Table 3.

Included articles, analyzed in rounds 1 and 2

First round (37 articles, 20%)	Category	Article type	Study characteristics
1 Kolarik 2002 [10]	Contemplative, focus not specified	Conceptual paper	List of objectives for ACP: patient objectives, family or surrogate objectives, health care provider objectives, desirable characteristics of the process.
2 Hackler 2004 [11]	Idem	Ethical paper	Exploration of two kinds of justifications for advance directives, with two case descriptions.
3 Rietjens 2016 [12]	Idem	Editorial	Editorial for special issue about ACP.
4 Aitken 1999 [13]	Idem	Overview	Overview article about ACP for family physicians.
5 Hammes 2001 [14]	Idem	Editorial	Editorial.
6 Perkins 2007 [15]	Idem	Perspective	Perspective on the role of advance directives.
7 Schicktanz 2009 [16]	Idem	Ethical paper	Ethical considerations of the interplay between personal and cultural identity in interpreting advance directives.
8 Sudore 2010 [17]	Idem	Perspective	Perspective on the objective of ACP.
9 Robins-Browne 2014 [18]	Idem	Ethical paper	Ethical considerations about the complexities of ACP.
10 Johnson 2017 [19]	Idem	Ethical paper	Ethical considerations about the role of ACP in end-of-life care.
11 Van Delden 2017 [20]	Idem	Commentary	Commentary on the PREPARE-trial.
12 Vogel 2011 [21]	Idem	News item	News about the Canadian framework for ACP.
13 Wheatley 2015 [22]	Idem	Ethical paper	Ethical issues in palliative care, including ACP.
14 Song 2016 [23]	Empirical, culture-focused	RCT	ACP intervention ‘SPIRIT’ vs. usual care. Subjects: 210 dyads of patients on dialysis and their surrogates; subgroup analysis of African Americans vs. whites. Outcome measures: dyad congruence on goals of care, surrogate decision-making confidence, patient decisional conflict, surrogate anxiety, surrogate depression, surrogate post-traumatic distress symptoms.
15 Asai 1997 [24]	Idem	Focus group	Focus group on life-sustaining treatments for terminally ill patients and attitudes towards advance directives and possible barriers to using them in the clinical setting. Subjects: 7 specialists in internal medicine from Japan.
16 Perkins 2002 [25]	Idem	Interview study	Interviews about cultural attitudes influcancing decisions whether to perform ACP. Subjects: a purposive sample of 26 Mexican-American, 18 Euro-American, and 14 African-American inpatients in Texas, USA.
17 Ko 2012 [26]	Idem	Focus groups	Focus group and interview study to explore knowledge, attitudes, and behavior about advance directives in Korean Americans. Subjects: 23 Korean Americans.
18 Wicher 2012 [27]	Review, culture-focused	Systematic review	Systematic review of 46 studies examining African American preferences related to end-of-life care and decision making.
19 Singer 1998 [28]	Empirical, focus not specified	Interview study	Interviews about the purpose of ACP. Subjects: 48 patients on hemodialysis.
20 Robinson 2011 [29]	Idem	Interview study	Interviews about the applicability and usefulness of an ACP intervention and the ACP process. Subjects: 9 dyads of patients with advanced lung cancer and a family member, who participated in an ACP intervention.
21 Jeong 2012 [30]	Idem	Interview study	Interviews based on the ‘Values Clarification Worksheet’. Subjects: 3 residents living in an residential aged care facility in Australia, 11 family members, and 13 registered nurses.
22 Sudore 2017 [31]	Idem	Delphi study	Delphi study on the definition of ACP.
23 Rhee 2013 [32]	Idem	Interview study	Interviews on the impact of ACP on interpersonal relationships. Subjects: 17 general practitioners in Australia.
24 Michael 2017 [33]	Idem	Focus groups	Focus groups exploring awareness, attitudes, and experiences of ACP. Subjects: 15 community dwelling older people and 27 unrelated offspring/caregivers of older people.
25 Martin 1999 [34]	Empirical, disease-focused	Interview study	Interviews about experiences with and opinions about ACP. Subjects: 140 patients with HIV/AIDS who had participated in an ACP trial.
26 Johnson 2017 [35]	Idem	Interview study	Interviews about patient autonomy and ACP. Subjects: 11 consultant oncologists and 7 palliative medicine doctors.
27 Loggers 2014 [36]	Idem	Mixed methods study with survey (quantitative) and interview (qualitative) part	Survey and interview about experiences with ACP. Subjects: 18 patients after hematopoietic cell transplants and 11 bereaved caregivers of patients who had died after hematopoietic cell transplant. Outcome measures (quantitative): having a living will; having a formally designated proxy; having discussed some aspect of ACP with family/friend prior to transplant; perceptions of the value of ACP; having discussed mortality risk with the medical team pre transplantation; hope; medical team’s commitment.
28 Thoresen 2016 [37]	Idem	Participant observation and interviews	Participant observation of ACP conversations, followed by interviews. Subjects: 7 nursing home patients in 7 different nursing homes in Norway and the relatives who joined the ACP conversation.
29 Sellars 2017 [38]	Idem	Interview study	Interviews about patient and caregiver perspectives on ACP. Subjects: 24 patients with end stage renal disease and their caregivers (n = 15).
30 Johnson 2016 [39]	Review, disease-focused	Systematic review with thematic analysis	Systematic review of perceptions and experiences on ACP of cancer patients, their families, and health care providers. Thematic analysis was performed on the included studies: 19 quantitative studies, 17 qualitative studies, 4 mixed methods studies.
31 Mehlis 2016 [40]	Review, focus not specified	Ethical and legal perspective	Ethical and legal perspective on self-determination and the risk of overtreatment, with a focus on ACP.
32 Llewellyn 2017 [41]	Idem	Interview study	Interviews about death and dying and reflections on the effect of these conversations. Subjects: 21 healthy adults 54–65 years old.
33 Sanchez-Gonzalez 1997 [42]	Contemplative, culture-focused	Medical history perspective	Historical perspective on the emergence of advance directives in the USA, as compared to Europe. Focus on cultural differences.
34 Schmidt 2017 [43]	Contemplative, disease-focused	Overview	Overview article about incorporating ACP on hemodialysis units.
35 Holley 2005 [44]	Idem	Perspective	Perspective on the timing, purpose, and effect of ACP in patients with end-stage renal disease.
36 Gastmans 2010 [45]	Idem	Ethical perspective	Ethical perspective on euthanasia and advance euthanasia directives for patients with severe dementia.
37 Holley 2012 [46]	Idem	Overview	Overview article on the role and timing of ACP for patients with chronic kidney disease and end-stage renal disease.
Second round (18 articles, 10%)	Category	Article type	Study characteristics
38 Schwartz 2002 [47]	Empirical, focus not specified	Randomized controlled trial (pilot study)	Pilot randomized controlled trial of an ACP intervention. Subjects: 61 ambulatory geriatric patients. Intervention: ACP discussion with a trained nurse facilitator and documentation of patient goals and preferences. Control: Massachusetts Health Care Proxy form. Outcome measures: knowledge of ACP; treatment preferences (and congruence between patient and health care agents; response shifts in values; quality of life.
39 Seymour 2004 [48]	Idem	Focus groups	Focus groups on advance care statements. Subjects: 32 older people or their representatives.
40 Cornally 2015 [49]	Idem	Focus groups	Focus groups on the implementation of the ‘Let me decide’ ACP program. Subjects: 15 clinical nurse managers and 2 directors of nursing in long term care facilities where the ‘Let me decide’ ACP program had been implemented.
41 Stanford 2013 [50]	Empirical, culture-focused	Focus groups	Focus group study on the perceived relevance of ACP in Knysna, South Africa. Subjects: 51 participants including pastors, hospice staff, teachers, and community caregivers in Knysna, South Africa.
42 Lee 2016 [51]	Idem	Interview study	Interview study on signing one’s own do-not-resuscitate directive among older nursing home residents in Taiwan. Subjects: 11 older nursing home residents from Taiwan.
43 Zientek 2006 [52]	Contemplative, culture-focused	Ethical perspective	Ethical considerations regarding end-of-life care and the role of advance directives in Texas, and their impact on Roman Catholic health care providers.
44 Prendergast 2001 [53]	Contemplative, disease-focused	Overview, historical perspective	Historical overview of the development of ACP in the first decade since the Patient Self-Determination Act, with a focus on its importance for intensive care units.
45 Kuhlmann 2016 [54]	Idem	Overview, historical perspective	Overview of the development and importance of ACP for patients with end-stage renal disease.
46 Drought 2002 [55]	Review, focus not specified	Review and ethnographic study	Literature review on the role of choice in end-of-life decision making, followed by an ethnographic study. Subjects: 88 terminally ill patients with solid tumor cancer or AIDS who were followed longitudinally, together with 1–3 of their family members or friends, and 2 of their outpatient clinic providers.
47 Robertson 1991 [56]	Contemplative, focus not specified	Opinion	Opinion article on the role of advance directives.
48 Levinsky 1996 [57]	Idem	Opinion	Opinion article on the purpose of advance medical planning.
49 Darr 1996 [58]	Idem	Overview	Overview article on the use of advance directives.
50 Davis 2002 [59]	Idem	Ethical perspective	Ethical perspective on the concept of precedent autonomy in advance directives.
51 Edwards 2011 [60]	Idem	Ethical perspective	Ethical perspective on the concept of precedent autonomy and the theory of ‘the other self’ in relation to advance directives.
52 Ahluwalia 2012 [61]	Idem	Letter to the editor	Comment stating that an earlier article wrongfully used a too narrow definition of ACP.
53 Wolff 2012 [62]	Idem	Ethical perspective	Ethical perspective on the role of autonomy, quality of life, and advance directives in end-of-life decision making for patients with dementia.
54 Davison 2006 [63]	Empirical, disease-focused	Interview study	Interviews on the role of hope in the context of ACP. Subjects: 19 patients with end-stage renal disease.
55 Piers 2013 [64]	Idem	Interview study	Interviews on the views of older people on ACP. Subjects: 38 older people (71–104 years old) with limited prognosis due to malignancy, organ failure, or frailty.