Organ donation, transplantation and consent

Organ donation and transplantation operate within a complex ethical and legal landscape that balances the urgent need for life-saving organs against the autonomy of the individual and the public interest. In the United Kingdom, the current legal framework relies on an explicit or informed consent system. This model requires that individuals authorise organ removal after death by carrying a donor card or joining a national registry. This approach contrasts with systems of presumed consent, where individuals are considered donors unless they have explicitly opted out. The UK Organ Donation Taskforce was established in 2006 with the specific task of identifying barriers to donation and making recommendations for increasing organ donation and procurement within the current legal framework. The taskforce’s recommendations included establishing a UK-wide organisation to identify and allocate organs, doubling the number of transplant coordinators, and having an organ donation “champion” in each hospital trust. These structural changes aim to improve the processes for identifying potential donors and the monitoring of donation activity in all hospitals. ^[1]

The ethical debate often centres on whether shifting to presumed consent increases donation rates. A systematic review sought empirical studies that examined the impact of having a system of presumed consent on organ donation rates. Eligible studies were those which compared organ donation rates before and after the introduction of presumed consent or where organ donation rates were compared in countries with and without systems of presumed consent. Twenty-six studies met the inclusion criteria for this review. Of these, five assessed organ donation rates before and after the introduction of presumed consent legislation in a single country. Eight compared organ donation rates in countries with presumed consent systems with rates in countries with explicit or informed consent or similar systems. Thirteen surveys addressed attitudes towards presumed consent. The eight studies comparing countries were based on secondary analyses of published data. Therefore, any relation found between presumed consent and organ donation rate is associative and cannot show whether the effect was directly attributable to the intervention. ^[1]

Although four robust studies suggest that presumed consent law was associated with increased organ donation rates, other explanatory factors were associated with variation in donation rates between countries. Organ donation would be expected to depend to some extent on the availability of potential donors. In three studies where it was considered, mortality from road traffic accidents showed a significant association with donation rate. In one study, this was the only factor that had a significant association with donation rates. Blood donation rate was investigated as an indicator of social preferences towards organ donation in one study, and it showed a positive though non-significant association with organ donation rates. The review found four good quality studies comparing organ donation rates between countries with and without systems of presumed consent. Each study examined the association between presumed consent and organ donation rates in mainly European countries between 1990 and 2002. All four found an association between presumed consent legislation and higher organ donation rates, and in three this was statistically significant. ^[1]

The process of deceased donation is heavily influenced by the consent of next of kin, even when the deceased had previously registered their wishes. The most common reason why organs for transplantation are not obtained from patients after confirmation of brain stem death on an intensive care unit in the United Kingdom is the refusal of consent by the patient’s relatives. A recent audit of all deaths in 341 intensive care units in the UK over a 24 month period showed that 41% of the relatives of potential organ donors denied consent for donation. Although in the UK the Human Tissue Act 2004 prioritises the wishes and consent of the potential organ donor over his or her relatives, it is almost inconceivable that organs would be retrieved from a deceased donor against the wishes of relatives. Consent for donation is therefore likely to remain an important step in organ procurement for the foreseeable future. This highlights a critical ethical tension: while the law respects the donor’s autonomy, the practical reality of clinical care requires the cooperation of the family, making the consent process a shared decision rather than a purely legal one. ^[2]

There are several modifiable factors correlated with consent rates for organ donation. The ACRE study was based on the assumption that organ donation is of sufficient benefit to organ recipients and to society generally that it is appropriate to test techniques to maximise organ donation consent rates using a study design that required a waiver of consent. This assumption requires wider debate and discussion. The ethical justification for such studies rests on the principle that the societal benefit of saving lives outweighs the minor intrusion of the research process, provided that the techniques do not coerce or manipulate the decision-making process of the family.

Living donation presents a different ethical framework, primarily governed by the principle of non-maleficence and the voluntary nature of the gift. While the provided passages focus heavily on deceased donation and policy, the ethical principles of autonomy and beneficence apply equally to living donors. The global context of organ transplantation also includes serious ethical violations. Legally available organs for transplantation represent an estimated 10% of the global organ transplant need. Trafficking in persons for the purpose of organ removal and organ trafficking for transplantation represent two separate criminal activities under international legal frameworks. These activities prey most on individuals in situations of acute vulnerability, such as undocumented migrants, refugees, detainees, and people living in hardship poverty. Organ trafficking refers to the illicit removal and sale of organs, while trafficking in persons for organ removal involves the recruitment and exploitation of individuals for that purpose. While data are incomplete due to the clandestine nature of the criminal activity, organ trafficking has been reported in North Africa, South and South-East Asia, Central America, and Europe. ^[6]

The allocation of organs is another critical ethical component. In the United States, adult organ allocation is a subject of extensive literature review. Exclusion criteria for such reviews typically include multi-organ transplantation, re-transplantation, pediatric organ transplantation, and organ allocation outside of the United States. This focus on specific populations and geographies highlights the need for context-specific ethical guidelines. The disparity between the 10% of global need met by legal organs and the prevalence of trafficking underscores the urgency of ethical oversight in all jurisdictions. Medical students must understand that consent is not merely a bureaucratic step but a profound ethical interaction that respects the dignity of the deceased and the grief of the family, while simultaneously serving the greater good of saving lives through transplantation.

Organ donation consent systems fall into two broad categories. In an opt-in system, individuals must actively register their willingness to donate organs after death; without such registration, donation does not proceed. In an opt-out (presumed consent) system, a dead person is considered to be an organ donor unless the person made known his or her opposition to this before death. Countries vary in how these laws function in practice, and the terms “hard” and “soft” characterise how much emphasis is placed on relatives’ views. ^[1]

Spain, Austria, and Belgium have introduced presumed consent legislation. Spain’s law is “soft”—doctors actively check that relatives do not object. Austria’s is relatively “hard”—recovery proceeds unless the deceased was known to have objected, and relatives’ views are not actively sought. In the UK, the chief medical officer supported a presumed consent system, and the Organ Donation Taskforce investigated the impact of an opt-out system, publishing recommendations in November 2008. ^[1]

Evidence on whether opt-out systems increase donation comes from five before-and-after studies and eight between-country comparisons. Two studies reported a 20–30% increase in organ donation, one reported 2.7 more donors per million population, and one reported 6.1 more donors per million population. Five before-and-after studies showed increased donation rates following introduction of presumed consent. However, presumed consent alone is unlikely to explain variation between countries; legislation, donor availability, infrastructure, wealth, health investment, and public attitudes all play a part, though their relative importance is unclear. Even when other factors are accounted for, presumed consent is associated with increased rates—yet this does not prove that introducing such legislation per se will increase donation. ^[1]

Public attitudes matter. Recent UK surveys show support for presumed consent, though results vary with survey methods. About a third of relatives who refused donation, when interviewed later, suggested they would not make the same decision again, whereas few consenting relatives regretted their decision—suggesting many refusals are not based on deeply held views^[1]. Trained requestors increase consent rates: a systematic review identified 11 observational studies showing this, and “collaborative requesting”—where the patient’s clinician and a donor transplant coordinator make the request jointly—is one technique^[1]. ^[2]

Organ donation after death occurs in two distinct clinical scenarios, each with different legal, ethical and practical implications. Understanding the difference is essential for any doctor who may be involved in identifying a potential donor or approaching a family.

Brain death donation (donation after brain stem death, DBD) refers to donation from a patient who has been declared dead using brain stem death criteria. In the UK, this diagnosis is made by two senior doctors using strict clinical tests, performed twice, after excluding reversible causes of coma. Once brain stem death is confirmed, the patient is legally dead even though the heart continues to beat and the chest rises and falls with mechanical ventilation. Organs are retrieved in an operating theatre while the heart is still beating, which optimises organ quality. In a large UK-wide audit, 2754 patients were declared dead by brain stem death criteria. Among relatives approached for donation in this setting, the consent rate was 59%. Of those who consented, solid organs were actually obtained in 86% of cases, close to the 90% reported previously in the UK. ^[2]

Circulatory death donation (donation after circulatory death, DCD) occurs when death is confirmed by the irreversible cessation of cardiac output and circulation, rather than by brain stem testing. This typically follows a planned withdrawal of life-sustaining treatment in a patient with a catastrophic brain injury who does not meet brain stem death criteria. After the heart stops, a period of observation (usually 5 minutes of asystole) is required before death is declared and retrieval can begin. Because organs suffer a period of warm ischaemia between circulatory arrest and cold perfusion, DCD organs are generally of lower quality than DBD organs, and some organs (such as the heart) are rarely used from DCD donors.

The distinction matters for consent. In DBD, the patient is already dead when the family is approached, so the discussion is about organ retrieval, not about ending life. In DCD, the decision to withdraw treatment is made separately from the decision to donate, and the two must never be conflated in the family conversation.

Allocation fairness concerns how a scarce supply of donated organs is distributed among a waiting list of potential recipients. Because demand vastly outstrips supply, every transplant system must decide who gets priority. The ethical challenge is that the criteria used to rank patients inevitably reflect value judgements about what makes a fair allocation – and these judgements are not always transparent or consistent.

Modern allocation systems increasingly rely on quantitative risk scores to rank candidates. Examples include the Model for End-Stage Liver Disease (MELD) score for liver transplantation, the Kidney Donor Profile Index (KDPI) and Estimated Post Transplant Survival (EPTS) for kidneys, the Lung Allocation Score (LAS), and the Heart Tier System. These scores aim to prioritise patients who are most urgently ill or most likely to benefit. However, a systematic review of 127 records found a marked lack of ethical uniformity across these scores, because each was developed independently for its own organ type. The review concluded that current scores lack explicit goals and transparent reasoning behind their variable selection, and that some scores may be statistically satisfactory but carry significant ethical flaws. ^[4]

A central question is whether better outcomes alone should determine prioritisation. The review explicitly asks: if better predictability justifies the use of risk scores, then how should variables be selected to ensure fairness and equity while maximising outcomes? The concern is that a score may predict survival well but encode bias. For example, although OPTN policies prohibit organ allocation based on race, ethnicity, or socioeconomic status, the transplantation referral and evaluation processes may be biased against these factors; Black patients are significantly less likely than white patients to be considered suitable transplant recipients and referred for transplant evaluation, even if they express interest in receiving a transplant. This shows that inequity can arise before allocation even begins – at the point of referral and listing. ^[4]

The review also notes that it is insufficient to conclude that because a score predicts some outcome, that particular score is justified in its implementation for organ allocation. Clear and consistent guidelines for the development and validation of scores across solid organs must be developed and adopted to provide transparency. In conclusion, although organ-specific risk assessment may be necessary given the differential availability of therapy for different end-stage organ diseases, the underlying ethical framework of each risk score and allocation system should be assessed periodically to minimise ambiguity and subjective biases. ^[4]

Xenotransplantation—the transplantation of living cells, tissues, or organs from one species to another—has long been proposed as a solution to the chronic shortage of human organs for transplantation. The demand for human organs constantly outstrips the altruistic supply, and even in regions with "presumed consent" and optimized procurement programs (e.g., Spain), organ shortages persist. This shortage is the driving force behind both the scientific pursuit of xenotransplantation and the illicit global trade in human organs. ^[6]

The science of xenotransplantation has made considerable progress, particularly in the realm of non-life-supporting heart xenotransplantation. However, life-supporting heart xenotransplantation in non-human primates (NHPs) remains difficult. Until 2018, the longest survival time of life-supporting heart transplantation in pig-to-NHP cases was only 57 days. Langin et al. subsequently modified their procedure and reported a survival time of more than 6 months in cases of life-supporting heart xenotransplantation in baboons. Two steps were crucial to prolong the survival of functional xenografts in baboons: first, non-ischemic porcine heart preservation was performed instead of cold static storage; second, detrimental xenograft overgrowth was restricted by a drug called temsirolimus. Among the various types of xenotransplantation, the transplantation of islet cells is the only form of cell or tissue transplantation that has seen clinical implementations. ^{[3] [5]}

The ethical landscape of xenotransplantation extends beyond the patient. As any member of society is potentially at risk of acquiring a xenogeneic infection, the informed consent of the patient who shall receive the xenograft is not enough: xenotransplantation becomes a societal matter. Hence, a "collective informed consent" or a "community consent" have been suggested. As the community at risk is the global community, xenotransplantation also becomes a matter of global justice. ^[5]

The relationship between xenotransplantation and organ trafficking is complex and uncertain. Some have suggested that the rise of xenotransplantation will reduce or even end human organ trafficking. Ekser and colleagues stated that, "Illegal organ trafficking and the use of organs from executed prisoners will be obviated". Solbach wrote, "Increased xenotransplantation would also help reduce illegal human organ trafficking and the incidence of potentially life‐threatening complications from living human donation". The argument that xenotransplantation will decrease or eradicate human organ trafficking is based on forecasted inverse supply and demand relationships: if the supply of organs from xenotransplantation increases, there will be a corresponding decrease in human organ trafficking. This seems theoretically plausible, for if xenografts are abundantly available there may be little reason for illicit trade in human organs. ^[6]

However, this model relies on a series of complex assumptions. Significant uncertainty remains, additional problems may arise with the growth of xenotransplants, and continued vigilance will be required. Given that most organ trafficking is concentrated in low- and middle-income countries (LMICs), this creates a paradox: the proposed solution (xenotransplantation) may not be available where this problem is most acute. Less affluent patients globally would continue to wait for human organs. Even with a sufficient xenograft supply, demand for illicit organs might persist due to economic, non-economic and systemic factors (e.g., religious barriers to pig organ acceptance; views of xenograft inferiority to allografts; payments for organs), limiting the impact of xenotransplantation on organ trafficking. This might worsen the desperation that fuels the current black market, especially as the global burden of noncommunicable diseases (e.g., hypertension, diabetes) driving organ failure continues to rise, driving the need for organ transplantation and intensifying pressure on the system. ^[6]

When considering organ donation, transplantation, and consent, several common pitfalls arise in both clinical practice and ethical reasoning. One of the most significant is the oversimplification of presumed consent as a binary variable. Although presumed consent is not a binary variable, it has been treated as such in between-country comparisons. Countries vary in the nature of their legislation and how the legislation is interpreted. Of key importance is the extent of consultation about donation with relatives of the deceased. This was partly addressed in one study that compared countries on the basis of how legislation was implemented in practice, rather than the actual legislation in place. Regardless of the legislative system, the procedures for contact with relatives of newly deceased people are likely to be important determinants in whether consent is given. ^[1]

A second pitfall is the uncritical interpretation of before-and-after studies of presumed consent legislation. Before and after studies have the benefit of exploring the experience of individual countries but, because it is an uncontrolled study design, it is not possible to rule out the influence of other known or unknown factors influencing donation rates. All five studies, which represented the experience of three countries, found an increase in organ donation rates following the introduction of presumed consent legislation. However, attributing this increase solely to the legislation would be a mistake, as other factors may have contributed. ^[1]

A third pitfall is overlooking the role of transplant coordination infrastructure. The extent and efficiency of a country's transplant coordination might also be expected to influence organ donation rates. In the one study that considered it, transplant capacity (defined as the number of transplant centres per million population) was positively associated with higher donation rates and within the statistical model it was the factor with the greatest predictive strength, greater than presumed consent practice, religion, and education. Students and clinicians alike often focus on consent legislation while neglecting the practical infrastructure that may matter more. ^[1]

A fourth pitfall is assuming that public opinion uniformly favours presumed consent. With the exception of one survey from Belgium, where there is presumed consent legislation, most respondents in surveys from outside the UK seemed opposed to presumed consent. This highlights the importance of understanding local cultural and social contexts rather than assuming a universal preference. ^[1]

A fifth pitfall, specific to xenotransplantation, is the assumption that informed consent from the individual patient suffices. As any member of society is potentially at risk of acquiring a xenogeneic infection, the informed consent of the patient who shall receive the xenograft is not enough: xenotransplantation becomes a societal matter. Failing to engage the broader community in consent processes is a serious ethical oversight.

A sixth pitfall is the naive belief that xenotransplantation will simply eliminate organ trafficking. While successful xenotransplantation may reduce organ trafficking, significant uncertainty remains, additional problems may arise with the growth of xenotransplants, and continued vigilance will be required. The assumption that increased supply automatically eradicates the black market ignores the complex economic, non-economic and systemic factors at play.

In practice, organ donation systems vary widely across countries, and the implementation of presumed consent legislation has been studied for its effects on donation rates. All five studies, which represented the experience of three countries, found an increase in organ donation rates following the introduction of presumed consent legislation. However, these before-and-after studies are uncontrolled, and it is not possible to rule out the influence of other known or unknown factors influencing donation rates. For example, Spain is often cited as a success story with optimized procurement programs, yet even there organ shortages persist. This illustrates that presumed consent alone is not a panacea.

The practical importance of transplant coordination cannot be overstated. In the one study that considered it, transplant capacity (defined as the number of transplant centres per million population) was positively associated with higher donation rates and within the statistical model it was the factor with the greatest predictive strength, greater than presumed consent practice, religion, and education. This suggests that investment in infrastructure and coordination may yield greater returns than legislative change alone.

Regarding xenotransplantation, clinical implementation remains limited. Among the various types of xenotransplantation, the transplantation of islet cells is the only form of cell or tissue transplantation that has seen clinical implementations. This is particularly relevant for patients with type 1 diabetes mellitus (T1DM), who are potential candidates for islet xenotransplantation. In interviews with potential candidates, one patient remarked, "I was feeling way better due to the insulin, therefore I didn't think about it" (Mrs. F). This illustrates that patient attitudes are shaped by their current treatment experience, which has implications for how xenotransplantation might be received. ^[5]

In the realm of heart xenotransplantation, progress has been made but remains experimental. Until 2018, the longest survival time of life-supporting heart transplantation in pig-to-NHP cases was only 57 days. Langin et al. modified their procedure and reported a survival time of more than 6 months in cases of life-supporting heart xenotransplantation in baboons. Their protocol included non-ischemic porcine heart preservation instead of cold static storage, and the use of temsirolimus to restrict detrimental xenograft overgrowth. These advances, while promising, have not yet translated into routine clinical practice.

The ethical framework for xenotransplantation in practice must account for its societal dimension. As any member of society is potentially at risk of acquiring a xenogeneic infection, the informed consent of the patient who shall receive the xenograft is not enough: xenotransplantation becomes a societal matter. Hence, a "collective informed consent" or a "community consent" have been suggested. As the community at risk is the global community, xenotransplantation also becomes a matter of global justice. This means that regulatory frameworks must extend beyond individual patient-doctor relationships to include broader public engagement and international cooperation.