To examine the impact of presumed consent legislation on organ donation and to review data on attitudes to presumed consent among the public, professionals and any other stakeholders.
Eight electronic databases (MEDLINE, MEDLINE In-Process, EMBASE, CINAHL, PsycINFO, HMIC, PAIS International and OpenSIGLE) were searched from inception to January 2008. Supplementary internet searches were also performed.
A systematic review of studies comparing donation rates in a single country before and after the introduction of a presumed consent law or in countries with and without presumed consent systems. The methodological quality of these studies was assessed and a narrative synthesis of results undertaken. Surveys of attitudes towards presumed consent legislation were also included.
Over 2000 potentially relevant citations were identified, of which 13 studies met the inclusion criteria for the primary objective and 13 for the secondary objective. For the primary objective, eight studies were between-country comparisons and five were before-and-after studies. Four of the between-country comparisons were of sufficient methodological quality to provide reliable results. In all four studies presumed consent law or practice was associated with increased rates of organ donation, ranging from an increase of 2.7 donors per million population (pmp) in one study to 6.14 donors per million in another, and an increase of between 20% and 30% in two other studies. Factors other than presumed consent that had an impact on organ donation rates were mortality from road traffic accidents and cerebrovascular accident, the transplant capacity of a country, gross domestic product per capita and health expenditure per capita, religion, education, public access to information and a common law legal system. The five before-and-after studies represented three countries, all of which reported an increase in donation rates following the introduction of a presumed consent system (Austria, from 4.6 to 27.2 donors pmp over a 5-year period; Belgium, increase in kidney donation from 10.9 to 41.3 pmp during a 3-year period; Singapore, increase in kidney procurement from 4.7 to 31.3 per year in the 3 years after the change in legislation). There was very limited investigation of any other changes taking place concurrently with the changes in legislation across this set of studies. Of the 13 studies addressing the secondary objective, eight were surveys of the UK public, four were from other countries and one was an international survey of health professionals. There was variation among the UK surveys in the level of support for presumed consent, with surveys conducted before 2000 reporting the lowest levels of support (28-57%). The most recent survey by YouGov in 2007 reported that 64% of respondents supported a change to presumed consent.
Presumed consent alone is unlikely to explain the variation in organ donation rates between different countries. A combination of legislation, availability of donors, transplantation system organisation and infrastructure, wealth and investment in health care, as well as underlying public attitudes to and awareness of organ donation and transplantation, may all play a role, although the relative importance of each is not clear. Further reviews could investigate the factors likely to modify donor rates, such as procedures for family involvement. The way in which families of any potential donor are approached is likely to be an important factor and a review of qualitative research examining the experience of relatives in this context would be useful.