Palliative care is considered a basic human right for all patients with chronic and life-threatening illnesses (Ezer et al., 2018). This applies particularly to patients with cancer (Heins et al., 2018)- a leading cause of mortality resulting in 10 million deaths in 2020 (World Health Organization, 2020). The objective of palliative care is to manage symptoms and improve the quality of life of patients in the physical, psychological, spiritual, and psychosocial domains (Khater et al., 2021). Despite the provision of palliative care, several unmet needs remain for patients with advanced illnesses (World Health Organization, 2020). A systematic review finds that psychological, physical, and healthcare information and services are the three most commonly reported domains of unmet needs among Chinese patients with advanced cancer (Wu et al., 2022). Another systematic review (Wang et al., 2018) specifically identifies the unmet care needs of patients with terminal cancer. These needs include the appropriate management of physical pain as an example of an unmet physical need, and perceived reduction in autonomy as an example of unmet psychological need, often expressed as “not being able to do the things I used to do,” “I can do less than before,” and “experiencing loss of control over my life.” Additionally, unmet social needs for companionship include lack of “family and friends’ support”, not “having one member of hospital staff with whom I can talk to,” and “support in coping.” These unmet needs have been documented to have a detrimental effect on the progression of illnesses and consequently the quality-of-life of patients with terminal diseases (Spitzer et al., 1995; Katon, 2003; Cohen, 2004; Fink et al., 2004).

Evidence-based medical treatment and non-pharmacological interventions have both been used to manage symptoms in palliative care. Without the side effects of medical treatment, psychological interventions are widely delivered. Relaxation plays a central role in cognitive-behavioral therapy and has been found to be an effective tool for psychological interventions (Barlow et al., 1989; Norton and Price, 2007; Tsitsi et al., 2017). They are cost-effective, practical, and free of side effects (McCallie et al., 2006; Lin et al., 2011). Numerous studies have confirmed the effectiveness of relaxation techniques for managing cancer-related symptoms (Simeit et al., 2004; de Carvalho et al., 2007; Kwekkeboom et al., 2008; Matsuda et al., 2014; Stoerkel et al., 2018; Berkman and Akan, 2019; Dikmen and Terzioglu, 2019). Diaphragmatic breathing is an example of such a technique. It refers to a breathing technique that involves the contraction and relaxation of the diaphragm muscle. Unlike shallow chest breathing, diaphragmatic breathing intentionally expands the abdomen for deeper inhalation and exhalation, resulting in physiological and psychological benefits. It can relax the autonomic nervous system by enhancing parasympathetic activity (Lazarus and Mayne, 1990). It is found to improve attention, reduce negative affect, and alleviate stress responses (Ma et al., 2017).

Despite the abundance of evidence indicating the effectiveness of relaxation for symptom management, most studies concentrate solely on traditional techniques. Only a few studies have integrated advanced technologies, such as virtual reality (VR), with traditional relaxation methods (Chirico et al., 2016). VR is a cutting-edge technology that has the potential to make up for the shortcomings of traditional approaches in palliative care settings. It creates an immersive experience that can generate a sense of presence in a virtual environment (Malloy and Miling, 2010; Cummings and Bailenson, 2016; Berkman and Akan, 2019). It has become increasingly popular in complementary medicine because its unique characteristics can overcome certain limitations of traditional therapy (Stetz et al., 2011; Morina et al., 2015). First, VR offers an immersive environment that blocks patients from seeing their physical surroundings while instead inducing a sense of presence (“being there”) in a controlled, virtual environment (Slater, 2009). One of the most important cognitive-behavioral techniques for reducing pain is distraction, as suggested by gate control theory (Melzack and Wall, 1965). The sense of presence within the virtual environment can provide a high level of distraction from reality, which is likely one of the reasons why VR has been shown to be effective in reducing pain (Hoffman et al., 2006). Various studies have provided further evidence that consistently reported on patients’ feelings of being distanced from their current suffering during VR experiences (Schneider et al., 2004; Baños et al., 2013; Lloyd and Haraldsdottir, 2019; Niki et al., 2019; Weingarten et al., 2019; Ferguson et al., 2020; Johnson et al., 2020; Brungardt et al., 2021). Given its therapeutic potential in pain and mood management, VR has been further considered a potential substitute for analgesia (Bani Mohammad and Ahmad, 2019; Wittkopf et al., 2020). Second, VR allows a customized selection of virtual environments that can be tailored to meet the individual needs of patients (Perna et al., 2021). This personalized approach allows VR to overcome certain limitations of traditional therapy. For example, it enables patients to select their preferred VR content for relaxation purpose or even fulfill their wishes of traveling, albeit virtually. A case report (Woo and Lee, 2023) reported the therapeutic potential of using freely available videos from the internet as relaxation material to fulfill the participant’s last wishes of traveling to Japan to enjoy the blossoming season of sakura. Third, VR can induce positive emotions in patients faced with existential challenges. Lloyd and Haraldsdottir’s (2019) pilot study reported on patients’ positive experiences, such as joy and happiness, while using VR as a means to temporarily escape from their real and current situation. Since VR is able to simulate a wide range of environments and sensory experiences with remarkable accuracy, it allows patients to select the virtual environment that maximizes their positive emotions (Woo and Lee, 2023).

Although the three most recent systematic reviews support the potential use of VR in palliative care (Carmont and McIlfatrick, 2022; Martin et al., 2022; Mo et al., 2022), there remains a significant gap in research and clinical practices. Martin et al. (2022) report that most VR studies are related to feasibility or are pilot studies with a small sample size and thus call for a randomized controlled trial with adequate power. The importance of delivering meaningful VR interventions to participants is also highlighted in this review, noting that VR activities that are meaningful for the patient are associated with better outcomes. Ma et al. (2021) similarly stress the importance of conducting high-quality randomized controlled trials to validate the effectiveness of VR as a modality of treatment. They also emphasize the necessity of standardizing programs and procedures to promote the widespread adoption of VR in palliative care. Carmont and McIlfatrick (2022) advocate for a comparison between VR therapy and complementary therapies within the context of palliative care. Geraets et al. (2021) express a similar viewpoint, stating that well-designed studies are necessary to explore the efficacy, efficiency, and cost-effectiveness of VR interventions in comparison to existing treatments.

To fill the gap in both clinical practice and research, we developed a novel VR psychological intervention called Flourishing-Life-Of-Wish Virtual Reality Therapy (FLOW-VRT)®. FLOW-VRT is a structured and personalized psychological intervention specially designed for patients in need of palliative care. Its theoretical foundations are based on flow theory (Csikszentmihalyi, 1975), which proposes the psychological state of flow “in which an individual is completely absorbed in activity without reflective self-consciousness but with a deep sense of control” (Engeser et al., 2021, p.2); self-determination theory, which promotes autonomy and sense of control (Deci and Ryan, 2000); stress coping theory, which advocates the employment of various cognitive and behavioral strategies to adapt to stressful conditions (Lazarus and Folkman, 1984); and attention restoration theory, which posits that an exposure to natural environments helps replenish cognitive resources and enhance wellbeing (Kaplan, 1995; Kaplan, 2001). The primary objective of FLOW-VRT is to address patients’ palliative needs by alleviating physical and emotional distress as well as enhancing the quality of end-of-life. “FLOW-VRT-Relaxation” refers to a specialized version of our FLOW-VRT intervention that focuses on relaxation. It allows patients to choose their preferred VR relaxation experience. In a recent case report (Woo and Lee, 2023), we found initial evidence supporting its feasibility and therapeutic potential. Using a randomized controlled trial, the current study compares FLOW-VRT-Relaxation with traditional relaxation practice. We aim to test the efficacy of FLOW-VRT-Relaxation in effective symptom control, i.e., improved emotional and physical symptoms, when compared with traditional relaxation practice.

Eligible participants from a palliative care unit in a public hospital were recruited from November 2022 to September 2023. During the recruitment period, 140 patients were eligible and approached for the study, with 128 (91%) agreeing to participate. Through randomization, 64 were assigned to the experimental group, and 64 were assigned to the control group. The overall completion rate is 93%, with 59 [92.2%] participants from the experimental group and 60 [93.8%] participants from the control group completing the session. Reasons for incomplete sessions include lack of interest in continuing VR intervention, unfavorable physical conditions such as coughing and tiredness, interruptions such as family visits and early discharge, and needs assessed to be null for VR intervention. The mean and standard deviation ages of the 128 randomized participants are 66.6 and 11.5 years, respectively. 90 of 128 recruited participants [70%] are female, while 38 [30%] are male. The majority of participants completed at least primary education (120 participants [93.8%]). There are no significant differences between groups in terms of age [t(126) = 0.183, p = 0.855], education [χ2(4) = 1.24, p = 0.871], gender [χ2 (1) = 0.599, p = 0.439] and medical treatment [χ2 (4) = 7.43, p = 0.115]. Similarly, there are no significant differences between groups at baseline in CESAS-Total score [t(117) = 0.695, p = 0.488], CESAS-Physical Subscale score [t(117) = 0.401, p = 0.689], and CESAS-Emotional Subscale score [t(117) = 0.324, p = 0.746]. Please refer to Figure 2 for the CONSORT study flow diagram and Table 2 for the baseline characteristics of participants. ANCOVA with the baseline assessment as covariates was conducted to determine if FLOW-VRT-Relaxation would bring about more symptom reduction when compared with a traditional relaxation practice. The ANOVA assumptions were assessed for the total score, physical subscale score, and emotional subscale score. The results of Shapiro-Wilk tests show that the total score (p = 0.112) and physical subscale score (p = 0.182) are normally distributed, but not the emotional subscale score (p < 0.05). Kruskal-Wallis test, as a non-parametric test, was then conducted to analyze the emotional subscale score. The assumption of homogeneity of variances was examined using Levene’s test, which indicates no significant differences for the total score [F(1, 117) = 0.634, p = 0.427], emotional subscale score [F(1, 117) = 0.007, p = 0.934], and physical subscale score [F(1, 117) = 1.88, p = 0.173].

The ANCOVA results show significant differences between the experimental and control groups on the total score [F(1, 116) = 11.3, p = 0.001, η p 2 = 0.09] and physical subscale score, [F(1, 116) = 5.42, p = 0.022, η p 2 = 0.05] (see Figure 3). Post hoc tests report a significantly lower total score (MD = 4.54, p = 0.001, d = 0.618), and the physical subscale score (MD = 2.18, p = 0.02, d = 0.427) for the experimental group. The Kruskal-Wallis test results show a significant difference in the emotional subscale score [H(1) = 8.94, p = 0.003, ϵ 2 = 0.03]. Please refer to Table 3 for the baseline and post-test results of each group and Table 4 for the results of ANCOVA or Kruskal-Wallis test following assumption check.

The current study compares the efficacy of FLOW-VRT-Relaxation with respect to traditional relaxation practice in a palliative care setting. FLOW-VRT-Relaxation shows a significant difference in the reduction of the total score [F(1, 116) = 11.3, p = 0.001, η p 2 = 0.09], physical subscale score [F(1, 116) = 5.42, p = 0.022, η p 2 = 0.05], and emotional subscale score [H(1) = 8.94, p = 0.003, ϵ 2 = 0.03] with respect to traditional relaxation administered in a clinical setting. Significant pre-post treatment effect sizes between the two groups are medium ( η p 2 = 0.09) for the total score and small for both the physical ( η p 2 = 0.05) and emotional subscale score ( ϵ 2 = 0.03) (Cohen, 1988), reflecting a substantial superiority of FLOW-VRT-Relaxation especially with regard to total symptom improvement. The result appears consistent with the data pooled across 8 studies in a recent systematic review conducted by Mo et al. (2022) which demonstrates the significant differences in symptom improvement led by the VR group; however, six out of these eight studies have no comparative arm in their research design. The randomized controlled trial design of our study provides a sound methodological apparatus capable of demonstrating the advantages of complementing traditional relaxation techniques with an immersive VR experience.

The therapeutic elements of FLOW-VRT-Relaxation that are particularly useful in reducing the emotional and physical symptoms among patients with terminal illnesses may relate to its theoretical frameworks. First, FLOW-VRT-Relaxation may have the potential to enhance patients’ self-determination, which requires future investigations to establish the potential relationship. Self-determination theory is “centrally concerned with the social conditions that facilitate or hinder human flourishing” (Ryan and Deci, 2017, p. 6). It is a psychological theory that appraises behavior as a function of motives, taking the form of desires, values, and goals (Deci and Ryan, 2000). Research shows that autonomy-supportive interactions are effective in motivating individuals to adopt healthier behaviors, in contrast to methods that aim to control or regulate the person (Ryan et al., 2008; Ryan et al., 2011). The therapeutic benefits of FLOW-VRT may relate to customization, allowing patients to choose the content used during the experience according to their desires and values. The findings of a systematic review by Martin et al. (2022) resonate with the current study, revealing the therapeutic potential of customized content. Specifically, the review highlights a pattern across the statistical results in which significant somatic and psychological symptom improvement was observed when the VR experience was personally meaningful. Second, FLOW-VRT-Relaxation incorporates VR technology, which has been shown to be flow-inducing (Gaggioli et al., 2003). Although limited studies are exploring the direct effect of flow experiences induced by VR on symptom control in palliative care, it is known that flow is associated with both physical and psychological wellbeing (Persson, 1996; Heo et al., 2010; Hirao et al., 2012; Heo et al., 2013). Future research is, therefore, recommended to substantiate the role of flow in symptom management among patients with terminal illnesses. Lastly, FLOW-VRT-Relaxation may offer opportunities for patients to explore and cultivate adaptive stress coping. The stress coping theory posits the existence of two coping strategies: problem-focused coping, which refers to a coping style concentrating on the management of stressful situations by operating on the stressor, and emotion-focused coping, which aims to manage one’s emotions when facing that stressor (Lazarus and Folkman, 1984). FLOW-VRT-Relaxation allows patients to experience positive emotions derived from the virtual experience, which is clinically meaningful when the stressful condition of being terminally ill may not allow room for problem-focused coping. Such emotion-focused coping is further supported by the findings of Carmont and McIlfatrick’s (2022) systematic integrative review. Their study highlights the potential of VR to foster emotional connection, particularly in the context of patients dealing with terminal illnesses and the accompanying physical and emotional decline.

The current study tested the efficacy of FLOW-VRT-Relaxation by comparing it to traditional relaxation practice in palliative care. Our results show that following a FLOW-VRT-Relaxation session, the symptoms of distress that patients in palliative care typically report significantly reduce, whether physical or emotional in nature. It provides promising evidence that the newly developed FLOW-VRT-Relaxation is preferable as a novel relaxation practice in palliative care. It is hitherto the first personalized VR relaxation intervention guided by theories and clinical considerations on the purpose and content of VR, how VR is to be delivered, and by whom it is delivered. It is also the first VR relaxation intervention empirically tested in a randomized controlled trial with an adequate sample size and compared with traditional relaxation practice in a palliative care setting. The encouraging result of the current research may shed light on the potential application of FLOW-VRT-Relaxation in wider adoption, such as elderly homes and rehabilitation centers. With its optimal use, FLOW-VRT-Relaxation hopefully serve as a complementary therapeutic tool that effectively improves end-of-life care in face of the mounting need of palliative care.