In the US, a new patient is added to the waiting list for an organ transplant every 10 minutes.
With an opt-in system, people have to actively sign up to a register to donate their organs after death. In opt-out systems, organ donation will occur automatically unless a specific request is made before death for organs not to be taken.
Prof. Eamonn Ferguson, lead author from the University of Nottingham, UK, acknowledges that because the two systems are reliant on an active decision from individuals, it can lead to drawbacks:
"People may not act for numerous reasons, including loss aversion, effort, and believing that the policy makers have made the 'right' decision and one that they believe in."
However, inaction in an opt-in system can lead to individuals who would want to be a donor not donating (a false negative). In contrast, inaction in an opt-out system can potentially lead to an individual that does not want to donate becoming a donor (a false positive).
The US currently uses an opt-in system. According to the US Department of Health & Human Services, 28,000 transplants were made possible last year due to organ donors. Around 79 people receive organ transplants every day. Unfortunately, around 18 people die every day, unable to have surgery due to a shortage of donated organs.
In or out?
Researchers from the University of Nottingham, University of Stirling and Northumbria University in the UK analyzed the organ donation systems of 48 countries for a period of 13 years - 23 using an opt-in system and 25 using an opt-out system.
The study authors measured overall donor numbers, numbers of transplant per organ and the total number of kidneys and livers transplanted from both deceased and living donors.
They found that countries using opt-out systems of organ donation had higher total numbers of kidneys donated - the organ that the majority of people on organ transplant lists are waiting for. Opt-out systems also had the greater overall number of organ transplants.
Opt-in systems did, however, have a higher rate of kidney donations from living donors. The apparent influence that policy had on living donation rates "has not been reported before," says Prof. Ferguson, "and is a subtlety that needs to be highlighted and considered."
The authors acknowledge that their study was limited by not distinguishing between different degrees of opt-out legislation, with some countries requiring permission from next-of-kin for organs to be donated. The observational nature of the study means that other factors that may influence organ donation remained unassessed.
The researchers state that their results, published in BMC Medicine, show that "opt-out consent may lead to an increase in deceased donation but a reduction in living donation rates. Opt-out consent is also associated with an increase in the total number of livers and kidneys transplanted."
They suggest that although the results could be used in the future to inform decisions on policy, they could be strengthened further through the routine collection of international organ donation information - consent type, procurement procedures and hospital bed availability, for example - which should then be made publicly available.
Prof. Ferguson suggests that future studies could also analyze the opinions of those who have to make the decision to opt in or opt out:
"Further research outside of this country-level epidemiological approach would be to examine issues from the perspective of the individual in term of beliefs, wishes and attitudes, using a mixture of survey and experimental methods."
"By combining these different research methods researchers can develop a greater understanding of the influence of consent legislation on organ donation and transplantation rates," he says.
The authors note that countries using opt-out consent still experience organ donor shortages. Completely changing the system of consent is, therefore, unlikely to solve such a problem. They suggest that consent legislation or adopting aspects of the "Spanish Model" could be ways to improve donor rates.
Spain currently has the highest organ donation rate in the world. The Spanish utilize opt-out consent, but their success is credited by experts to measures such as a transplant co-ordination network that works both locally and nationally, and improving the quality of public information available about organ donation.
Recently, Medical News Today ran a spotlight feature on whether animal organs should be farmed for human transplants. Could this be a solution to the organ shortage, or this a problem to be addressed through changes to organ donation policy?