Comparative donation systems and PMP metrics

Comparative donation systems is the study of how different countries organize, regulate and fund deceased and living organ donation, and of why donation rates differ so widely between them. The standard metric for comparison is the per-million-population (PMP) rate, most commonly deceased organ donors per million population (dpmp), which normalizes a country's donor count by its population so that systems of different sizes can be compared.[1][2] A central, well-supported finding of this literature is that the difference between "opt-in" and "opt-out" (presumed-consent) law does not, by itself, explain the large variation in donation rates; the dominant drivers are instead organizational capacity, donor identification, in-hospital coordination, trained staff, ICU and transplant infrastructure, and the way families are approached.[3][4][5]

The PMP metric

The deceased donors per million population rate is the most widely used international comparison, reported by the Global Observatory on Donation and Transplantation (GODT), a joint WHO/ONT effort, and the associated IRODaT registry.[1][2] PMP can be reported for actual (utilized) deceased donors, for total transplants, or for living donors, and definitions of a "donor" (for example, donors from whom at least one organ was recovered or transplanted) vary, so cross-source comparisons require care.[1][2] PMP is a rate, not a measure of need or efficiency; a country's PMP reflects its population age structure, mortality patterns (e.g., rates of fatal trauma and stroke), clinical practices around end-of-life care and brain-death determination, and its donation infrastructure, in addition to consent law.[2][3]

Wide variation between countries

Deceased-donation PMP rates differ several-fold among high-income countries. As of GODT/IRODaT data for 2023, Spain led the world at roughly 49 deceased donors pmp, with the United States close behind at about 48 pmp; other high performers (Portugal, Belgium, Croatia, France and others) ranged broadly lower, and many countries reported rates in the single digits or low teens.[2][6] Notably, the two highest-rate countries, Spain and the United States, differ in consent law (Spain has a presumed-consent statute; the United States is opt-in), which is itself evidence that the consent default is not the decisive variable.[2][3][4]

Consent law vs organizational capacity

Countries use two broad consent models: opt-in, where a person must affirmatively register or be authorized for donation, and opt-out / presumed consent, where a person is treated as a donor unless they have registered an objection.[3][5] Most opt-out systems in practice are "soft", meaning families are still consulted. See consent models: opt-in vs opt-out.

The evidence on whether opt-out raises donation rates is the most studied question in this field, and the consistent conclusion of systematic reviews is cautious:

• A widely cited systematic review (Rithalia et al., BMJ 2009) found that, while presumed-consent countries tended to have higher donation rates, "presumed consent alone is unlikely to explain the variation in donation rates", and that donor availability, transplant infrastructure, and social, legal and economic factors also play a role whose relative importance is unclear.[4] The companion NIHR Health Technology Assessment review reached the same conclusion: an association exists, but causation cannot be isolated, and infrastructure or organizational changes may produce greater gains than legislative change.[5]
• The Spanish experience is the strongest single piece of evidence. Spain's presumed-consent law was enacted in 1979, but its donation rate did not rise for a decade; the increase began only after the organizational Spanish Model was built under the ONT from 1989, demonstrating that the same law produced very different results depending on whether the organizational system existed.[7]
• The United Kingdom's moves to deemed consent (Wales 2015, England 2020, Scotland 2021) likewise produced mixed and non-uniform effects on consent rates, with family involvement and specialist-nurse infrastructure remaining decisive. See NHS Blood and Transplant and UK deemed consent.[8]
• More recent analyses, including behavioral and econometric studies, reinforce that changing the default to opt-out, without corresponding investment in donor-identification and coordination infrastructure, yields limited or no increase in donors, and can even leave rates unchanged.[9]

The neutral synthesis is therefore that organizational capacity, not the consent default alone, drives deceased-donation rates. Countries that built strong in-hospital coordination, systematic donor detection, ICU capacity and trained donation staff, whether under opt-in (e.g., the United States) or opt-out (e.g., Spain) law, achieve the highest PMP rates, while opt-out laws adopted without that infrastructure produce modest gains at best.[3][4][5][7]

Other dimensions of comparison

Beyond consent law, comparative analyses consider: the balance of deceased versus living donation (some countries, historically including several in Asia, rely heavily on living donors); the use of donation after circulatory death versus brain-death pathways; national versus multinational allocation (e.g., Eurotransplant); funding and reimbursement of donation activity; and the legal determination of death. These structural features interact, which is a further reason that single-variable comparisons (such as opt-in vs opt-out) are misleading.[2][3]

See also

• Consent models: opt-in vs opt-out
• The Spanish Model and the ONT · NHS Blood and Transplant and UK deemed consent · Eurotransplant
• Organ donation gap / national transplant waiting list
• Donation after brain death (DBD) · Donation after circulatory death (DCD)

References

• Global Observatory on Donation and Transplantation (GODT), WHO-ONT collaboration. International data on donation and transplantation activity (PMP definitions). https://www.transplant-observatory.org/
• International Registry in Organ Donation and Transplantation (IRODaT). Donation and transplantation rates by country (deceased donors pmp). https://www.irodat.org/
• Vanholder R, Domínguez-Gil B, Busic M, et al. Organ donation and transplantation: a multi-stakeholder call to action / determinants of donation rates (organizational drivers). Nat Rev Nephrol. 2021;17:554-568. https://www.nature.com/articles/s41581-021-00425-3
• Rithalia A, McDaid C, Suekarran S, Myers L, Sowden A. Impact of presumed consent for organ donation on donation rates: a systematic review. BMJ. 2009;338:a3162. PMID 19147479; PMC2628300. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2628300/
• Rithalia A, McDaid C, Suekarran S, et al. A systematic review of presumed consent systems for deceased organ donation. NIHR Health Technology Assessment. 2009;13(26). NBK56888. https://www.ncbi.nlm.nih.gov/books/NBK56888/
• GODT / IRODaT 2023 deceased-donor rates (Spain ~49 pmp; United States ~48 pmp); Government of Spain transplant figures (La Moncloa, 2025). https://www.lamoncloa.gob.es/lang/en/gobierno/news/paginas/2025/20250116-transplant-figures.aspx
• Matesanz R, Domínguez-Gil B, Coll E, et al. How Spain reached 40 deceased organ donors per million population. Am J Transplant. 2017;17(6):1447-1454. doi:10.1111/ajt.14104. https://www.sciencedirect.com/science/article/pii/S1600613522250060
• Madden S, et al. The effect on consent rates for deceased organ donation in Wales after the introduction of an opt-out system. Anaesthesia. 2020;75(9):1146-1152. PMC7496553. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496553/
• Arshad A, Anderson B, Sharif A. Comparison of organ donation and transplantation rates between opt-out and opt-in systems. Kidney Int. 2019;95(6):1453-1460. PMID 30982675. https://www.kidney-international.org/article/S0085-2538(19)30298-4/fulltext