Systems of organ allocation

 

One of the key features of voluntary transplant systems worldwide is that they employ various non-price mechanisms to ration the allocation of organs to patients, which indicates quite clearly that a shortage as the demand expressed for organs vastly exceeds the available supply. Organ rationing is unique though, for while the rationing of other goods may prove to be an inconvenience to those who desire them but who can survive if they go without, when it comes to organs, we confront a matter of life and death, as those who are unfortunate enough not to receive an organ face, in a figurative sense, a death sentence. With respect to the matter of rationing, the public have generally accepted, without dissent, the assurances provided by clinicians that organs would be equitably allocated to patients. However, in recent years, questions have been aired concerning “the fairness of the procedures and criteria used by surgeons, hospitals and medical centers to select transplant recipients” [1]. Here, the debate has arisen since it has become increasingly clear that while those in the medical domain have taken a prominent stand against using some economic tools, such as rationing, in the transplant sector as being inappropriate to the general medical environment, they have themselves used different non-medical rationing criteria to allocate organs.

 

When looking at the allocation of organs, we must first consider how rationing is used to whittle demand down from an absolute number of potential recipients to the much smaller number of patients that are officially depicted as requiring organs. Ideally, the number of people who are eligible for a transplant is made up of all those individuals who are suffering from end-stage organ failure of a related tissue problem. With these patients, a medical diagnosis of their condition is required as the precursor to entry on a transplant waiting list, as “referrals play a critical role in determining who does and who does not get a chance at a transplant” [2]. Referrals for transplants are not always made though, in which case the number of potential organ recipients is slowly reduced by either intentional or inadvertent medical omission. For example, some doctors may not refer patients if they are not aware of the latest advances in transplantation, might feel that the relevant cost-benefit value of a transplant is not good enough, or could have a vested interest in keeping patients on alternate forms of therapy. In addition, economic factors play a role in the probability of obtaining a referral, for while “an individual with good primary care has a better chance of being identified as someone in need of a transplant” [3],  if a person cannot afford the services of a doctor in the first place, then he or she has no chance of finding out that there is an end-stage organ problem, never mind obtaining a referral.

 

However, should patients indeed manage to be referred to a transplant centre, they must then go through a second filtering stage, where a variety of factors need to be considered by those who administer the transplant waiting list before admission is granted. Obviously, medical criteria are critically examined, with “candidates for heart, liver and lung transplants expected to die within one year in the absence of transplantation” [4]. Applicants must also demonstrate that they have no medical contra-indications and are able to endure the physical rigours of the procedures involved, with high surgical risk candidates, for example, rarely being accepted on to the waiting list except by the most experienced (or ambitious) transplant surgeons [5]. Special consideration is also placed on determining whether the age of recipients is likely to affect their survival prospects. While older patients were excluded from receiving organs in the past due to poor survival prospects, with the arrival of drugs such as cyclosporine, their ability to receive a new organ has increased substantially in recent years, with observers noting that physiological age is more important to patient survival than chronological age [6].

 

In addition to these medical considerations, other, more questionable, variables are considered in deciding on who should enter a transplant waiting list. For example, psychological issues are examined where a patient must express a clear commitment to receiving the transplant and to meeting the requirements of the post-operative treatments that they may have to take for the rest of their lives. The ability of patients to overcome the emotional stresses that will be placed on them and the strength of their support network are also considered, as these are believed to impact greatly on their expected quality of life [7]. Objections have been raised over such assessments, since it is felt that family circumstances and personal traits may be beyond the control of the applicant, in which case any exclusion on such a basis may not only be unethical, but also illegal if it intervenes with a patient’s basic rights.

 

More general social criteria are also considered where, although organs are no longer allocated on the basis of obvious social worth, less direct ways of assessing an individual’s value to society are considered. This can clearly be seen by the debate that has developed in the USA over the manner in which priority access to transplantable livers has changed, where people suffering from acute liver failure have been favoured over those with chronic infections such as hepatitis and alcoholic liver disease [8]. Here, it has been argued that alcoholic patients should be disqualified from receiving liver transplants as their conditions are solely due to their personal conduct, and so they are morally blameworthy for being infected. The most obvious flaw with this argument is that heart transplant candidates with coronary disease are not turned away even if they ignored medical advice that could have helped them beforehand, nor are patients exposed to other judgements concerning social worth (e.g. whether they cheat, are violent, adulterers, etc), so it seems incongruous that such a dubious moral double-standard is applied to only certain patients [9]. In addition, it is felt that alcoholics display poor stewardship of their bodies and are likely to fare worse than other people with a new organ due to their poor habits. The problem here lies in the fact that any restriction may be immoral, as past behaviour is no guide to future performance, with alcoholic patients not only having an incentive to sober up when given the responsibility of caring for a new organ, but also demonstrating in medical studies that they can have better survival prospects than certain other categories of patient [10].

 

In addition to alcoholics, moral judgments have also been applied to other patients as well, as happened when British doctors were accused of making a moral rather than medical decision when refusing a young girl a transplant. In this case, the girl was to die because she took half an ecstasy tablet and was, according to the doctors, guilty of displaying troublesome behaviour [11]. Other examples of social worth being used as a criterion of allocating organs include the granting of special status to children or, possibly more acceptable from a political (but not medical) perspective, barring foreign nationals from receiving a locally donated organ.

 

Finally, economic considerations play a major role in determining who will receive an organ and how well a patient is likely to fare in the long run, even if this is seen as undesirable by members of society. Transplantation is an extremely costly form of surgical intervention, with estimates from the USA (where costs are admittedly greater than elsewhere) stating that in the first year of surgery, kidney grafting costs about $35,000; heart operations $60-100,000; and liver transplants $150-200,000 per patient [12]. Now, while state funding and subsidised treatment may be provided to help recipients, a clear ability in a private capacity to cover part of these costs may also need to be demonstrated. For many people, this is not always possible, so they may either have to give up any hope of receiving a transplant or they may be forced into a life and death struggle of raising funds to cover their costs.

 

Once a person has entered a waiting list, he or she is then forced to wait before an organ can be received, with the duration of the delay depending to a large degree on the type of allocation system in use. Listed below are the main rationing systems that exist, along with their merits and flaws.

 

i) Best biological match

With this system, organs (in particular kidneys) are allocated to recipients based on the quality of their antigen match, with the probability of receiving an available organ rising as the number of identical antigens between donor and recipient increases. The rationale behind this system rests on the fact that the higher the overall antigen match, the higher is the expectation of graft survival for the recipient. From this, the lower will be the need for retransplantation, where the recipient may require an additional organ transplant due to the failure of a prior graft. Maximum use is thus made of all available organs, for the lower the number of retransplants, the greater is the number of people who are offered the chance of receiving an organ.

 

While allocating organs on this basis is efficient, as organs go to those people to whom they are most genetically suited, questions have been raised about how equitable this approach is. This is primarily because this system does not consider factors such as physical need or the time already spent waiting for an organ as allocation criteria, which may discriminate against patients whose general prospects of receiving an organ are low. For example, patients with rare antigens may be forced to remain on a waiting list for many years, as they will always be passed over in favour of others who have waited for considerably less time for an organ, simply since they have a better antigen match than them. Similarly, highly sensitised patients may also be less likely to receive an organ, with patients having type-O blood being particularly affected and having to wait, on average, a longer period of time to receive an organ than people from other blood groups. This is because although these patients can serve as universal blood donors, they can only receive type-O blood, which means that they have to also rely solely on organs provided by donors of their own blood group.

 

Now, while these general fears concerning equity are valid, there is a counter response that this approach is, in its own manner, highly equitable too. If patients successfully receive organs without rejection, the size of the waitlist can decrease dramatically – as this happens, the probability of receiving an organ for those who remain can increase significantly as they no longer need to compete with earlier recipients for organs that subsequently become available[13].

 

ii) Waiting time

The most egalitarian way of distributing organs is to operate a “first come, first served” system, where organs are strictly allocated to potential recipients in the order in which they entered the waiting list. This method is equitable for, if we assume that people were operating under a “veil of ignorance” concerning future events, then most respondents would be likely to agree that those who make the first claim to receiving an organ by joining a waiting list should also be the first to receive a transplant. The advantage to medical professionals of this system is that it is familiar, with queuing already being used to allocate scarce medical resources to patients based solely on when they applied to receive that resource, regardless of their demographic, financial or medical characteristics. 

 

While equitable, there are clear disadvantages involved in the use of this system. Medically, we can expect organs to be inappropriately matched, as the first available organ would have to be given to the person at the top of the waiting list regardless of how compatible it is in a biological sense to the recipient’s immune system. Due to the lower average antigen match that would ensue from a random allocation of organs, graft survival rates would fall, even if patients take greater doses of immunosuppression. The final result would thus be a general waste of organs, which is to be expected, for although using waiting time as a rationing measure is acceptable for homogenous goods, such as hip surgery, when it comes to heterogeneous goods, such as organs with unique antigen combinations, waiting time is a less than desirable allocation policy.

 

Another problem is that no consideration is made of the urgency with which organs are required, with patients who suffer from a sudden, dramatic loss in organ function having to wait behind those previously enrolled patients whose organs are deteriorating at a slower rate than their own organs. For example, in cases of liver failure brought about by toxic poisoning, a person can die within days of infection if no organ is received – if waiting time is used as the prevailing allocation criterion, these people would have no hope of survival as those ahead of them would be first to receive an organ transplant, even though their particular conditions could be managed for longer periods of time through alternate forms of therapy.

 

iii) Priority based on individual medical condition

One way of circumventing the problems associated with allocating organs to patients on the basis of waiting time is to ration organs on the basis of their overall medical status. Here, patients can, depending on the system employed, be given priority on the waiting list depending on whether they are likely to die soon or far into the future from the effects of their disease. 

 

Systems that give priority to sickest patients first are deemed to be equitable since they give those who are at greatest risk of dying very soon a final chance to live that would otherwise not be available. The disadvantage of this system is that very sick patients are less likely to survive past the early stages of their transplant due to their lower overall general health, with patients that do not die having a greater need for retransplantation, which suggests that this system is also not very efficient. By contrast, systems that given priority to relatively healthier patients are deemed to be less equitable since they virtually ensure that very sick patients are bound to die from the lack of an available organ. However, from the perspective of patient survival, they are efficient, as recipients will have a higher graft survival rate and lower need for a retransplant than sick patients. Such a consideration has been borne out by one large American study that concluded that the least sick liver patients on a transplant waiting list had a 1-year post-transplant survival rate of 91% and a 3-year survival rate of 80% against values of 71% and 65% respectively for the sickest patients examined (who had a life expectancy of only a few days) [14].

 

One question that arises here is how much of a delay should be experienced before less sick patients should be allowed to receive an organ transplant, for the healthier they are, the greater will be the number of alternative treatment options available to them. For example, liver patients with hepatitis can receive drug therapy or, if they have certain types of cirrhosis, special types of surgery as a fraction of the cost of a transplant [15], while kidney patients can receive dialysis, with all of these treatment options allowing sick patients to survive with organ failure for a number of years without actually needing a new organ. Eventually, a transplant can be provided during that late period of time in which the patient can no longer benefit from the treatments being received but when there is still enough time for a transplant to help make life satisfactory, which usually happens when life expectancy is less than one year or when the symptoms of disease are unbearable [16].

 

iv) Hybrid allocation systems

In order to achieve a trade-off between the equity and efficiency features of the aforementioned allocation systems, a hybrid system may be developed to assist in the allocation of organs to potential recipients. Here, features of different systems may be incorporated into a single system, with a weighting of values being used to determine, via a points ranking, the place of a patient on a waiting list. This is, for example, the case with several kidney allocation systems used worldwide, where candidates are allocated points on the basis of factors such as their antigen match, waiting time, degree of pre-sensitisation, or status according “special” classification methods. The flaw with these systems is that they operate along the now surpassed principle of cardinal utility, where the relative value of particular candidates depends exclusively on how many points they acquire. The problem here is that there is no discernible or uniform manner in which people qualify for an organ as the position that a person achieves on one ranking system may differ substantially from the position achieved on alternative ranking systems, given the different relative values associated with different allocation criteria [17].

 

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