Organ donation: Opt-out defaults do not increase donation rates, study finds

With the demand for donor organs far outstripping the supply, calls for changes in public policy are growing. An opt-out ('presumed consent') default policy is often seen as a promising approach. This policy stipulates that all adults are automatically considered potential organ donors after their death, unless they explicitly withdraw their consent during their lifetime. In contrast, the opt-in ('explicit consent') system requires potential donors to actively consent to donate their organs after they die. The discussion around implementing an opt-out policy has recently gained traction again in Germany, raising the question of whether such a change in policy would actually lead to an increase in the number of deceased organ donors.

A recent analysis of all member countries of the Organisation for Economic Co-operation and Development (OECD) found no significant difference in deceased donor rates between opt-in and opt-out countries, but significantly fewer living donors -- individuals who voluntarily donate organs, like a kidney, while alive -- in opt-out countries. However, such cross-sectional analyses cannot control for all country-specific factors like health infrastructure, culture, and religious issues -- all of which can influence donation rates.

To address the limitations of prior research, the current study used a longitudinal approach, analyzing changes in deceased donor rates over time in five countries -- Argentina, Chile, Sweden, Uruguay, and Wales -- that had switched from an opt-in to an opt-out default policy. This method provided a more reliable assessment of the impact of opt-out policies by controlling for long-term trends and country-specific factors.

Data was collected from international databases, including the International Registry in Organ Donation and Transplantation (IRODaT) and the Global Observatory on Donation and Transplantation (GODT). Of the 39 countries that had changed from explicit to presumed consent by December 2019, only five could be included in the analysis due to a lack of historical data for changes made before the IRODaT database was launched in 1996 and because presumed consent practices often existed informally prior to formal legislation.

Consistent with previous cross-sectional analyses, the study found that switching the default from opt-in to opt-out did not lead to any increase in organ donation rates in the five countries considered. Moreover, the results indicated that the opt-out default did not cause even a slight upward curve in organ donations: the long-term trend remained the same, showing no change in the rate following the switch. As expected, the results did show a reduction in deceased donations with the onset of the COVID-19 pandemic, with only a slow recovery observed by 2022.

"Simply switching to an opt-out system does not automatically lead to more organ donations," states author Mattea Dallacker, who led the project at the Center for Adaptive Rationality at the Max Planck Institute for Human Development. "Without accompanying measures, such as investments in the healthcare system and public awareness campaigns, a shift to an opt-out default is unlikely to increase organ donations. There is no easy solution to the complex challenge of boosting organ donation rates," she continues.

The study also underscores the crucial role of relatives in organ donation decisions. Even in presumed consent systems, where individuals are considered donors unless they opt out, families are often consulted and can override the presumed consent. Since many people do not talk about their donation wishes with loved ones, presumed consent can lead to uncertainty and hesitation among families, potentially resulting in refusals.

"A possible alternative to the opt-out system is a mandatory choice system," says Ralph Hertwig, Director at the Center for Adaptive Rationality at the Max Planck Institute for Human Development. "This would allow citizens to explicitly register their consent or objection to organ donation, when applying for a driver's license or ID card, for example. This active choice system could prompt people to make an informed decision, which would eliminate the perceived ambiguity about their preference that appears to lead to higher family refusal rates. Good and accessible information about organ donation is essential for informed choice," Hertwig continues.