Tuesday, 28 October 2025
New research has shown opt-out organ donation policies may reduce living organ donors, leaving systems overall no better supplied with lifesaving organs.
Opt-out organ donation policies which enrol everyone into post-mortem donation programmes by default unless people choose to opt out are being adopted by an increasing number of countries as a way to increase the supply of desperately needed organs.
Researchers from the 糖心原创 were part of an international team that analysed data from 24 countries from 2000 to 2023 and found that although opt-out policies did increase deceased organ donors by a small, non-significant amount of 7%, the number of living donors dropped significantly by 29%. Overall, the opposite effects of deceased and living donors on the supply of organs result in no additional benefit in donor numbers from moving to an opt-out policy.
The researchers suggest this effect occurs because the transition to an opt-out system alters the way people perceive the supply of organs, leading them to believe the move to an opt-out system solves the supply shortage. The study confirmed this across a number of experiments on over 5,000 participants in Germany (opt-in) and Austria (opt-out), demonstrating that there is a crowding-out effect that primarily affects so-called “altruistic donations" to acquaintances and strangers, rather than donations to family members.
The most needed organ for transplant in the UK is the kidney, with over 5,500 people currently on the waiting list, and they are the most transplanted organ, especially from living donors. Living donors account for more than 40% of all organ donations in England so the significant reduction in living donors is a major concern. Living organ donations, particularly for kidneys, are also generally more successful, with an average 10-year survival rate of 90%, compared with 75% after a deceased donor transplant.
We found a hidden negative effect of opt-out policies that changes people鈥檚 perception of the supply of organs, as they believe this solves the problem and the demand for organs will be met. This has the knock-on effect of reducing the number of people willing to be living donors, as they believe the need is no longer there. This could have a particular impact on kidney donations, which we know are in high demand and are more successful from living donors.
He continues:
“Opt-out policies are proposed for use in other areas of health-care provision like vaccination, and as such, potential crowding-out effects need to be considered in these areas as well.”
In England, the opt-out system was introduced by the Organ Donation (Deemed Consent) Act 2019 and officially came into force on 20 May 2020. The findings reveal the unintended consequences of a public policy nudge and suggest that policymakers should consider potential crowding-out effects when implementing opt-out organ donation systems.
“Changing to the opt-out system isn’t having the intended effect of dramatically increasing the number of organ donors that was hoped for.” adds Professor Ferguson, “What is really needed is investment in education and awareness around organ donation, starting with children in school. As a society, we need to discuss it more so that people can make informed choices about becoming a donor. One way, for example, to trigger discussions about organ would be with pieces of public art.”
The paper “Crowding out Effects of Opt-out Defaults: Evidence from Organ Donation Policies” has been published today in PNAS-Nexus.
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More information is available from Professor Eamonn Ferguson on Eamonn.ferguson@nottingham.ac.uk
Notes to editors:
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