The development of a core outcome set for evaluating and enhancing palliative sedation in clinical research and practice: The COSEDATION study protocol

Abstract

Background:

The practice of palliative sedation (PS) in end-of-life care has generated significant debate due to concerns about improper application and communication issues. Previous efforts to assess and enhance the practice have often focused on single outcomes, resulting in incomplete evaluations. There is currently no consensus on the core outcomes needed to assess PS effectively.

Aim:

This study aims to develop a core outcome set (COS) for PS in end-of-life care to enable comprehensive evaluation and improve clinical practice.

Design:

The study follows the four-stage Core Outcome Measures in Effectiveness Trials (COMET) initiative approach to develop the set of core outcomes.

Methods and analysis:

First, we will conduct a scoping review to identify potentially relevant outcomes reported in existing peer-reviewed and gray literature. Second, we will employ qualitative methods to explore outcomes valued by patients, their proxies, and healthcare professionals. Third, experts, including researchers, healthcare providers and bereaved relatives, and patient advocates will assess the importance of these outcomes through a Delphi study. Finally, a consensus meeting with stakeholder representatives will refine the COS. Concurrently, measurement instruments for these core outcomes will be identified.

Ethics:

Ethical clearance was obtained by the Ghent University Hospital Ethics Committee for the whole study (ONZ-2023-0050).

Discussion:

This study is crucial for establishing a gold-standard measurement instrument to evaluate the multifaceted practice of PS in all its complexity. Providing a standardized set of outcomes will facilitate the design and evaluation of clinical trials, support effective quality improvement initiatives, and inform evidence-based decision-making in healthcare. Engaging all key stakeholders, including dying persons and their families, significantly improving patient care. Furthermore, internationally validated, clinically relevant endpoints will further strengthen research impact and promote consistent, high-quality PS practices worldwide.

Plain language summary

Developing a standard set of outcomes to improve palliative sedation in end-of-life care

Palliative sedation is a treatment that can help people at the end of their lives by reducing severe pain and distress. It gently lowers their level of awareness to bring comfort when other treatments no longer work. While this can be a vital part of end-of-life care, there is still confusion about how it is used and which key elements are essential to determining the overall quality of palliative sedation practice. At the moment, there is no clear agreement on which outcomes—such as comfort, communication, or family support—are most important to measure. Without this agreement, it is hard to improve care and make sure patients and families get the support they need. Our study aims to solve this by creating a standard list of the most important outcomes for palliative sedation. We will do this by first looking at past research to see what has already been measured. We will also talk to patients, families, and healthcare professionals to understand what they think truly matters. Then, a group of experts—like doctors, nurses, and family members—will help decide which outcomes are the most important. Finally, we will bring everyone together to agree on one clear list. This list will help doctors, nurses, and researchers focus on what really matters when providing palliative sedation. It will make care more consistent, compassionate, and patient-centered. Most importantly, it will ensure that the voices of patients and families are heard, so their needs are met during one of life’s most difficult moments. With this work, we hope to improve end-of-life care for people around the world and bring comfort when it is needed most.

Keywords

palliative sedation continuous deep sedation end-of-life core outcome set quality improvement Delphi study

Introduction

Some individuals who are nearing the end of their lives may experience severe symptoms such as intractable pain, dyspnea, and delirium that cannot be relieved despite extensive medical and palliative care.¹ In such situations, healthcare professionals, individuals who are dying, and their loved ones may consider palliative sedation (PS) as a last-resort treatment. PS involves administering sedative drugs to induce a state of decreased or absent awareness of a person’s experience of suffering.² Research suggests that PS is commonly used across all care settings where people die and is estimated to involve between 2.5% and 18.2% of all deaths in Europe and 10% of deaths in the United States.^3
–7

Though increasingly prevalent internationally, controversial issues about almost every aspect of the practice persist.^8,9 First, there are still large variations in the terms and definitions currently used, and these terms and definitions often reflect one’s normative position on sedation at the end of life.^10,11 For instance, definitions may include value-laden elements, such as intentions, indications, and patient selection, which can limit the scope of the practice and preempt an ethical debate.¹⁰ Second, palliative sedation is said to have potentially life-shortening effects, and some shared similarities with medical acts intended to shorten or end a patient’s life deliberately, in what has been described as ‘slow euthanasia’.¹⁰ Also it often takes away the patient’s ability to communicate, which can be perceived as imposing a form of social death on the patient.^10,12,13 Lastly, controversy extends into clinical practice, with discussions being raised about the conditions under which it should be performed and how it should be performed.¹⁴ Empirical studies have described heterogeneous practices involving sedatives for terminally ill patients in different countries and subpopulations.¹⁵ Palliative sedation is sometimes performed suboptimally, and clinicians are not well acquainted with generally recommended indications, leading to uncertainty about whether, when, and how to start.^4,16,17 Moreover, dying persons and relatives are often inadequately involved in the decision-making and ill-informed about what to expect during sedation, leading to a perceived poor quality of dying and issues with coping.^18,19 All these issues highlight the need for comprehensive and ongoing monitoring of PS practices, and targeted initiatives to enhance them in all relevant areas.²⁰ Given its growing application in clinical settings, it is essential to ensure that PS continues to contribute to optimal care by making the dying person comfortable. By addressing these concerns and continuously evaluating the practice, PS can maintain its role in delivering effective and optimal end-of-life care.²¹

Previous initiatives to evaluate and improve the practice have mostly been limited to simple descriptive reports or focused narrowly on single outcome domains, such as the level of consciousness, and are unlikely to reflect the overall quality of the practice.^2,22 For instance, PS should be used proportionally to the severity of the dying person’s symptoms; however, not all relatives may be informed of the decision or allowed to say goodbye. Merely focusing on one aspect of the practice may ignore relevant aspects in other domains, leading to an incomplete evaluation of the overall quality of palliative sedation.^2,20,23 Establishing a gold standard that accurately reflects the overall quality of the practice is essential for effectively monitoring and improving the practice.^20,23 This standard will facilitate meaningful evaluations and comparisons across various clinical improvement studies, enabling the identification of the most effective initiatives. By fostering a shared understanding of palliative sedation, consistency in decision-making can be assured across healthcare providers and settings, and will ultimately facilitate more evidence-based, aligned, and effective care decisions.

By fostering a shared understanding of palliative sedation, consistency in decision-making can be ensured across healthcare providers and settings. This approach ultimately facilitates more evidence-based, aligned, and effective care decisions.

Therefore, the COSEDATION project aims to identify and propose a set of core outcomes (e.g. a standardized set of outcomes that should be measured and reported, at a minimum, in specific healthcare areas²⁴) for the use and evaluation of palliative sedation in end-of-life care. The core outcome set (COS) is intended for research and clinical practice, as it will optimize decision-making in clinical practice and improve the comparability of interventional studies. The COS is expected to be relevant in all settings where an individual may be cared for at the end of life: at home, in the hospital, in hospices, or other facilities.²⁵

Materials and methods

Study design

This study follows the COMET (Core Outcome Measures in Effectiveness Trials) initiative approach²⁶ and adheres to the COS-STAD recommendations and checklist for COS development.²⁴ The development of COS involves four stages (see Figure 1)²⁷:

(1) Identifying existing knowledge: A scoping review will be conducted to identify relevant clinical and process outcomes for the quality of palliative sedation, drawing from peer-reviewed and gray literature.

(2) Filling knowledge gaps: We will use qualitative methods to identify and define care outcomes at the end of life, as determined by patients and their proxies.

(3) Prioritizing outcomes: An anonymous, web-based Delphi questionnaire will be used to prioritize outcomes identified in the first two stages, involving former relatives or patients, healthcare professionals specialized in PS, other healthcare professionals, and national academics and researchers.

(4) Consensus meeting: A Delphi consensus meeting with experts from each stakeholder group will be held to define, endorse, and propose the final COS. During this stage, measurement instruments for each core outcome will be identified or developed. A consensus process will be used to finalize the recommended outcome measurement instruments if possible.

Through this process, we will define the most important outcomes of palliative sedation. After the four stages of the COSedation project, the COS will be field-tested in all relevant care (inpatient and home) settings across Flanders, Belgium. While this protocol focuses on the development of the COS, the validation phase will be a crucial next step, refined in collaboration with stakeholders and depending on the final tool. The current focus on the Flemish context is a deliberate choice, given its specific healthcare structure and sociocultural setting. We acknowledge that outcomes may be shaped by these contextual factors, and thus the applicability of the COS outside Flanders cannot be assumed without risk of sociocultural bias. Therefore, any international validation will not be a simple replication, but will be informed by the insights gained and methodological refinements identified through this study. We intend to conduct a brief international validation study to assess applicability in other settings and contexts, while recognizing that broader implementation will likely require a more extensive, context-sensitive process. This study is registered on the COMET database (https://www.comet-initiative.org/Studies/Details/3161). Where applicable, recommendations for interventional trials (Standard Protocol Items Recommendations for Interventional Trails) guidelines were followed when constructing the protocol for this study (Supplemental Material).

Figure 1.

Four-staged approach to develop the COS for palliative sedation + validation (not included in this study protocol).

Stages and methods

Stage 1: Identifying existing knowledge

The scoping review, which aims to identify existing quality indicators and outcomes, will summarize which outcomes are measured, the instruments used, the timing of assessments, and who reports on these outcomes (whether the dying person, the family, or a healthcare provider). Outcomes will then be categorized into several potential domains relevant to assessing the quality of palliative sedation at the end of life. The design of this scoping review is based on the six-stage methodological framework developed by Arksey and O’Malley²⁸ and refined by Levac et al.²⁹ The Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist will be used to guide the conduct and reporting of this review.³⁰

Definitions

Taking into account the lack of a standard definition or term for palliative sedation,¹⁰ we will include all literature focusing on ‘the use of sedative drugs to induce a state of decreased consciousness until death’.^1,2,10 As previous literature tended to focus only on subdomains or subelements of palliative sedation quality, the aim in this stage will be to search as broadly as possible. Outcomes are defined as in-text references in the results and discussion sections of articles that refer to quality or quality improvements of PS (e.g. this will include not only those strictly labelled as ‘outcomes’ or ‘endpoints’ but also areas of interest identified in observational studies, such as ‘satisfaction with palliative sedation’, and quality-indicating words such as ‘must’, ‘should, ‘essential’, ‘the need for’, ‘favorable/unfavorable’). These quality indicators and potential outcomes will form a comprehensive list for the Delphi Study (Stage 3).

Search strategy

The scoping review will include both peer-reviewed and gray literature, searching databases such as MEDLINE (PubMed), EMBASE, CENTRAL, CINAHL and APA PsycInfo for articles about PS published since 2009 (publication of the European Association for Palliative Care (EAPC) recommended framework for the use of palliative sedation).¹ Gray literature, including Open Access Theses and Mednar, will also be searched. Studies will be included if they focus on palliative sedation and its quality aspects in human populations, with publications in English, while Dutch-language sources are also eligible for gray literature. Literature reviews will be excluded, as well as studies on intermittent or acute sedation in emergency settings. References from included studies will be reviewed for eligibility.

Selection process

All identified records will be imported into the software Rayyan.ai.³¹ Two review team members will independently screen titles and abstracts against inclusion and exclusion criteria. Disagreements at any stage will be resolved through discussion, with a third researcher available for arbitration if needed. During the initial screening, duplicates will be removed, and studies will be categorized as (a) to be included, (b) to be discarded, or (c) unsure. Full-texts of potentially relevant articles (categorized as ‘to be included’ or ‘unsure’) will be obtained and assessed against the inclusion criteria. Articles excluded after full-text review will be categorized based on the reason for exclusion, following the same structured approach as in the initial screening.

Data extraction process

We will extract information for each included study using a data extraction tool. This will include the country, publication date, language, setting, research subjects, study objective, general research design, type of publication, and definition of palliative sedation. Additionally, we will extract data on the concept and results, specifically the definition of sedation and terms used for quality indicators and outcomes will be extracted, the formulation of these outcomes, who is responsible for the assessment (if indicated), whether the indicator is an empirical finding or suggested improvement, and any measurement instruments used (validated or not). The extraction tool will be piloted and refined with an initial set of articles. Any variations or contradictions in outcomes across sources will be noted, as they may indicate that factors such as healthcare systems, cultures, or settings may influence views on what constitutes quality palliative sedation, suggesting that an ideal-typical practice of palliative sedation may vary by context. Therefore, while aiming for a universal set of core outcomes, we may need a contextualized intermediate step to achieve uniformity across settings.

Strategy for data synthesis and selection of outcomes for the Delphi study (stage 3)

The review’s findings will be synthesized narratively. Overlapping outcomes will be grouped and reframed into clear, unique outcomes. These unique outcomes are then inductively coded into themes and further categorized into broader domains using NVivo.³² Recognizing the underrepresentation of patient and relative-reported outcomes in previous research and the impact on perceived quality of dying and coping issues,^18,19 it will be crucial to supplement the current scientific knowledge with these perspectives. This will ensure a comprehensive and inclusive understanding of palliative sedation quality outcomes.

Stage 2: A qualitative interview study with healthcare professionals and bereaved relatives to fill gaps in existing knowledge

It is crucial to identify which key stakeholder groups’ views are not adequately represented in the literature review.²⁷ Previous research tends to underrepresent patient/relatives-reported outcomes.³³ It shows that patients and relatives are not always involved in the medical decision-making, potentially leading to a perceived poor quality of dying and issues with coping.^18,19 Therefore, supplementing the current scientific knowledge and the scoping review with their perspective is essential.

This study will use a qualitative design with a phenomenological approach. This stage of the COS development process aims to deepen the understanding of the needs of patients and families during palliative sedation and to explore whether the priorities of relatives differ from current outcomes used to assess the quality of palliative sedation. It will help identify a list of outcomes significant to individuals with experience in palliative sedation. It will consist of semi-structured interviews with bereaved relatives to identify meaningful outcomes for dying persons and their loved ones. These interviews will begin with open-ended questions aimed at uncovering essential outcomes. The goal of these interviews is to delineate what constitutes a positive or negative experience with palliative sedation from the perspective of bereaved relatives and to determine which outcomes should be included in a COS to reflect the overall quality of palliative sedation comprehensively. These identified outcomes will subsequently be included in the list of outcomes for the Delphi study.

Participants and data collection

The study population will involve a maximum of 30 bereaved relatives. Participants will be selected using a sampling matrix that differentiates between hospital, nursing home, and home settings. Bereaved relatives are defined as individuals who have lost a family member or someone close to them. Eligibility criteria include having experienced the loss of a family member within the past 3 years, having palliative sedation used at the end of life of their loved one, being 18 years or older, and being proficient in the Dutch language. All participants will be required to provide informed consent, with an understanding that consent is voluntary and can be withdrawn at any time during the study.

Depending on participant preference, interviews will be conducted online via video conference software or face to face. Participants will be asked about their perceptions and experiences with palliative sedation at the end of life, focusing on key elements they consider important for the quality of palliative sedation.

Data analysis

To ensure participant confidentiality, personal identifying information (e.g. names) will be removed from the transcripts. However, a brief questionnaire will collect some demographic details (e.g. the setting of the patient’s death) necessary for data analysis. Data analysis will utilize pseudonymized data to protect participant identities. Data will be analyzed using a thematic analysis approach, while also creating one or more causal loop diagram to understand the complexity of the practice and the intertwined nature of quality outcomes.

Given the anticipated diversity within the sample (including variations in time to death, patient age, gender, diagnosis, spiritual beliefs, place of death, education level and relationship to the patient), the analysis will consider these potential subgroups to determine if differing perceptions of quality exist among these groups.

Stage 3: An online Delphi questionnaire with stakeholders to elicit views about the importance of outcomes in consensus process

Having identified a list of potential outcomes in stages 1 and 2, the next step will be assessing the level of importance assigned to each outcome. Conducting a Delphi study is advantageous for achieving consensus among diverse participants.²⁷ A Delphi study ensures anonymity, mitigating the influence of dominant individuals, and allows for the inclusion of a large number of stakeholders. In the COS context, the Delphi technique involves seeking consensus from experts across sequential questionnaires or rounds regarding the importance of various outcomes. Participants’ responses for each outcome are aggregated and anonymously shared in subsequent rounds. Notably, participants can reconsider their initial ratings based on collective feedback from previous rounds, facilitating the convergence of diverse stakeholder perspectives. As emphasized by COMET: this iterative process is crucial for achieving consensus.²⁷ To this end, a three-round Delphi study is proposed.

Participants

The Delphi study will engage four distinct stakeholder groups: healthcare professionals (both specialized and other healthcare professionals), former relatives, patient (advocates), and national research experts. The study aims to recruit a minimum of 30 participants from each group, which will give a total panel of at least 120 participants. Eligibility criteria for all participants include proficiency in Dutch or English and (in)direct experience or expertise in palliative sedation.

Former relatives are individuals who were close to a person undergoing sedation at the end of life, having experienced loss up to 3 years prior to the start of the Delphi Study. Healthcare professionals specialized in palliative sedation will include Belgian palliative care physicians and nurses with specific expertise in the field, irrespective of their work setting. Other healthcare professionals encompass general practitioners, nurses, geriatricians, oncologists, and intensive care physicians with practical knowledge of palliative sedation. The third stakeholder group comprises national academics and researchers engaging in the topic of palliative sedation. A challenge in COS studies is maintaining a patient-centric perspective throughout the Delphi process and consensus meetings, mainly when active patient participation is not feasible, given their end-of-life stage and requisite familiarity with palliative sedation. Accordingly, the study proposes two methods to include the patient perspective: (1) involving individuals nearing the end of life who have engaged in discussions with clinicians regarding palliative sedation, and (2) including bereaved relatives who are identified as prospective candidates for future palliative sedation, complying to the idea of ‘experts by lived experience’. This approach aligns with COMET guidelines, advocating for consultation with an advisory group representing key stakeholders when direct patient involvement is impractical due to resource, practical and ethical constraints.²⁷

With the overarching goal of establishing a universally applicable COS and ensuring high-quality palliative sedation for all stakeholders, the panel will comprise a diverse, heterogeneous group of participants encompassing multiple stakeholder perspectives.

Delphi online rounds

The Delphi online, anonymous study will involve at least two and if needed three rounds, with the exact number contingent upon achieving consensus according to prespecified criteria (see Figure 2). A roster of participants agreeing to participate in the Delphi study will be compiled, with participation entirely voluntary and participants can withdraw at any stage. Several weeks after participant recruitment and upon reaching adequate numbers for each stakeholder category (at least n = 20), Round 1 will start using an online survey platform. To mitigate potential response bias, the order of outcomes will be randomized for each participant.³⁴

Figure 2.

Delphi online study flow chart.

Delphi online survey instrument

The survey will incorporate outcomes identified from the scoping review and interview study. These outcomes will be cognitively tested and pilot-tested for clarity and understandability, incorporating verbatim terms used by relatives in interviews to ensure accessibility across all stakeholder groups. ‘Think aloud’ interviews will be conducted to gauge participant understanding of each item.

Each Delphi round will last approximately 4 weeks. Panel members will rank outcomes in each round. During Round 1, participants can suggest additional outcomes they deem significant but were not previously identified, recognizing that academic literature may not adequately encompass all stakeholder perspectives or current concerns. New outcomes suggested by two or more participants will proceed to Round 2. Participants can also provide feedback on item formulations they find unclear or disagree with.

Participants will score each outcome using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) scale, ranging from 1 to 9 (1–3: not important for inclusion; 4–6: important but not critical; 7–9: critical to include).³⁵ Following each round, outcomes achieving consensus scores indicating limited importance (1–3) will not progress to subsequent rounds. In subsequent rounds, participants will receive median and range scores per outcome by stakeholder group and will re-evaluate their scores accordingly. Participants can provide rationales for their scores, which will be summarized in feedback reports.

In the final round, participants will determine whether each outcome should be included in the COS. Consensus criteria will be applied as follows:

Consensus IN (classify as a core outcome): Over 70% of participants in each group score the outcome ‘critically important’ (scores 7–9), and less than 15% in each group score it as ‘limited importance’ (scores 1–3)

Consensus OUT (do not classify as a core outcome): Over 70% of panel members in each group score the outcome ‘of limited importance’ (scores 1–3) and less than 15% in each group score the outcome ‘critically important’ (scores 7–9)

No consensus (do not classify as a core outcome): For all other outcomes.

Demographic information will be collected in round one, including date of birth, gender, educational qualification, type of experience with palliative sedation, and setting of experience (home setting, hospital curable service, hospital palliative unit, and nursing home). Round two will provide participants with feedback on score distributions and average scores per outcome across stakeholder groups, for re-evaluation. Outcomes deemed nonconsensus in Round 1 for ‘not important for inclusion’ will be excluded. Round three will enable participants to rate any new suggested outcomes that did not achieve consensus in round two.

Stage 4: Delphi consensus meeting with stakeholders to finalize the recommended COS and select outcome measurement tools

The final stage of a Delphi will involve a face-to-face or web-based consensus meeting (to be determined). The main objective of these meetings is not to revise the content of the COS but to define, endorse, and propose the final COS. This includes refining the wording, operationalization, and implementation strategies. Participants will be purposefully sampled from those involved in the Delphi study, ensuring diverse representation from the broader stakeholder group, including different healthcare settings. At least one consensus meeting will be conducted with participation from at least 20% of the Delphi study participants to ratify findings and address any uncertainty that may require additional voting. No new outcomes will be considered at this stage. Given the potential for hierarchy imbalance, with experienced healthcare providers alongside nurses and relatively inexperienced family members, the meeting will be facilitated by an expert. However, to mitigate any undue influence or peer pressure affecting consensus voting, multiple consensus meetings may be considered with different stakeholder groups. Organizing a single consensus meeting involving all stakeholders is preferred, as it ensures comprehensive stakeholder engagement and facilitates genuine consensus.³⁶ This approach allows for thorough discussions on feasibility and differing priorities among stakeholders. During this final stage, if needed, participants can also evaluate measurement instruments for each core outcome. We have gathered all relevant measurement instruments linked to each core outcome during the scoping review, which provides a comprehensive overview and identifies validated and consensus-based measurement tools for some outcome. For outcomes without previously established consensus, a list of recommended instruments will be compiled based on participant feedback and consensus, considering both scientific evidence and practical feasibility.

Data management

All data collected that could lead to identification of the involved persons will be pseudonymized in external communications, including publications. Where possible, the researcher will request participant consent prior to collecting qualitative data. All collected data will be securely stored on an encrypted server of Ghent University, which is only accessible to members of the research team. All paper surveys are stored in a locked cabinet. In accordance with the Good Clinical Practice guidelines, the electronic (raw) data (privacy-sensitive information or any other information that could lead to the identification of individual people) will be stored for 15 years. Audio files will be deleted as soon as they have been transcribed.

Discussion

This study protocol outlines the method for developing a COS to assess and improve the practice of palliative sedation in clinical research and practice, aligning with recommendations from the COMET initiative.²⁷

The absence of a COS for best practices in palliative sedation has led to various outcomes being used in clinical studies, resulting in many interpretations and conclusions. This project could have a key scientific impact as it will identify what minimum outcomes should be used to determine the efficacy and quality of this end-of-life practice. Developing, operationalizing, and validating a COS will reduce heterogeneity between studies, making it easier for results to be compared, contrasted, and combined as appropriate. Importantly, it would enhance the value of evidence synthesis by reducing the risk of outcome-reporting bias and ensuring that all clinical studies contribute usable information. This COS also applies to observational studies using routine health records and can be utilized by those designing data collection tools within healthcare services. This should eventually promote consistency in data collection across healthcare providers, enabling clinical audits and secondary analysis.

Developing COSs is also a healthcare priority and will ultimately translate into the best care for dying people and their families. By recognizing the expertise and crucial contribution of each key stakeholder, including dying persons and their loved ones, the insights from this study will be crucial for clinical practice to make more informed health decisions, considering each stakeholder group’s priorities. A key strength of this project is the explicit inclusion of patient- and relative-reported outcomes, which have been underrepresented in previous research, despite their significant impact on perceived quality of dying and coping. Addressing this gap will ensure a more comprehensive and inclusive understanding of palliative sedation quality outcomes, strengthening the relevance of the final COS for clinical practice. The COS is expected to become a standard of palliative sedation quality and care provided to patients in the last days of life. The selection of a gold standard will facilitate our understanding of which quality improvement initiatives are worth implementing in real-world applications, practice, and policy.

The final COS will be shared with all stakeholders. Patients and public representatives will be encouraged and supported to share the difference they have made. A collaborative dissemination plan will be formulated in consultation with all stakeholders. This plan will include submitting the findings for publication in a peer-reviewed journal and promoting the adoption of the COS through various channels, ensuring wide accessibility and implementation. This project also aims at completing a field-testing study after the final COS is established. While initially developed within a Flemish context, we also aim to explore its broader applicability in international settings and assess how it can be effectively translated into wider practice.

Conclusion

This study protocol outlines the development of a COS for evaluating and enhancing palliative sedation at the end of life, intended for both scientific research and clinical practice. Establishing a standardized set of outcomes is essential to capture the complexity of this multifaceted practice. It will enable the design and evaluation of clinical trials, guide quality improvement initiatives, and support evidence-based decision-making in palliative care. By actively involving key stakeholders – including patients nearing the end of life and their families – the study aims to ensure that the outcomes are meaningful and relevant to those most affected. Developing internationally validated and clinically applicable endpoints will ultimately strengthen research quality and promote consistent, high-quality palliative sedation practices worldwide.

Supplemental Material

sj-docx-1-pcr-10.1177_26323524251340706 – Supplemental material for The development of a core outcome set for evaluating and enhancing palliative sedation in clinical research and practice: The COSEDATION study protocol

Supplemental material, sj-docx-1-pcr-10.1177_26323524251340706 for The development of a core outcome set for evaluating and enhancing palliative sedation in clinical research and practice: The COSEDATION study protocol by Lenzo Robijn, Indra Albrecht, Joni Gilissen, Peter Pype, Jeroen Hasselaar, Luc Deliens and Kenneth Chambaere in Palliative Care and Social Practice

Supplemental Material

sj-docx-2-pcr-10.1177_26323524251340706 – Supplemental material for The development of a core outcome set for evaluating and enhancing palliative sedation in clinical research and practice: The COSEDATION study protocol

Supplemental material, sj-docx-2-pcr-10.1177_26323524251340706 for The development of a core outcome set for evaluating and enhancing palliative sedation in clinical research and practice: The COSEDATION study protocol by Lenzo Robijn, Indra Albrecht, Joni Gilissen, Peter Pype, Jeroen Hasselaar, Luc Deliens and Kenneth Chambaere in Palliative Care and Social Practice

Footnotes

Acknowledgements

The authors thank their loved ones for their support in developing this project.

Authors’ Note

Lenzo Robijn is also affiliated to End-of-Life Care Research Group, Ghent University, Belgium and Center for Interprofessional Collaboration in Education, Research and Practice, Ghent University, Belgium

ORCID iDs

Lenzo Robijn

Luc Deliens

Kenneth Chambaere

Ethical considerations

Ethical clearance was obtained by the Ghent University Hospital Ethics Committee for the whole study, including the interview study, the Delphi Study, and the consensus meeting (ONZ-2023-0050).

Consent to participate

All participants will provide voluntary informed written consent before taking part in this study. All methods will be performed in accordance with the Declaration of Helsinki.

Author contributions

Lenzo Robijn: Conceptualization; Funding acquisition; Investigation; Methodology; Project administration; Supervision; Writing – original draft; Writing – review & editing.

Indra Albrecht: Conceptualization; Methodology; Writing – original draft; Writing – review & editing.

Joni Gilissen: Conceptualization; Writing – review & editing.

Peter Pype: Conceptualization; Funding acquisition; Methodology; Project administration; Writing – review & editing.

Jeroen Hasselaar: Funding acquisition; Writing – review & editing.

Luc Deliens: Conceptualization; Funding acquisition; Methodology; Writing – review & editing.

Kenneth Chambaere: Conceptualization; Funding acquisition; Methodology; Project administration; Supervision; Writing – review & editing.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study is funded by Research Foundation Flanders (FWO) under grant agreement G0A9622N. The funding source had no role in the study design, or in the drafting of this article.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data availability statement

This study protocol does not contain any generated data that can be shared with or made available to third parties.

Supplemental material

Supplemental material for this article is available online.

Trial registration

This study has been registered with the COMET Initiative as study 3161 () and will follow its recommended methodological procedures.

References

Surges

Brunsch

Jaspers

, et al. Revised European Association for Palliative Care (EAPC) recommended framework on palliative sedation: an international Delphi study. Palliat Med 2024; 38: 213–228.

Robijn

Deliens

Scherrens

, et al. A systematic review of quality improvement initiatives for continuous sedation until death. Palliat Med 2021; 35: 670–682.

van der Heide

Deliens

Faisst

, et al. End-of-life decision-making in six European countries: descriptive study. Lancet 2003; 362: 345–350.

Robijn

Cohen

Rietjens

, et al. Trends in continuous deep sedation until death between 2007 and 2013: a repeated nationwide survey. PLoS One 2016; 11: e0158188.

Seale

Continuous deep sedation in medical practice: a descriptive study. J Pain Symptom Manage 2010; 39: 44–53.

Rietjens

JA.

The rising frequency of continuous deep sedation in the Netherlands, a repeated cross-sectional survey in 2005, 2010 and 2015. J Am Med Dir Assoc 2019; 20(11): 1367–1372.

Putman

Yoon

Rasinski

, et al. Intentional sedation to unconsciousness at the end of life: findings from a national physician survey. J Pain Symptom Manage 2013; 46: 326–334.

Heijltjes

van Thiel

Rietjens

, et al. Changing practices in the use of continuous sedation at the end of life: a systematic review of the literature. J Pain Symptom Manage 2020; 60(4): 828–846.e3.

Rietjens

van Delden

van der Heide

Palliative sedation: the end of heated debate?

Palliat Med 2018; 32(11): 1639–1640.

10.

Raus

Sterckx

How defining clinical practices may influence their evaluation: the case of continuous sedation at the end of life. J Eval Clin Pract 2016; 22: 425–432.

11.

Papavasiliou

Payne

Brearley

, et al. Continuous sedation (CS) until death: mapping the literature by bibliometric analysis. J Pain Symptom Manage 2013; 45: 1073–1082.e10.

12.

van Delden

JJM

Heijltjes

Harwood

RH.

Should we all die asleep? The problem of the normalization of palliative sedation. Age Ageing 2023; 52: afad164.

13.

Raus

Sterckx

Mortier

Is continuous sedation at the end of life an ethically preferable alternative to physician-assisted suicide?

Am J Bioeth 2011; 11: 32–40.

14.

Schildmann

Clinical and ethical challenges of palliative sedation therapy. The need for clear guidance and professional competencies. Int J Clin Pract 2013; 67: 1086–1088.

15.

Heijltjes

Morita

Mori

, et al. Physicians’ opinion and practice with the continuous use of sedatives in the last days of life. J Pain Symptom Manage 2022; 63: 78–87.

16.

Pype

Teuwen

Mertens

, et al. Suboptimal palliative sedation in primary care: an exploration. Acta Clin Belg 2018; 73: 21–28.

17.

Robijn

Deliens

Rietjens

, et al. Barriers in the decision making about and performance of continuous sedation until death in nursing homes. Gerontologist 2020; 60: 916–925.

18.

Robijn

Seymour

Deliens

, et al. The involvement of cancer patients in the four stages of decision-making preceding continuous sedation until death: a qualitative study. Palliat Med 2018; 32(7):1198–1207.

19.

Bruinsma

Rietjens

van der Heide

Palliative sedation: a focus group study on the experiences of relatives. J Palliat Med 2013; 16: 349–55.

20.

Robijn

Towards the improvement of continuous sedation until death in nursing homes. Ghent: Vrije Universiteit Brussel (VUB) and Ghent University, 2020.

21.

Seymour

Bellamy

Gott

, et al. Good deaths, bad deaths: older people’s assessments of the risks and benefits of morphine and terminal sedation in end-of-life care. Health Risk Soc 2002; 4: 287–303.

22.

Twycross

Reflections on palliative sedation. Palliat Care 2019; 12: 1178224218823511.

23.

Robijn

Gijsberts

Pype

, et al. Continuous palliative sedation until death: the development of a practice protocol for nursing homes. J Am Med Dir Assoc 2021; 22(8): 1776.e1–1776.e7.

24.

Kirkham

Davis

Altman

, et al. Core Outcome Set-STAndards for Development: The COS-STAD recommendations. PLoS Med 2017; 14: e1002447.

25.

Zambrano

Haugen

van der Heide

, et al. Development of an international Core Outcome Set (COS) for best care for the dying person: study protocol. BMC Palliat Care 2020; 19: 184.

26.

The COMET Initiative. Core outcome measures in effectiveness trials, https://www.comet-initiative.org/ (2010, last accessed 16 May 2025).

27.

Williamson

Altman

Bagley

, et al. The COMET Handbook: version 1.0. Trials 2017; 18: 280.

28.

Arksey

O’Malley

Scoping studies: towards a methodological framework. Int J Soc Res Methodol 2005; 8: 19–32.

29.

Levac

Colquhoun

O’Brien

KK.

Scoping studies: advancing the methodology. Implement Sci 2010; 5: 69.

30.

Moher

Liberati

Tetzlaff

, et al. Preferred reporting items for systematic reviews and meta-analysis: the PRISMA statement. PLoS Med 2009; 6: 1000097.

31.

Ouzzani

Hammady

Fedorowicz

, et al. Rayyan—a web and mobile app for systematic reviews. Syst Rev 2016; 5: 210. https://doi.org/10.1186/s13643-016-0384-4

32.

QSR International. NVivo (Version 15) [Computer software]. https://www.qsrinternational.com/nvivo-qualitative-data-analysis-software/home (2024).

33.

Bruinsma

Rietjens

JAC

Seymour

, et al. The experiences of relatives with the practice of palliative sedation: a systematic review. J Pain Symptom Manage 2012; 44: 431–45.

34.

McColl

Jacoby

Thomas

, et al. Design and use of questionnaires: a review of best practice applicable to surveys of health service staff and patients. Health Technol Assess (Rockv) 2001; 5: 1–256.

35.

Guyatt

Feeny

Patrick

DL.

Measuring health-related quality of life. Ann Intern Med 1993; 118: 622–629.

36.

Webbe

Sinha

Gale

Core outcome sets. Arch Dis Child Educ Pract Ed 2018; 103: 163–166.

Supplementary Material

Please find the following supplemental material available below.

For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.

For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.

0.00 MB

0.02 MB

0.45 MB