Table 4 Included studies—main findings

Alsaied Qatar 2012 [10]

To identify and assess the level of knowledge and attitudes of health care professionals

(HCP) in Qatar toward organ donation and transplantation

46.8% physicians believe BD equivalent to death, the figure for nurses was 18.2% and that for EMS technicians was 47.5%. Less than half the subjects were aware that brain death was legal in Qatar

Burroughs USA 1998 [13]

To examine the psychological consequences of consenting or refusing donation of the organs or tissue of a dying family member

Families who were satisfied with their decision to donate were more likely to have understood brain death or had it explained to them as compared to non-donors or non-satisfied donors. Individuals who felt pressured were less likely to donate

Camut France 2016 [50]

To investigate the feelings and the acceptance in healthcare professionals of non-therapeutic intensive care for brain death organ donation and to assess their training needs

8.3% of HCW do not regard brain death as true death. Overwhelming majority support non-therapeutic Intensive Care in the context of organ preservation for donation. However, > 75% favour advance patient's consent and approval of family

Cohen Israel 2008 [25]

Whether attitude to brain death of health care professionals influences the organ retrieval process

78.9% had a positive attitude towards brain death which translated into more comfort with various practical aspects of donation process

DeJong Canada 2013 [43]

To determine public opinion regarding whether DCDD donors are dead at the time of organ retrieval

68% of respondents believed death had occurred after 5 min of absent circulation with prior DNR in place. In the absence of DNR that figure dropped to 53%. 49% said dead donor rule should be discarded

Dhanani et Canada 2012 [40]

To describe the manner in which Canadian adult and paediatric intensive care physicians report death determination after cardiac arrest

Only 39% of surveyed physicians use various combination of clinical tests conforming to ANZICS definition of death. About two-third of respondents had heard about autoresuscitation and 37% had seen one

Dubois et al. USA 1999 [23]

To assess views of medical personnel regarding brain death and organ retrieval and related issues

Only 25% agreed to declare a person dead and retrieve organs prior to the death of brain if heart and lungs have stopped functioning for a few minutes. 62% supported the claim that higher brain death is death and 61 and 63% of participants supported organ retrieval from anencephalic patients and from higher brain death respectively

ElSafi et al. Saudi Arabia 2017 [26]

To explore the knowledge and attitudes toward organ donation and transplantation among 1st-year pre-clinical students before their taking any health science courses compared with students taking more advanced courses

Majority do not support deceased organ donation and 49.9% mentioned mistrust of the medical staff regarding brain death diagnosis as a reason

Floden et al. Sweden 2011 [9]

To present data on Swedish ICU nurses’ attitudes to brain death and organ donation and to test a questionnaire designed to explore these issues in terms of validity and reliability

48% of nurses trusted brain death diagnosis without confirmatory cerebral angiography, whether this reflects Knowledge gap or lack of trust it is unclear

Goudet France 2013 [44]

To determine the ethical acceptability for a large population of hospital personnel of organ donation following uncontrolled cardiac death

65% of the respondents thought that care givers might find it hard to reconcile the two aims of prolonging life vs organ preservation in the setting of uncontrolled cardiac death. 56% of these HCW find some aspect of uncontrolled DCDD problematic

Hart et al. USA 2012 [45]

To identify factors related to critical care physicians’ and nurses’ willingness to help manage potential donors after circulatory determination of death, and to elicit opinions on the presence of role conflict caring for donors after circulatory determination of death and its impact on end-of-life care

Minorities of physicians (14.7%; 95% CI 12.0–17.4) and nurses (14.3%; 95% CI 11.0–17.6) believed that managing DCDD would create professional role conflicts

Health professionals survey Canada 2006 [51]

To develop an understanding of Canadian healthcare professionals’ awareness, attitudes, and beliefs surrounding organ and tissue donation;

To discover Canadian healthcare professionals’ views on donation after cardiocirculatory death including family/legal/ethical issues

Surveyed health care professionals found it unacceptable to perform medical procedures or administer medications to the patient before or immediately after circulatory death, with the sole intention to preserve organs for transplantation without prior consent

Honarmand et al. 2020 [59]

Attitudes of HCPs involved in OD and transplantation towards cardiac transplantation via DCDD

In the open-ended responses concerns were expressed about certainty of death and implications of restarting the heart after death declaration

22% of respondents had concerns about interruption of cerebral vasculature during the NRP and 2/3rd of the respondents felt ethical concerns were a significant barrier in implementation of NRP protocol

Hu China 2015 [55]

To assess the knowledge, attitudes, and willingness toward organ donation among health professionals in China

68.9% thought brain death was a reasonable criterion to judge death

Hyde et al. Australia 2011 [31]

Examined negative donation perceptions and explored any potential differences in these beliefs in a sample of people who self-identified as donors (want to donate upon death), non-donors (do not want to donate), and undecided (uncertain about donation preference)

. 14.7% of participants believed the true definition of brain death to be false

Iriarte Spain 2012 [32]

Show whether there is confusion amongst students about brain death and to investigate whether teaching in medical schools could influence knowledge about brain death held by students

67% of nursing students believed a brain dead patient was in coma and still alive. Percentage of medical students who believed brain dead patient is dead varied with the year of schooling with lowest being 38% in 5th year and highest being 72% in 3rd year of medical school

Joffe et al. Canada 2008 [46]

To determine if university students consider the donation after cardiac death donor as dead

Less than half of the respondents consider the patients in the DCDD scenarios dead (45%) or consider the physicians truthful in describing the patients as definitely dead (52%)

Joffe et al. Canada 2008 [41]

To determine whether paediatricians consider the donation-after-cardiac-death donor as dead

Given scenarios of patients being dead as per current DCDD guidelines, < / = 60% of physicians considered patients as dead. Only 3.8% allowed DCDD despite disagreeing or strongly disagreeing that the patient was definitely dead suggesting general support for Dead Donor Rule

Joffe et al. USA 2012 [22]

To determine whether board-certified neurologists in the United States agree with the standard definition of death and understand the criteria and the empirical state of the brain diagnosed by the tests used to confirm BD

Most neurologists do not understand or disagree that certain brain functions, including EEG activity (70%), evoked potential activity (56%), cerebral blood flow (52%)and hypothalamic neuroendocrine function (9%), often can remain in patients diagnosed dead using accepted tests. This suggests that these neurologists think that clinical tests for BD produce many false-positive diagnoses of death

Keenan et al. Canada 2002 [56]

To determine the attitudes toward organ donation from non–heart-beating cadaver donors in a sample of the general public and health care workers

Both the general public and health care workers support the use of non-heart-beating cadaver donors once a decision has been made to withdraw life support

Kubler et al. Poland 2009 [33]

To evaluate the attitude of university students to the concepts of brain death and organ retrieval, compared with the attitude of critical care physicians

98.6% of physicians know BD is legally dead, however 27.3% would consider brain dead as good as dead. 11.8% of physicians classified correctly severely brain injured person as alive but were willing to donate organs. The corresponding figure for patients in vegetative state was 8%

Lee et al. 2018 [57]

Relationship between attitudes to DCDD and palliative medication prescription among intensive care physicians

38% were concerned that DCD patients would receive inappropriate doses of palliative care medications

Some thought prescribing high doses of palliative medications would be perceived as hastening death

Lewis et al. 2020 [60]

Attitudes of American Muslim HCPs to BD and its relationship with religiosity

84% of Muslim Allied Health Professionals believe that a person declared brain dead according to the American Academy of Neurology guidelines is truly dead

Lomero et al. Spain 2015 [24]

Attitude and knowledge regarding donation and transplantation of the medical and nursing staff at a community hospital in the province of Barcelona

69.1% agreed with the view that brain death is equivalent to death

Marck et al. Australia 2012 [30]

A cross-sectional survey was conducted to assess Australian ED clinicians’ acceptance and knowledge regarding BD

The majority (85.5%, n = 578) of respondents accepted BD, agreeing that “BD is a valid determination of death,” while 11% (n = 73) disagreed, and 4% (n = 25) replied “don’t know.” 37% of those who replied disagreed or don’t know said so due to “doubts on the scientific definition of BD”

Marcum USA 2002 [14]

The purpose of this study was to investigate operating room nurses' knowledge level of the organ transplant retrieval process and their attitudes toward organ donation

20% of operating room nurses disagreed with the definition of brain death

Mathur et al. USA 2008 [42]

Perception, level of knowledge, and understanding of DCDD and the effect of an educational intervention

Good support (82%) for giving medications such as heparin to improve the chances of successful donation after cardiac death. 37% were neutral and 14% disagreed that 5 min of unresponsiveness, apnoea and asystole are sufficient to pronounce death after withdrawing life support therapy

Mikla et al. Poland 2015 [11]

To analyze the knowledge and acceptance of the brain death (BD) concept among nursing students

(n = 369) knew the concept of BD and considered it to mean a person’s death. Of the rest, 19% (n = 93) did not know it, and the remaining 6% (n = 30) believed that it did not mean that a person was dead

Nair-Collins et al. USA 2015 [49]

To evaluate the public’s opinion about organ removal if explicitly described as causing the death of a donor in irreversible apneic coma

19–38% of people willing to donate their organs after death were either unsure or unwilling to donate their organs in the circumstance of irreversible apneic coma with organ removal causing biological death

Nasrollahzadeh et al. Iran 2003 [27]

To examine the critical items that influence nurse knowledge regarding the concept of brain death and attitudes toward cadaveric donor renal Tx

67% understood BD = death, but only 40% understood true concept and importance to BDD

Nowak et al. Poland 2014 [34]

Assessed young people’s knowledge and attitudes towards determining death in transplantology and their impact on attitude toward organ transplantation

85% of medical students and 54% of nonmedical students considered BD as the death of a human being, and the majority of the remaining group was reluctant to form a final opinion about this statement rather than simply deny it

Oo et al. 2020 [61]

Attitudes and knowledge of Malaysian ICU nurses regarding OD and BD, and relationship with sociodemographic attributes

12.1% of Malaysian HCW were not convinced or unsure of the clinical state called brain death

Othman et al. 2020 [38]

International study comparing public opinion to BD vs DCDD

87.9% of participants exposed to the circulatory death vignette were certain that the patient was truly dead vs 84.1% in the group exposed to the brain death case vignette a small but significant difference (Cohen's d 0.176; p = 0:004

Public survey Canada 2005 [37]

To survey the general public on awareness, attitudes and behaviours related to organ and tissue donation including the issue of donation after cardiac death

16% found the fact that surgery can start 5 min after heart stopping as unacceptable, 24 and 30% found the it unacceptable to perform procedures or administer medications to preserve organs respectively

20% believed doctors may prematurely declare a patient dead in order to get a potential organ donation

Rodrigue et al. USA 2018 [48]

To develop a questionnaire to measure health-care providers’ DCDD attitudes that can be quantified and standardized for use in research, quality improvement, and educational contexts

31% felt less comfortable with DCDD as compared to BD organ donation and 16% felt that the time of asystole or pulselessness to declare death in context of DCDD is too short. 11% felt death is declared too soon in DCD

Rodriguez-Arias Spain France USA 2013 [47]

Health professionals’ experience, beliefs and attitudes towards brain death and two types DCDD—controlled and uncontrolled

94% of HP believed patient who is BD is dead. This figure was 84% for uncontrolled DCDD and fell to 57% for a scenario of controlled DCDD. 55–60% of HP thought it was necessary to demonstrate BD in the DCDD scenarios

Roels et al. multiple countries 2010 [20]

Impact of Critical Care staffs’ attitudes to organ donation, their acceptance of the BD concept, their self-reported skills and educational needs on national donation rates

Support for the statement ‘Brain death is a valid determination of death’ was the highest in Norway (94.7%) and Belgium (89.7%) and the lowest in Croatia (67.4%) and Japan (36.4%) (average: 79.4 ± 16.3%). In each country and on average, acceptance of the BD concept was lower amongst nursing staff. Acceptance had a strong correlation with retrieval efficiency index

Rozaidi et al. Malaysia 2000 [28]

1. The concept of brain death

2. Withdrawal and the discontinuation of life support in brain dead patients

3. The acceptance of cadaveric organ donation and transplantation

83.8% accepted BD; 8.5% rejected it, 7.7% unsure. The reasons for not accepting were mostly religious beliefs and the perception of lack of evidence around the concept

Sarnaik et USA 2013 [39]

Views of pediatric intensive care physicians on the ethics of pediatric donation after cardiac death

25% of the participants believe DCDD donors feel pain during the harvest procedure as Anaesthesia is not administered

Schicktanz et al. Germany 2017 [35]

Attitudes towards organ donation, medical and economics students

More than 55% of individuals don’t agree or don’t know if the person is dead after brain stops functioning completely. 28.2% of people surveyed believed the person is dead if the regions of brain controlling personality thinking and speech are irreversibly destroyed

Siminoff et al. USA 2004 [36]

Public attitudes and beliefs about the determination of death and its relationship to organ transplantation

one-third (33.7%) believed that someone who was brain dead was legally dead, 43.3% referred to brain dead patients " as good as dead" while 16.3% considered them alive. 33.5% were willing to donate the organs of patients they classified as alive seemingly in violation of dead donor rule. 57.2% identified the patient in a coma as dead, and 34.1% identified the patient in a PVS as dead

Skwirczyńska et al. 2019 [58]

Attitudes to and knowledge of DCDD compared with BD among intensive care medical staff in Poland

79% of respondents declared acceptance of neurologic criteria as adequate to diagnose death in the case of a potential organ donor, 12% of respondents indicated circulation criteria, and only 9% declared both criteria as suitable for the diagnosis of death. A considerable percentage of respondents (79%) do not accept equivalent consideration of cardiovascular and neurologic criteria as suitable for diagnosing the death of a potential donor

Teixeira et al. Brazil 2012 [12]

Influence of understanding of brain death on organ donation

The majority of the population under study does not understand the meaning of BD and believes that the deceased potential donor might yet live. Trust in the diagnosis was directly correlated with favourable opinion towards organ donation. There was no statistical correlation between the level of education and the lack of understanding of BD

Yang et al. China 2015 [29]

To better understand the factors influencing the Chinese perception of brain death

34.1% found brain death ethically unacceptable. Only 50.7% considered a patient presented in a brain-dead scenario as dead, 51.9% were willing to withdraw

Youngner et al. USA 1989 [21]

Knowledge of, and concepts about, (1) the determination of death among physicians and nurses most likely to become involved in the identification and medical management of potential donors, (2) the discussion of the donation option with families, or (3) the actual retrieval of organs

95% considered loss of all brain function as death. 38% of respondents expressed irreversible loss of cortical function i.e. higher brain death concept as death. Many more with a higher brain concept as compared to lower/or whole brain concept thought that it was morally permissible to retrieve organs from patient who had lost all cortical function (68% vs 11%, P < .001)