A Brief Literature Review of Conceptual Models in Palliative Care

Abstract

Receiving palliative care has been shown to be effective in older adults with serious illnesses and reducing the healthcare burden and cost. To improve further research on old adults suffering from serious illness, we summarize the currently available theoretical models of palliative care, which could improve care strategies. Notably, few studies have focused on the conceptual models or theoretical frameworks of palliative care. In this review, we summarize the conceptual models or theoretical frameworks based on empirical data or quantitative research in the end-of-life field. We reviewed the theoretical models in the current literature regarding the field of palliative care. A structured data extraction form was used to record whether a study proposed a theoretical/conceptual model. Several conceptual models or theoretical frameworks were presented and summarized. Future endeavors should explore the conceptual models or theoretical frameworks from a holistic perspective in the field of end-of-life care.

1. Introduction

The increase in the aging population worldwide has resulted in the rise of people living with multiple chronic illnesses. It is estimated that the number of Americans aged over 65 years old will be more than 98 million by 2060, approximating 24% of the population in the latter part of the century [1]. Individuals with life-threatening illness pose a substantial burden on healthcare systems and can have a detrimental impact on family caregivers. Advancements in medical technology, particularly in the areas of the detection, pathological diagnosis, and treatment of life-threatening illnesses, have resulted in a growing population of older adults with advanced incurable, and progressively fatal conditions. This trend underscores the urgent need to address the complex challenges associated with the care and support of these individuals, as well as to explore innovative approaches to alleviate their suffering and enhance their quality of life. As a result, patients with advanced illness show poor response to treatment and poor quality of life, and suffer from physical and psychological ailments. This has attracted the attention of authorities and necessitated the development of strategies to improve the care of these patients.

The concept of palliative care has been proposed as an effective intervention that provides active treatment, holistic care, and services for dying patients who have no hope of treatment and whose life expectancy does not exceed 3–6 months. Such an intervention allows the patients to face death calmly, alleviate their pain, and improve their quality of life [2]. Palliative care consists of a multidisciplinary team, comprising primary care physicians, specialty physicians, palliative care specialists, and a supportive ancillary team. Palliative care was first developed by the United Kingdom, which provided a solid theoretical foundation and has a high degree of public participation. Palliative care can alleviate disease and negative psychological emotions, and obtain peace in patients with advanced illness, and provide comfort and dignity in the last days of their life. To promote the development of these domains, the National Institutes of Health (NIH) introduced the concept of developing end-of-life conceptual models in 2004. Subsequently, in the United States, palliative care was predominantly regarded as applicable only during the final 1–2 weeks of life, while medical insurance coverage was limited to hospice care for the last 6 months of life [3]. As of 2017, 48.2% of patients received hospice care [4]. Over the past 30 years, palliative care has shifted from basic hospital care to home care where about a quarter of patients die at home [5]. However, the palliative care remains under-used in the developed nations.

There is a need to develop conceptual models or theoretical frameworks for evaluating research outcomes. The existing body of literature on conceptual models or theoretical frameworks in palliative care is notably limited. Consequently, the objective of this study is to address this research gap by providing a comprehensive summary of conceptual models or theoretical frameworks derived from empirical data or quantitative research in the field of end-of-life care. In this literature review, we aim to enhance the understanding and application of theoretical perspectives in palliative care, facilitating further advancements in the field.

2. Methods

2.1 Search strategies

The search was performed to identify studies published in English in several electronic databases including PubMed, Cochrane Library, EMBASE, Web of science. Two reviewers independently evaluated eligible papers from inception to July 1, 2023 and any discrepancies were resolved by a third investigator. To avoid omission, search terms comprising the following terms were used (e.g., Medical Subject Headings (Mesh)): (palliative care (Mesh) or Care, Palliative or Palliative Treatment or Palliative Treatments or Treatment, Palliative or Treatments, Palliative or Therapy, Palliative or Palliative Therapy or Palliative Supportive Care or Supportive Care, Palliative or Palliative Surgery or Surgery, Palliative) and (Models, Theoretical (Mesh) or Model, Theoretical or Theoretical Model or Theoretical Models or Models, Theoretic) and (Aged (Mesh) or elderly).

The complete search strategy was shown below:

((((((((((((((“Palliative Care”[Mesh]) OR (palliative care [Title/Abstract])) OR (Care, Palliative [Title/Abstract])) OR (Palliative Treatment [Title/Abstract])) OR (Palliative Treatments [Title/Abstract])) OR (Treatment, Palliative [Title/Abstract])) OR (Treatments, Palliative [Title/Abstract])) OR (Therapy, Palliative [Title/Abstract])) OR (Palliative Therapy [Title/Abstract])) OR (Palliative Supportive Care [Title/Abstract])) OR (Supportive Care, Palliative [Title/Abstract])) OR (Palliative Surgery [Title/Abstract])) OR (Surgery, Palliative [Title/Abstract])) AND ((((((“Models, Theoretical”[Mesh]) OR (Models, Theoretical [Title/Abstract])) OR (Model, Theoretical [Title/Abstract])) OR (Theoretical Model [Title/Abstract])) OR (Theoretical Models [Title/Abstract])) OR (Models, Theoretic [Title/Abstract]))) AND (((“Aged”[Mesh]) OR (Aged [Title/Abstract])) OR (Elderly [Title/Abstract]))

2.2 Article screening and selection

Endnote X9 was employed to effectively manage all the collected data in this study. Two reviewers conducted independent searches for eligible articles and meticulously screened the titles, abstracts, and full texts for inclusion. In the event of any discrepancies, a third investigator (XY) was involved to resolve conflicts. A detailed overview of the literature screening process is illustrated in Figure 1.

Figure 1.

The flow chart of literature screening.

3. Results

The conceptual models or theoretical frameworks are presented in Table 1. In addition, the components or indicators applied in the models were displayed as follows:

No.	Authors	Years	Type	Design	Sample	Models or theory	Method	Endpoint	Instruments
1	Buck et al.	2009	Article	Quantitative study	Participants (n = 403)	Symptom experience-- > QoL; Spiritual experience-- > QoL; Emanuel and Emanuel’s (1998) framework of a good death	Structural equation model	Quality of life (QoL)	Scales
2	Harding et al.	2019	Article	Interview	Family caregivers (n = 100); Patients (n = 24)	Communication--family--patients	Grounded theory	Outcomes of actions as responses to an event	Coding
3	Meeker et al.	2013	Article	Face-to-face, semi-structured interviews	Family surrogates (n = 100); Patients (n = 12)	Suffering-struggling--setting	Grounded theory	Outcomes of actions as responses to an event	Coding
4	Moorhouse et al.	2012	Article	Quantitative study	Participants (n = 150)	Palliative and therapeutic harmonization (PATH)	Grounded theory	Outcomes of actions as responses to an event	Scales+coding
5	Bone et al	2016	Article	Quantitative study	Participants (n = 80)	Short-term integrated palliative and supportive care (SIPS)	Observational study design	Outcomes of actions as responses to an event	Coding
6	Jerant et al	2004	Article	Quantitative study	Participants (n = 78)	Timely and team oriented, longitudinal, collaborative, and comprehensive (TLC) Model	A nonblinded, prospective comparison trial	Quality of life (QoL)	Questionnaire
7	Murray et al	2007	Review	None	None	Transitions model of palliative care (TMPC)	None	None	None
8	Emanuel et al	1999	Review	None	None	Good health model	None	Overall experience of the dying process	None
9	Bull et al	2017	Article	None	None	Community-based palliative care (CBPC)	None	None	None

Table 1.

Summary of conceptual models or theoretical frameworks in the palliative care.

3.1 Framework of a good death

This framework improved our understanding of the dying experience and the quality of care in the end-of-life field [6]. It comprised four components: the fixed characteristics of the patients; the modifiable dimensions of the patient’s experience; care-system interventions; and outcomes. This framework helped clinicians to conduct comprehensive assessments for end-of-life patients. Additionally, the framework could help promote the relevant research at the end of life.

3.2 Geriatric cancer experience at the end of life

An adapted model named “the geriatric cancer experience at the end of life” was established on the basis of the Framework of a Good Death. Buck et al. reported that the framework of a good death had two limitations: the absence of measurable outcome indicators and their linear relationships among various components. He suggested that linear relationships between clinical status, physiological, psychological, and spiritual components, and quality of life [7]. Finally, he emphasized the significance of physical and spiritual domains in evaluating the quality of life in geriatric end-of-life care.

3.3 The model for the family caregivers’ experience in providing care

This model primarily examines the experience of family caregivers, encompassing various aspects of their caregiving journey, including challenges, consequences, and motivations. It proposed that caregiving was the key factor influencing the family caregivers’ experience [8]. A comprehensive understanding of family caregivers’ experience was presented in a structured way. Elsewhere, Meeker et al. investigated patients’ and caregivers’ experiences during with the management of advanced illness [9]. He depicted a transitional process involving suffering, struggling, and settling phases. Additionally, scholars have developed an explanatory model to understand the potential mechanisms behind communication deficits among family caregivers, patients, and clinicians [10].

3.4 The Markov multistate model of performance status

Multistate models were primarily used to summarize the complex changes associated with disease progression [11, 12]. Sutradhar et al. used the Markov multistate model to explore relevant and important information for the utility of the palliative care services [11].

3.5 Management models for palliative care

Short-term integrated palliative and supportive care (SIPS) was developed for frail older people in the community to improve symptom management [13]. Jerant et al. proposed the TLC model, which comprises timely, team-oriented, longitudinal, collaborative, and comprehensive [14]. The TLC model was defined as the palliative care which is in line with the SIPS model. In 2003, the Four Seasons community-based palliative care (CBPC) program was established. It aimed to develop a longitudinal delivery model that integrates an interdisciplinary team to provide comprehensive care for patients with life limiting [15].

3.6 Palliative and therapeutic harmonization (PATH) model

Additionally, PATH model was constructed to assess frailty when making medical decisions [16]. This model showed good performance in various scenarios.

4. Discussion

This brief review summarizes empirical studies on theoretical or conceptual models in geriatric end-of-life care. In future, researchers should pay careful attention to various theoretical and conceptual issues.

4.1 Theoretical issues

Theoretical frameworks are important for guiding the development of knowledge or the explanation of a phenomenon. These theoretical models can guide clinical research, but the lack of such models is an issue in end-of-life research. This review obtained theoretical frameworks primarily focusing on the transition of disease state, experience of family caregivers or patients, and holistic approaches to palliative care management.

4.1.1 The model of disease state

Multistate models have been used to describe the complex changes during the course of a disease [17]. In previous clinical research, a common approach was to conduct survival analysis using two outcome indicators: “alive” and “dead.” This represents the simplest form of a multistate model. Another well-known multistate model is the illness-death model, also known as the disability model, which comprises three states: disease-free, diseased, and dead [18]. Multistate models are versatile tools for assessing the probability of patient transitions between different states. These models offer valuable biological insights to physicians, aiding them in making informed clinical decisions [19].

4.1.2 The model focused on patients or family caregivers

The essence of end-of-life care is to relieve patients’ suffering, which needs to be a transition from cure-focused interventions to comfort-focused care. Therefore, palliative care is essential to be people-oriented services involving several domains, such as physical, psychosocial, and spiritual domains. Scholars have proposed conceptual models to enhance our understanding of patients’ or caregivers’ experience. However, limited research exists on conceptual models in palliative care, hindering the development of theoretical frameworks in this area. More quantitative and qualitative research should be needed to investigate the potential influence factors on participants in the whole process of end-of-life care, aiming to develop feasible comfort-focused interventions.

4.1.3 The model focused on incorporating with multidisciplinary

End-of-life care, characterized by holistic, interdisciplinary, and comfort-focused services, is crucial for individuals facing advanced illnesses. Therefore, the implementation of palliative care services is faced with several challenges for older people with life-threatening illness. Scientists acknowledge the importance of investigating the provision of feasible and appropriate palliative care for individuals with advanced illness [13]. An ideal theoretical framework for multidisciplinary management can offer valuable guidance to enhance the quality of life for older individuals.

4.2 Methodological issues

Grounded theory approach is the most common method for qualitative research, which can be widely used to explore theory building or conceptual thinking [20]. This method is an inductive process since a theory is derived from data, rather than a deductive reasoning process. The grounded theory is drawn from sociology, which focuses on studying human behavior on a specific topic by conducting a series of interviews. The interviews contain several forms, such as structured interviews, semi-structured interviews, group interviews among others. Another leading analytical strategy is the structural equation model (SEM), which is useful in empirical research [21]. SEM models can be applied in sociology, psychology, economy, and marketing research. SEM outperforms other statistical approaches owing to its ability to analyze complex, multidimensional, and empirical data inclusive of abstract concepts or theoretical constructs. Prior to constructing SEM models, researchers must ensure that all necessary theoretical assumptions have been established in the analysis. Therefore, the utilization of theoretical frameworks or conceptual models derived from empirical data is essential for implementing the SEM approach.

5. Conclusion

While significant progress has been made in implementing palliative care for advanced illness, further research is required to explore holistic conceptual models and theoretical frameworks in the end-of-life field. Specially, there is a need for empirical studies aimed at alleviating suffering.

Acknowledgments

In addition, I wish to acknowledge the following funds: 1. Yunnan Rehabilitation Clinical Medical Center, zx2019-04-02; 2. Research on a new Model of comprehensive Intervention in Rehabilitation and Psychology of Brain and Heart, 202203AC100007-6; 3. Jia Jie Expert Workstation, 202305AF150032.