Opt out organ donation: a rapid evidence review

Information about the review that was undertaken to inform a potential move to a soft opt out system in Scotland.

2. Effectiveness of opt out legislation and systems

This section reviews the evidence on the effectiveness of opt out organ donation legislation and systems. For the purpose of this review, factors associated with effectiveness of opt out systems and legislation includes the number of organs donated and transplanted. Wider effectiveness factors also include changes in attitude (such as being more supportive about donation and behaviours such as greater discussion with families) and awareness/understanding concerning donation.

Registration to be an organ donor is considered, as it remains important because of its association with increased authorisation for donation. It is not treated as a key measure of effectiveness, as in an opt out system not registering a decision is also considered an active decision to donate.

Generally the ultimate aim of organ donation systems is to maximise the number of successful donations to satisfy demand for organs. Increasing awareness of organ donation is associated with increasing numbers of people registering to donate their organs, which is in turn associated with increasing the number of organ transplants. However, increasing awareness and the number of people on a register (for those countries which have one) does not guarantee an increase in the number of transplants. For instance, any increase in the number of people registering as donors is likely to be followed by a significant time lag in donation increases (as those who are newly registering are unlikely to die in the near future). In addition, in many cases those registering may not represent proportionately those who are most likely ultimately to be able to potentially donate. This is as those on registers tend (based on evidence from the UK) to be higher socio economic groups and (in Scotland) particularly in the 30 to 49 years age groups [5] (Optimisa Research, 2014), and do not necessarily mirror proportionately the population who tend to be potential deceased donors. Another challenge to consider is that the context in which people can donate organs, as deceased donors, is relatively small as only 1% of people die in circumstances which would make them eligible to donate. It is clear that more people on a register does not automatically result in more donors. Unless figures are examined over long periods of time, this makes it difficult to robustly conclude that any change is as a result of a policy intervention.

2.1 Comparison studies between opt in and opt out countries in relation to donation and transplantation

This section reviews the body of evidence examining the differences between opt in and opt out countries, in relation to willingness to donate, family authorisation, deceased and living donation.

Opt out organ donation impact on willingness to donate and family authorisation (or willingness to allow donation to proceed)

We explore the association between opt out systems of organ donation on willingness to donate, as this is an important step towards donation. Mossialos et al examined individuals' willingness to donate using survey data from 15 European countries. The study found that those in opt out countries were between 17–29 per cent more likely to report willingness to donate their own organs and 27–56 per cent more likely to authorise the donation of their own relatives' organs compared to respondents living in opt in countries (Mossialos, 2008). Shepherd et al found that family members were much more likely to be willing to authorise the donation of their loved one's organs when they had registered to be a donor themselves (Shepherd & O'Carroll, 2014). The literature regarding family authorisation and opt out could be further developed as only one study was identified. The evidence indicates there is an association between opt out and higher willingness to donate (Mossialos, 2008). A potential causal mechanism for this is discussed in the experimental studies literature (discussed below).

Deceased and living donation and the number of transplants

Deceased donation generally represents the largest source of organs and therefore is particularly important to consider. This section examines the association between opt out and deceased donation/the number of transplants. Shepherd et al (Shepherd; O'Carroll and Ferguson, 2014) conducted a statistical analysis comparing opt in and out countries in terms of both deceased and living donation. The evidence suggests that deceased donor rates (per million population) were higher in opt out than opt in consent countries. However, they found that living donation, which generally represents a smaller source of transplants, was lower in opt out countries. Further evidence to support this was identified by (Bendorf, et al., 2013), who found lower rates of living donation for kidney transplantation in opt out countries. Despite this association, there was limited consideration in the existing literature as to a potential cause and this would benefit from further exploration (Ugar, 2015).

Bendorf (2013) identified that the number of kidneys and livers transplanted from deceased donors was higher in opt out systems, despite lower living donation. Adadie et al examined data from 27 EU countries and found that opt out countries have higher deceased (cadaveric) donation (28% to 32% higher) and kidney transplants (27% to 31%), after controlling for a wide range of factors.

A Welsh Government systematic review compared the number of deceased donors per million population in 2011 across countries (The Welsh Government, 2012). The countries with the smallest number of deceased donors were Bulgaria, Turkey, Cyprus and Greece, all of which had an opt out (presumed consent) organ donation system at the time of the study. However the countries with the greatest number of deceased donors per million population also have opt out systems, such as Portugal, Belgium, Croatia and Spain (The Welsh Government, 2012). Countries with opt out systems therefore did not automatically have high rates of donation. This suggests that opt out systems are not a guarantee of success and highlights the importance of considering opt out as part of wider package of measures/initiatives.

Overall, despite these exceptions, there is a well-established association between opt out and higher rates of deceased donation across a body of evidence (Abadie, A, Gay, S, 2004) (Ugar, 2015) (Shepherd; O'Carroll and Ferguson, 2014) (Bilgel, 2013). There is also some evidence of an association of greater willingness to donate and higher levels of family authorisation of donation. However this is not sufficient to establish a casual impact.

2.2 Evidence from before and after studies

A range of studies have examined countries before and after the implementation of opt out and these further support the association between opt out and higher donation rates and explore a potential causal impact (The Welsh Government, 2012).

Whilst the studies have become increasingly sophisticated at controlling for a wide range of factors that influence organ donation rates (see for example, Shepherd and O'Carroll, 2014), a limitation of the current evidence base is that legislation changes occur concurrently with other factors associated with opt out legislation, such as increased media campaigning and public awareness. The vast majority of the studies make little effort to investigate the impact of any other changes taking place simultaneously. It is therefore nearly impossible to ascertain if it was the legislation or the changes to the system associated with opt out that had the greatest impact.

Impact on proportion registering to be an organ donor

Registration appears to be an important factor in obtaining authorisation. The Organ Donation Taskforce 2008 report found that 90% of families in the UK allowed donation to proceed when a potential donor had joined the ODR compared to 60% when they had not (Organ Donation Taskforce, 2008). The complexity of this relationship is discussed further in section 4.9. This review could not identify any studies examining the impact before and after the introduction of opt out legislation on the numbers of people registering. However, evidence from the Welsh impact evaluation of opt out is encouraging. This found there has been an increase in those registering on the NHS ODR- 34% of the Welsh population were on the ODR in 2014/2015, compared to 36% in 2015/16 (at the time of implementation of opt out) and 38% in 2017/18.

International evidence that examines the impact on donation and transplant numbers

There is a range of evidence which examines the impact of opt out on organ donation and transplant numbers before and after implementation. However, as some studies measure increases in organ donation using different organ types, comparison between studies is difficult.

Rithalia et al's (2009) systematic review examined five before and after studies from three different countries (Austria, Belgium and Singapore), and concluded that there was an increase in deceased donation in all of these studies. The Belgian study is the most relevant as it is the only one where a soft opt out system applies. However, it is limited by the length of time that has passed since the introduction of opt out in 1986. The study identified that kidney transplantation from both deceased and living donors increased from 18.9 to 41.3 per million population per year over a three year period after the change in legislation (Roels, 1991).

Austria and Singapore both have hard opt out systems, where family members do not have a say about the use of a loved one's organs. Comparisons to soft opt out are limited due to the significant differences in authorisation between hard and soft opt out. The Singapore study found that kidney donation increased from 4.7 to 31.3 per million population in the three year period after a change in legislation (Rithalia, et al., 2009). In Austria there was evidence of an increase of 4.6 to 10.1 donors per million population per year in the four years after the introduction of presumed consent. The largest increase in Austria was 27.2 donors per million population (pmp) in the five years after the introduction of infrastructure changes (such as full time transplant coordinators). The study therefore supports the premise that a change to hard opt out legislation can increase organ donation, but continues to support the evidence base that other factors are important. There are limitations generalising these findings to soft opt out legislation.

In the international evidence base, there is variation in the size of increase in deceased donation rates. For instance, some studies report opt out legislation is associated with increases in deceased organ donation rates of 13–18 % (Bilgel, 2013) and 25–30% (Abadie, A, Gay, S, 2004).

Overall, these studies support the notion that changes in systems to an opt out system increase the number of people registering a decision and making people more aware of organ donation policy (this is further supported in the evidence from Wales, discussed below). It is important to note that the literature did not distinguish if this difference was due to the availability of an organ donor register or awareness of organ donation as a whole. There is also firm evidence of an association between opt out and higher deceased donation rates. However, this evidence is insufficient to conclude that opt out legislation in isolation causes higher donation rates. As discussed above, these studies are limited by the concurrent changes that occur to support opt out legislation as part of a wider opt out system. In addition, further research is required to examine the specific impact of soft opt out, as only one study from the international literature was specifically identified which examined this area.

In summary, it is likely that opt out systems and the often concurrent changes are likely to contribute to increases in organ donation. It is challenging to establish if the legislation in isolation leads to increases from the current evidence base, partially because of the other changes that occur concurrently.

2.3 Welsh impact evaluation

Whilst there are key differences (donation rates, proportion of the population on the ODR) between organ donation in Wales and Scotland, the similar context [6] makes it a useful example to examine in detail. The Welsh impact evaluation (The Welsh Government, 2017) examined the impact of opt out legislation and associated system changes three years after implementation. Due to this short timescale, it is challenging to draw any firm conclusions on the overall impact of opt out, but there are some clear changes already apparent.

Public awareness

Overall there was increased awareness of the change to the opt out policy among both NHS staff and the general public. For the public, this has been associated with increased support for opt out. However, awareness had recently decreased, highlighting the importance of maintaining continuous awareness campaigns when implementing opt out.

Whilst this increased awareness is encouraging, it is impossible to tell if this change is a result of opt out legislation or concurrent changes. In addition, it is challenging to establish the long term impact of the opt out system because the evaluation was undertaken only a short time after the implementation of the legislation.

Organ Donor Register ( ODR)

The increased publicity campaigns associated with opt out in Wales are likely to have contributed to the number of people opting out on the ODR (it was possible to opt out on the ODR from six months before the introduction of opt out in Wales). In 2014/2015, 0% of the population opted out of the ODR (as the option was not available). This rose to 5% in 2015/2016 and 6% in 2016/2017 ( NHS Blood and Transplant , 2017). This slight increase suggests that people are able to make an informed decision about whether or not to opt out. Evidence based on approaches to families upon the death of a loved one, have however shown that a significant proportion of others have not opted out via the ODR, but their family members have declared that their relative did not want to donate. This suggests that conversations are often happening in the family, even if individuals are not always recording their decision on the ODR. Awareness of organ donation throughout Wales is, therefore, increasing due to the change in legislation and associated campaigns, which have been associated positively with successful opt out systems (The Welsh Government, 2017).

Family consent

In Wales, analysis from the consent data has shown an increase in the percentage of cases where there was consent for donation (either deemed consent, express consent where the patient was on the ODR or consent from a nearest relative). Consent rates have risen from 44% in 2014 to 65% in 2018.

Number of transplants

Given that organs are allocated UK wide, many organs transplanted in Wales will come from donors in other parts of the UK, so robust conclusions cannot be drawn from any change in transplant numbers in Wales. The Welsh impact evaluation notes that it is too soon to establish any impact on transplantation numbers (The Welsh Government, 2017). Transplantation trends have not been consistent since the implementation of opt out. In 2013/14 the total number of transplants in Wales was 208, at the point of the introduction of the new opt out legislation the number of transplants increased to 214 however the following year the number of transplants decreased to 187 ( NHS Blood and Transplant , 2017).

Summary of Welsh evidence

Although there is strong evidence to suggest an increase in people on the ODR, public awareness and consent rates in Wales, it is impossible to infer that the legislation alone has increased these elements directly. This is likely to be due to a number of additional changes that have also occurred as part of a wider system change, such as awareness raising campaigns. There is evidence to suggest that opt out legislation coupled with the wider changes to the system have impacted positively on many important factors that promote organ donation in Wales. It is crucial to highlight that, due to the modest numbers of organ donors, it is too soon make any conclusions with regards to impact on donation. In this regard, it will be of particular importance to continue to monitor the impact on deceased donation in Wales.

2.4 Experimental studies

As the Welsh Government (The Welsh Government, 2012) identified, there are a range of psychological experimental studies that highlight how opt out may cause an increase in donations. These studies suggest that in an opt out context individuals attribute and perceive less of an individual and personal cost to donating their organs. This evidence indicates that simply framing organ donation as the default increases individuals' willingness to donate (Davidai, 2012) (Dalen, 2014). Whilst these studies provide valuable insights into how opt out may contribute to increased willingness to donate, the findings are of limited value when translating them to the real world due to the artificial settings that these psychological experiments took place in.

2.5 Overall conclusion on international evidence of effectiveness of opt out

International evidence highlights that opt out systems can be effective as part of a wider package of measures (discussed in further depth below). However, overall the body of evidence that examines that opt out legislation in isolation causes increases in donation and transplant lacks robustness and is sparse.

Nevertheless, the broader evidence, particularly from Wales, suggests that a move to an opt out system and the associated changes ( e.g. increased media awareness raising) is likely to impact positively on many important factors that promote organ donation (public awareness, numbers on the ODR and deemed consent/authorisation rates). Legislation is likely to be a catalyst for other beneficial changes in the wider system.


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