modified listing criteria in 1997. The new criteria were based on the Child-Turcotte-Pugh (CTP) score ( Table 5-1 ), and candidates were grouped as status 1 (fulminant liver failure) or status 2A, 2B, or 3 ( Table 5-2 ) in descending order of priority. Although an improvement, this system too had several shortcomings. The CTP score included parameters that were subjective (ascites and encephalopathy), did not account for renal function, and did not measure severity of liver illness on a linear scale. Within the different status categories, waiting time was still the most important determinant of ranking. There was concern that the system could be “gamed,” and there continued to be a vast regional disparity in waiting times and severity of illness at the time of transplant. Following a report issued by the Institute of Medicine, the Final Rule was amended in 1999 and set forth several performance goals. These included “more accessible, equitable and efficient allocation of organs,” setting “minimal suitability criteria for transplant candidates,” and “distribution of organs over as broad a geographical range as possible.” This ultimately led to the adoption of the Model for End-Stage Liver Disease (MELD) score for liver allocation in February 2002 (described later). Medicare Conditions of Participation for organ transplant programs became effective in 2007. This delineated the specific requirements for personnel and performance standards needed to maintain eligibility for Medicare reimbursement.

Ethical Principles in Liver Allocation

Livers remain a scarce resource, and the growth in the transplant waiting list far exceeds the supply of organs. Available organs must be distributed in a fair and equitable manner. Any allocation scheme must take several ethical principles into careful consideration. First is the principle of justice , which addresses individual need or fairness. For example, directing the next available liver to the sickest candidate is just, as is giving equal access to organs to people of different ages or racial backgrounds, even though outcomes may vary. Second is the principle of utility , which addresses the greater benefit of an intervention or the needs of society as a whole. For example, a utilitarian approach would favor allocating organs to those with the best chance of survival. Third is the principle of autonomy , which respects the individual’s right of self-determination. For example, patients have the right to refuse an organ, and donors have the right to direct an organ to a specific individual. Finally, the principles of benevolence (doing good) and nonmalfeasance (doing no harm) are as applicable to organ allocation as they are to other human endeavors, such as research involving human subjects.

A good allocation system must carefully balance these ethical principles. Using only the principle of justice, one could argue that everyone should be transplanted, regardless of how sick they were or how poor the predicted outcome. A totally utilitarian approach, such as only transplanting candidates with the best outcomes, would also not be considered fair. Should we not offer livers to retransplant candidates because they do worse than primary transplants? Individual autonomy must be respected, but we do not allow people to actively harm themselves, nor would we allow people to choose what race or gender should receive their organs.

These ethical principles are at the core of the current liver allocation system in the United States.