Meaning in life and quality of life: comparison between palliative care patients and a representative sample of the Swiss population

Background and objectives Existential areas, and in particular the concept of meaning in life, represent a key topic in palliative care. The aims of this study are to explore (i) the differences in perceived meaning in life (MIL) and in the meaning-relevant life areas between a representative sample of the Swiss population and palliative care patients, and (ii) to what extent MIL can be considered as a significant predictor of quality of life (QOL) in the two populations. Methods A cross sectional study was conducted separately for the patients (face-to-face interviews) and the representative sample of the Swiss population (telephone survey). MIL was measured with the Schedule for Meaning in Life Evaluation (SMILE) and QOL with a with a single item visual analogue scale (0-10). Socio-demographic variables were controlled for in the analyses. Results 206 palliative care patients and 1015 participants from the Swiss population completed the protocol. Results indicated high MIL scores in both population even if the difference was significant (patients 81.9 vs general population 87, p<.001). Compared to the Swiss population, patients were more likely to cite “family” (OR=1.78), “social relations” (OR=1.9), “spirituality and religion” (OR=3.93), “social commitment” (OR=1.94), and “growth” (OR=2.07), and less likely to cite “finances” (OR=0.15) and “health” (OR=0.21) as MIL-relevant areas. The SMILE scores and MIL areas explained 21.8% of the QOL variance for the palliative care patients and 15.1% for the representative sample. Conclusions Our data emphasize the importance of MIL as a contributor to QOL in both clinical and non-clinical settings. From a clinical perspective, it highlights the importance of the life areas contributing to MIL, in particular the social interactions, since they play a significant role for the patients’ QOL.


Introduction
The concept of Quality of Life (QOL) is the central outcome measure in palliative care research (1).
The World Health Organization (WHO), defines QOL as "the individual perception of the position in life in the context of the culture and value system in which they live, and in relation to their goals, expectations, standards and concerns" (2). In palliative care research, focusing on a general individual perception of QOL, as defined by the WHO, by using a single item question is still relatively uncommon. Many instruments used for research were either designed using a "health-related" concept of QOL (3) or a multidimensional perspective considering different domains (e.g. physical, psychological, social and existential) potentially contributing to QOL (4,5). Several studies have shown in recent years that QOL at the end of life is closely linked to non-physical determinants (6)(7)(8).
Amongst these, the existential domain appears to be particularly relevant for palliative patients (4,9).
Currently, the concepts of "existential" and "spiritual" issues are often used interchangeably in the literature (10). Based on a report of a consensus conference, spirituality is defined as "the aspect of humanity that refers (i) to the way individuals seek and express meaning and purpose, and (ii) the way they experience their connectedness to the moment, to self, to others, to nature and to the significant and sacred" (11). Meaning in life (MIL) therefore represents a core element of spirituality. Existential distress, characterized by a loss of MIL, represents an important clinical issue, as it has been associated with several important outcomes in the end of life context: anxiety and depression (12,13), suicidal ideas (14), the desire for hastened death (15), as well as various distressing physical symptoms (16).
From a clinical point of view, most of the interventions designed to address existential distress consider MIL as a highly individual construct, which is difficult to capture from an external standpoint (17). The identification of life areas contributing to MIL may represent a crucial point when initiating a therapeutic process with patients showing existential suffering (18). Several instruments were developed in order to identify these life areas (19). Among the few instruments using an idiographic approach, the Schedule for Meaning in Life Evaluation (SMILE) allows individuals to choose freely the life areas that they consider important for their own MIL (20).
We studied a representative sample of the Swiss population and a sample of Swiss palliative care patients using the SMILE (6,21). Comparing the two populations may contribute to identify specific MIL areas contributing to QOL as the end of life context that could benefit from psychological interventions. In analogy to the study of Fegg et al. (22) in a German sample, we would like to compare the two Swiss populations (taking into account possible differences between linguistic regions), and additionally explore whether MIL can predict QOL in palliative care patients.

Methods
The data for this comparison study were collected separately for the palliative care patients and the representative sample of the Swiss population. Collection methods and part of the results have been published (6,21).
Briefly, data from of a representative sample of the general population in Switzerland were collected through a telephone survey performed by a professional survey company (21). For palliative care patients, an exploratory, cross-sectional study, based on structured face-to-face interviews, was conducted in all three Swiss linguistic regions (6). Both studies included assessment of MIL, QOL, health status and sociodemographic data (gender, age, education, employment, marital status, residence and linguistic region).

· The Schedule for Meaning in Life Evaluation (SMILE)
This instrument was developed and validated by Fegg et al. (20). Respondents are first asked to indicate three to seven areas that provide meaning to their life. The relevant areas contributing to MIL were classified in one of 15 categories based on a German nationwide survey and reported in a specific manual developed for this instrument. They include: family, partnership, social relations, occupation/work, leisure time/relaxation, home/garden, finances, spirituality/religion, health, satisfaction, nature/animals, social commitment, hedonism, art/culture, and growth (for details on the categories and the SMILE administration see Ref. 6 and www.psychotherapiemuenchen.de/downloads/SMiLE_Manual.pdf).
The importance and the current level of satisfaction associated to each area are rated on Likert scales (seven points, from -3 to +3, for the satisfaction, and eight points, from 0 to 7, for the importance).
An "index of weighting" (IoW ,range 0-100) and an "index of satisfaction" (IoS, range 0-100) indicate the mean weighing score and the mean satisfaction score for the areas mentioned, respectively. A SMILE total score, "index of weighted satisfaction" (IoWS, 0-100) indicates the global MIL satisfaction.

· Subjective QOL Single-item
In both groups, subjective QOL was measured after completion of the SMILE questionnaire with the Single-item Quality of Life Scale -Numeric Rating Scale 0 -10 (SQOLS), ranging from 0 (worst imaginable quality of life) to 10 (best imaginable quality of life). This approach to measuring quality of life was validated by de Boer et al. and Idler et al. (23,24).

Statistics
Differences between sociodemographic characteristics of the two samples were assessed using the chi-square test. The mean of the different SMiLE scores was computed in both samples, and linear regression models were used to determine whether sample membership could explain the scores, controlling for sociodemographic factors. The distribution of MIL areas cited by the respondents was computed separately for each sample. A logistic regression model was computed to assess the presence of each MiL area in function of the sample membership.
After having applied bivariate analyses (t-test and correlation), we built models explaining the subjective QOL from the SMILE scores. We began by considering the full sample, and then we built separate models for the patient and the general population samples. In each case, we proceeded in two steps: In the first one, we used only the three main scores of the SMILE as predictors (IoS, IoW, IoWS). In the second one, we also included indicator variables of the presence or not of the 15 different MIL areas, and we applied a backward selection procedure in order to identify the best model. All models were controlled for socio-demographic characteristics (age, gender, marital status, and education).
The type I error was set to 0.05 for all inferential computations. Statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) version 24.  Table 1 gives the sociodemographic and medical characteristics of the two populations. Results showed significant differences between the two populations regarding age, marital status, and education level. However, effect sizes can be considered as small given the Cramer's V (between .016 and .180). Cancer was the most common diagnosis among the palliative care patients.

Differences in MIL between palliative care patients and the Swiss sample
Results of the linear regressions indicated significant differences between the two populations regarding the index of satisfaction (IoS), the index of importance (IoW) and the SMILE total score (IoWS), with lower scores in the patients sample. On the other hand, no difference was found regarding the number of cited areas.

[Insert table 2]
Differences in sources of MIL between palliative care patients and the Swiss sample "Family" and "social relations" were the two most cited areas in both populations (76% for family in the two populations and 49% vs 39% for the "social relations" in the patients and the Swiss sample respectively). The relational dimension represents therefore the most important dimension for MIL in the two populations. The results of the logistic bivariate regression model show that patients were significantly more likely to cite "family" (OR=1.78), "social relations" (OR=1.9), "spirituality and religion" (OR=3.93), "social commitment" (OR=1.94), and "growth" (OR=2.07), and less likely to cite "finances" (OR=0.15) and "health" (OR=0.21) (see table 3).

[Insert table 3]
Notice that the apparent inconsistency between the percentages and the odds ratio for the family category is due to the fact that the regression model was controlled for sociodemographic factors, which was not the case for the percentages. In particular, there were significant associations between marital status, age and civil status.

MIL as a QOL predictor
The results of the independent samples t-test indicated a significant difference in QOL between the palliative care patients and the Swiss sample (M=5.03, sd=2.6; M=7.56, sd=1.7 respectively; t=17.549, p=.000). The correlation values between QOL and the SMILE scores indicated that these two dimensions were not independent and therefore justified the use of linear regressions to test in which measure MIL was associated with QOL (Pearson correlation values were between .220 and .364, p=.000).
The differences between the two populations clearly warranted a separate analysis in order to obtain a better identification of the QOL predictors. Therefore, we performed regression analyses on the two samples separately.

Discussion
To the best of our knowledge, this study is only the second one that aims to explore differences in MIL between a palliative care population and a representative sample of a population from a national survey, after the study of Fegg et al. (22). The latter study took place in Germany, a more homogeneous socio-cultural context that Switzerland with its mix of German and Latin populations. A novel purpose of our study was to explore the relationship between MIL and the QOL in these two populations.

Level of satisfaction in MIL: the meaning-making hypothesis
The high levels reported in the SMILE total scores in both populations (> 80) are comparable with those found in other studies including different kind of populations: cancer patients (25,26), palliative care patients (27,28), and general populations (22,29). In all these studies, scores ranged between 70 and 80. This propensity towards high SMILE total scores is also apparent in a study with Indian palliative care patients (30). Different meaning-making processes have been described and proposed in the psychological literature, for example using assimilation and accommodation (36). These processes contribute to decrease the discrepancy between a global meaning, consistent with the personal sense of identity, and a situational meaning that arises in the context of a stressful life event. It is possible that such an adaptation or adjustment process may explain the low difference between our two samples. This adjustment hypothesis is made plausible by the fact that most palliative care patients had received their illness diagnosis several months prior to the study, thus allowing for a timeframe for adjustment. This hypothesis requires confirmation in a longitudinal study.
Meaning relevant areas: differences between groups as marks of an adaptation process "Family" and social relations" appear to be the most important domains contributing to MIL in both groups, with the addition of "occupation and work" which is the second most cited area in the Swiss general population. Compared with the general population sample, patients were more likely to cite "family" and "social relations" as relational areas, and "growth" and "spirituality" as psychoexistential areas. An over representation of spirituality and relationship as areas contributing to MIL in palliative care patients was also found in the study of Fegg et al. (22). Conversely, the Swiss representative sample was more likely to mention "finances" and "health" compared with the palliative care patients.
Relationships and spirituality also appear in several studies exploring the sources of MIL by using methodologies other than the SMILE (37)(38)(39). The social relationship dimension was also found to be prominent in advanced cancer patients of different European countries (Spain, Switzerland and Germany) (25), as well as in India (30). In the general population, social integration concerns not only QOL but also survival (40). In the end of life context, a recent systematic review reported the effectiveness of palliative care interventions enhancing social support on the patients' psychological wellbeing (41). Our results also speak in favour of the development of "compassionate communities" that aim to strengthen and broaden this kind of social support (42).
The shift towards more "inner directed" values and sources may be explained from a developmental perspective: later stages of life have been shown to lead people towards deeper introspection and integration (43)(44)(45). Terror management theory has also highlighted the importance of mortality awareness for the response shift phenomenon (46,47). While being confronted with death and finitude may induce fear and anxiety, experiential reality of impending death may also elicit a so-called "mortality-induced growth" associated with a transition from extrinsically oriented goals to intrinsic ones, such as appreciation for life, MIL, and spirituality.

The association between MIL and QOL
The finding that MIL represents a significant predictor of QOL, explaining up to 22% of the QOL variance, highlights the importance of the existential dimension for QOL in both populations studied, and is consistent with previous findings (6,21). While the association between QOL and sociodemographic variables has been more frequently assessed in the general population (48)(49)(50), the majority of studies looking at the association of the existential dimension to QOL were realized in the oncology and palliative care settings (5,7,9,51).
Interestingly, the part of explained variance increased in the palliative care patients when considering the life areas contributing to MIL (from 13% to 22%), more so than in the general population (from 13% to 15%). Areas mentioned by patients refer to both intrinsic ("home garden", "art-culture") and extrinsic ("partnership", "social commitment") domains. Viktor Frankl, one of the pioneers of existential psychotherapy, underscored the necessity of considering MIL from a personal perspective by taking into account the concrete manifestations of MIL experienced through creativity and inner attitudes towards traumatic events (18). Our results confirm the necessity to focus on the essential life domains of patients in the end of life context. These domains may be viewed as an adapted set of areas relevant to the patients' identity and sense of coherence, allowing them not only to anchor themselves in the reality, but also to identify new purposes and directions in which to invest for the remaining time. This approach can also be used as a "door opener" in order to address the existential dimension with palliative care patients (26).

Limitations
This study has several limitations. First, the methodology used to assess MIL with the SMILE questionnaire was different in the two populations (face-to-face interviews vs. telephone survey), which may account for some divergences in the responses. Second, the categories associated with the areas were assigned "a posteriori", which implies a degree of subjectivity by the investigators.
Third, although the use of a single-item scale for the assessment of QOL has been validated in the clinical context (52,53) and appears justified when considering the subjective approach to QOL advocated by the WHO, such an evaluation does not allow an in-depth assessment of QOL. Finally, the cross-sectional design of this study does not allow for a causal interpretation of the relationship between MIL and QOL.

Conclusions
In conclusion, our data reinforce the notion of the importance of MIL for QOL in both clinical and nonclinical settings. From a clinical perspective, it highlights the importance of considering closely the concrete life areas contributing to MIL in every single patient, since they play an important role not only for the patients' MIL, but also for their QOL. were obtained from all participants. Regarding specifically the survey with the representative sample of the Swiss population, the Ethical Committee did not ask for a submission since the participants were not patients and the data collection was anonymised. Nevertheless, all participants were informed that this survey was mandated by the University hospital of Lausanne in Switzerland and concerned perceived meaning in life, quality of life and general health status.

Competing interests
The authors declare that they have no competing interests.

Acknowledgements
We would like to sincerely thank all the participants of this study for having given their time and their energy for this research.

Availability of data and materials
The datasets used and analysed during the current study are available from the corresponding author on reasonable request.

Authors' contributions
MB was involved in the conception and the design of the study, the acquisition and the interpretation of the data, and the writing of the submitted version. AB was involved in the analysis and the interpretation of the data and the writing of the submitted version. FS was involved in the conception and the design of the study, the acquisition of the data and the revision of the submitted version. CG was involved in the conception and the design of the study, the acquisition of the data and the   Regression models are controlled for sociodemographic variables: age, gender, marital status, education; for the backward regression, only significant factors are displayed; CI: Confidence Interval