The revised 2023 framework on palliative sedation from the European Association for Palliative Care (EAPC) observes “a shift towards a broader recognition of refractory existential suffering as a possible indication for palliative sedation” (Surges et al. Reference Surges, Brunsch and Jaspers2023). Yet several recent systematic reviews identify unresolved questions about how existential suffering is defined, assessed, and treated in palliative care (Boston et al. Reference Boston, Bruce and Schreiber2011; Ciancio et al. Reference Ciancio, Mirza and Ciancio2020; Rodrigues et al. Reference Rodrigues, Crokaert and Gastmans2018). A lack of clarity and consensus on these questions is likely a barrier to the optimal care of patients with existential suffering at the end of life, as well as a source of misunderstanding and controversy with respect to the use of palliative sedation to treat refractory existential suffering (Boston et al. Reference Boston, Bruce and Schreiber2011; Ciancio et al. Reference Ciancio, Mirza and Ciancio2020; Kirk and Mahon Reference Kirk and Mahon2010; Quill et al. Reference Quill, Lo and Brock2009; Rattner Reference Rattner2022).
In a systematic review, Boston et al. (Reference Boston, Bruce and Schreiber2011) identified 56 unique definitions of existential suffering. As such, it is not surprising that organizational guidelines define existential suffering in broad terms. The EAPC defines existential suffering as “feelings of hopelessness, helplessness, fear of death, disappointment, loss of self-worth, remorse, loss of meaning and purpose in life, disruption of personal identity, or loss of dignity” (Ciancio et al. Reference Ciancio, Mirza and Ciancio2020; Surges et al. Reference Surges, Brunsch and Jaspers2023). Similarly, the National Hospice and Palliative Care Organization (NHPCO) defines existential suffering as that “arising from a sense of meaninglessness, hopelessness, fear, and regret in patients who knowingly approach the end of life” (Kirk and Mahon Reference Kirk and Mahon2010).
Furthermore, some authors differentiate between existential suffering and existential distress. Schuman-Olivier et al. suggest that existential distress is a subtype of existential suffering that occurs in the terminally ill or dying (Schuman-Olivier et al. Reference Schuman-Olivier, Brendel and Forstein2008; Surges et al. Reference Surges, Brunsch and Jaspers2023). By contrast, 1 systematic review cites multiple studies that describe suffering as an “all-encompassing, enduring, and intense experience,” distinct from distress as a “transient or fleeting experience” (Rattner Reference Rattner2022). This article preferentially utilizes the term existential suffering as a broad term that does not imply proximity to death.
Apart from the challenge of defining existential suffering, many authors have raised concerns about the inherent subjectivity and ambiguity in the evaluation of existential suffering (Boston et al. Reference Boston, Bruce and Schreiber2011; Ciancio et al. Reference Ciancio, Mirza and Ciancio2020; Rattner Reference Rattner2022; Rodrigues et al. Reference Rodrigues, Crokaert and Gastmans2018). Patients may face various barriers in expressing their suffering, including the difficulty of finding adequate words, further complicated by time-limited clinical encounters (Best et al. Reference Best, Aldridge and Butow2015; Boston et al. Reference Boston, Bruce and Schreiber2011). For some patients, it may be challenging to distinguish between physical suffering and categories of “nonphysical” suffering such as existential, spiritual, psychological, emotional, and social (Boston et al. Reference Boston, Bruce and Schreiber2011; Ciancio et al. Reference Ciancio, Mirza and Ciancio2020; Rattner Reference Rattner2022). Two systematic reviews identify the use of multidisciplinary teams – such as those with psychological, spiritual, and biomedical expertise – as potentially helpful in assessing existential suffering (Boston et al. Reference Boston, Bruce and Schreiber2011; Ciancio et al. Reference Ciancio, Mirza and Ciancio2020).
Yet another issue is to determine what “refractoriness” means in relation to the use of palliative sedation to treat refractory existential suffering. The EAPC acknowledges that establishing the refractoriness of existential suffering is challenging because “the severity of the distress may be very dynamic and idiosyncratic, and psychological adaptation and coping may occur” (Surges et al. Reference Surges, Brunsch and Jaspers2023). By contrast, the NHPCO considers it a still-unresolved question as to whether palliative sedation should be used to treat existential suffering, and calls for more research to explore alternative interventions (Kirk and Mahon Reference Kirk and Mahon2010). One systematic review observes the lack of a clear theoretical framework for treating existential suffering apart from psychiatric and psychoanalytic approaches (Boston et al. Reference Boston, Bruce and Schreiber2011).
In response to these ongoing challenges, we propose the following as priority areas for research and clinical practice: (1) development and validation of instruments to guide clinicians’ assessments of existential suffering; (2) study of the potential overlap and interplay between existential suffering, other nonphysical forms of suffering, and physical symptoms; and (3) development and evaluation of alternatives to palliative sedation to treat existential suffering.
Development and validation of instruments
The quest for a scale to measure existential suffering is hampered by the absence of any agreed upon definition. Nonetheless, several instruments have been developed that seem to capture aspects of what the literature typically describes under the label, “existential suffering” (Best et al. Reference Best, Aldridge and Butow2015; Boston et al. Reference Boston, Bruce and Schreiber2011). One of the best-known instruments to identify some aspects of existential suffering in patients with advanced illness is the Demoralization Scale (DS) (Kissane et al. Reference Kissane, Wein and Love2004). Kissane et al. developed this 24-item scale to recognize patients who are demoralized but not clinically depressed. The DS identifies several domains of existential suffering, including disheartenment, loss of meaning and purpose, dysphoria, helplessness, and sense of failure. It has been externally validated in its original version as well as several shortened forms (Belvederi Murri et al. Reference Belvederi Murri, Zerbinati and Ounalli2020; Bobevski et al. Reference Bobevski, Kissane and McKenzie2022; Robinson et al. Reference Robinson, Kissane and Brooker2016).
However, apart from identifying patients who experience aspects of existential suffering, the DS and its variants are not designed to prompt specific clinical interventions or referrals. Additionally, these instruments do not evaluate forms of nonphysical suffering – such as spiritual and social suffering – that may closely relate to existential suffering and even fit within some definitions of the term.
Other instruments assess for suffering or distress more broadly. The distress thermometer is a visual analog scale that allows patients to rate their emotional distress (Graham-Wisener et al. Reference Graham-Wisener, Dempster and Sadler2021; Ma et al. Reference Ma, Zhang and Zhong2014; Roth et al. Reference Roth, Kornblith and Batel-Copel1998). A variety of suffering scales – including the suffering pictogram (Beng et al. Reference Beng, Ann and Guan2017), State Of Suffering-Five (SOS-V) (Ruijs et al. Reference Ruijs, Onwuteaka-Philipsen and van der Wal2009), suffering assessment questionnaire (Encarnação et al. Reference Encarnação, Oliveira and Martins2018), and suffering assessment tool (Baines and Norlander Reference Baines and Norlander2000) – capture aspects of existential suffering, yet often as part of a larger assessment of symptom burden and without emphasis on forms of nonphysical suffering. The same is true of the Memorial Symptom Assessment Scale (Portenoy et al. Reference Portenoy, Thaler and Kornblith1994) and the Edmonton Symptom Assessment System (Hui and Bruera Reference Hui and Bruera2017).
Ideally, instruments to guide clinicians’ assessments of existential suffering would consider various forms of nonphysical suffering, including existential, spiritual, psychological, emotional, and social. They would also ask about patients’ coping mechanisms, sources of support, and experiences with previous therapeutic interventions as an important foundation for ongoing clinical evaluation and care (Bovero et al. Reference Bovero, Sedghi and Opezzo2018; Xiao et al. Reference Xiao, Ng and Yan2021).
Study of the relationship between existential and other forms of suffering
Further complicating matters, physical and existential suffering are often knitted together tightly in patients’ experiences. Cicely Saunders’s concept of “total pain” emphasized the fundamental relationship between physical symptoms and forms of nonphysical suffering, which she designated as “mental distress and social or spiritual problems” (Saunders Reference Saunders2001). The NHPCO similarly employs a broad conception of suffering, which “can be the result of injuries to many aspects of the self, including … the physical, psychosocial, spiritual, temporal, and existential realms” (Kirk and Mahon Reference Kirk and Mahon2010).
In addition, the 2023 EAPC framework recognizes that existential suffering includes a number of distinguishable nonphysical components (Surges et al. Reference Surges, Brunsch and Jaspers2023). The framework therefore recommends that existential suffering should only be deemed refractory “following comprehensive assessment by experts in palliative care, considering the psychological, social and spiritual components of suffering” (Surges et al. Reference Surges, Brunsch and Jaspers2023). In other words, assessments of existential suffering should not simply be confined to a narrow construct or definition but shloud broadly examine various and potentially related forms of nonphysical suffering.
One systematic review points out that existential suffering is sometimes understood in the literature to include spiritual, psychological, and social issues – although the literature shows no consistent pattern (Boston et al. Reference Boston, Bruce and Schreiber2011). Another systematic review contrasts Saunders’s and Cassell’s view of “suffering” as integrated and multidimensional with the tendency across multiple studies “that researchers, patients and clinicians distinguish physical from nonphysical aspects of suffering” (Rattner Reference Rattner2022).
Considering this heterogeneous literature, it is imperative for future studies to explore and characterize the potential overlap and interplay among the various nonphysical forms of suffering, as well as the relationship between physical and nonphysical suffering. Otherwise, the conditions for designating a patient’s existential suffering as “refractory” will remain ill-defined and controverted.
Alternatives to palliative sedation for existential suffering
It is often recommended that palliative sedation only be undertaken as a last-resort option, but few studies have explored potential alternatives to palliative sedation. The strongest evidence for treating patients with existential suffering at the end of life comprises various forms of psychotherapy (Bauereiß et al. Reference Bauereiß, Obermaier and Özünal2018; LeMay and Wilson Reference LeMay and Wilson2008; Vehling and Kissane Reference Vehling and Kissane2018). Several of these approaches have demonstrated effectiveness in randomized controlled trials, including meaning-centered group psychotherapy (Breitbart et al. Reference Breitbart, Rosenfeld and Pessin2015) and individual meaning-centered psychotherapy (Breitbart et al. Reference Breitbart, Pessin and Rosenfeld2018), which improved spiritual well-being and quality of life and reduced desire for hastened death; dignity therapy, which improved quality of life and sense of dignity (Chochinov et al. Reference Chochinov, Kristjanson and Breitbart2011); and Managing Cancer and Living Meaningfully (CALM), which alleviated depressive symptoms and improved end-of-life preparation (Rodin et al. Reference Rodin, Lo and Rydall2018). Additional randomized controlled trials are currently underway, including a study involving Meaning and Purpose therapy (Kissane et al. Reference Kissane, Lethborg and Brooker2019).
More broadly, the effects of spiritual, psychosocial, and mind–body interventions for patients with life-limiting illness have been the subject of systematic reviews and meta-analyses (Hall et al. Reference Hall, Luberto and Philpotts2018; McLouth et al. Reference McLouth, Ford and Pustejovsky2021; Oh and Kim Reference Oh and Kim2014; Park et al. Reference Park, Pustejovsky and Trevino2019; Xing et al. Reference Xing, Guo and Bai2018). Overall, these analyses are limited by the heterogeneity of the literature reviewed – for instance, 2 meta-analyses of spiritual interventions for patients with cancer combined psychotherapy interventions with nursing- and oncologist-driven spiritual interventions in their statistical analyses (Oh and Kim Reference Oh and Kim2014; Xing et al. Reference Xing, Guo and Bai2018). Future research is needed to explore the potential effectiveness of interventions other than forms of psychotherapy, including meditation and relaxation techniques (Hall et al. Reference Hall, Luberto and Philpotts2018).
Regarding pharmacologic treatments, there is a growing interest in the potential benefit of ketamine and other psychedelics for the treatment of existential suffering (Decazes et al. Reference Decazes, Rigal and Clatot2023; Niles et al. Reference Niles, Fogg and Kelmendi2021; Schimmers et al. Reference Schimmers, Breeksema and Smith-Apeldoorn2022). However, a stronger evidence base involving larger, high-quality studies is still needed before these approaches can be recommended for clinical use (Niles et al. Reference Niles, Fogg and Kelmendi2021; Schimmers et al. Reference Schimmers, Breeksema and Smith-Apeldoorn2022).
As the evidence grows for alternatives to palliative sedation for patients with existential suffering, a clear framework is needed to guide clinicians as they consider treatment options for their patients (Boston et al. Reference Boston, Bruce and Schreiber2011). Greater development and availability of methods to relieve existential suffering in a timely and safe manner may reduce the number of cases in which existential suffering is considered “refractory” (Surges et al. Reference Surges, Brunsch and Jaspers2023).
Conclusion
Improving the care of patients with existential suffering in palliative care requires better instruments to evaluate existential and other nonphysical forms of suffering, a greater understanding of the potential overlap among various forms of suffering, and the continued development of alternatives to palliative sedation. Greater clarity and capability regarding approaches to existential suffering may change the conversation about whether and when palliative sedation is indicated for these patients.
Funding
Drs. Thomas and Sulmasy are supported by a grant from the McDonald Agape Foundation. Dr. Breitbart is supported by a grant from the National Cancer Institute [grant number 5P30CA008748-55]. The funding sources had no role in design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, or approval of the manuscript.
Competing interests
None of the authors has any conflicts of interest to declare.
