Introduction

Chronic kidney disease (CKD) is an overall term that describes a wide range of disorders that affects the structure and function of the kidney [1], which is present for more than three months [2], [3]. At its worst phase, CKD can progress into end-stage renal disease. It is a major growing health issue in developed and developing countries worldwide [4], including Malaysia [3]. The prevalence in West Malaysia itself was found to be 9%, which is similar to what was reported in other Asian countries [5]. Therefore, it is crucial to study the effects of CKD as it is associated with increased hospitalisation, cardiovascular disease and mortality [6], [7], [8], [9], [10] that would significantly cause human, economic and social burdens on the nation’s health care system [3], [11]. Consequently, much research has been done in an attempt to understand the factors that influence the condition and its progression in CKD patients.

CKD not only compromises the physical health of patients but it also affects their psychological health, daily functioning, general wellbeing and social functioning, which are determinants of the patient’s quality of life [12], [13]. The World Health Organization (WHO) defined quality of life as how one perceived their position in life in taking into consideration their culture and value systems as well as its relation to their goals, expectations, standards and concerns [14]. Health-related quality of life (HRQoL) is the kind of quality of life that is impacted by health-related issues, and it can provide crucial information concerning how the patient is coping with their CKD condition [15]. Generally, CKD has a negative effect on sufferers’ HRQoL [16]. HRQoL was compromised even in the early stages of CKD [15], [17], [18]. Poorer HRQoL is also associated with higher risk of developing end-stage kidney disease, which then predicts mortality and hospitalization [8], [9], [19], [20].

Research has found some links between personality traits and certain health related outcomes [6], [21], [22], [23]. The most common personality model explored has been the Big Five personality traits, which encompassed openness, conscientiousness, extraversion, agreeableness, and neuroticism. In general, openness, extraversion and conscientiousness traits have been associated with perceived better health [21]. Specifically, it has been found that neuroticism is associated with increased risk for physical disorders including kidney disease [6], [22]. Neuroticism was also related to perceived poorer health [6], [21]. On the other hand, conscientiousness was related to better adherence to prescribed medication [6], [23]. Therefore, certain personality traits have been associated with behaviours that will lead to better HRQoL.

Social support has been found to alleviate the negative impacts of CKD on patients’ HRQoL. Social support is the complex network of how a person gets and give information and aid, as well as how they meet their emotional needs [24]. This can be acquired from family, friends, and other social networks available to the individual [21], [22]. Social support has been found to be associated with better survival, lower depression and higher compliance to medication [24], [25]. In addition, it has also been related to better immune function as well [24]. Poorer social support has been found with increased mortality [26], decreased HRQoL [26] and increased hospitalization [27].

HRQoL is significantly compromised with the presence of CKD, and it has been found that personality and social support can influence HRQoL outcomes in patients suffering from CKD. These psychosocial factors are important, as it could provide crucial information on prolonging CKD patients’ survival, as well as maintaining their quality of life. As such, this study aims to explore the relative influence of both personality traits and social support on HRQoL in patients suffering from CKD, specifically within the Malaysian context.

Methods

Results

Table 1 shows the demographic profile of the current study. Participants consisted of 108 males (54.0%) and 92 females (46.0%) with the mean age of 59.3 years (SD 14.5). Most of the participants were of Malay ethnicity (66.5%), followed by Chinese (26.5%), Indian (6.5%) and others (0.5%). Out of the 200 participants, the majority of participants were currently in Stage 3 in their CKD progression. Diabetes was reportedly the cause of CKD for most participants.

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Table 1. Patient characteristics with their frequency and percentage.

https://doi.org/10.1371/journal.pone.0129015.t001

The correlations between age, GFR, the Big Five personality traits, social support and the physical (PCS) and mental (MCS) components of the HRQoL are displayed in Table 2 along with the means and standard deviations. Pearson’s correlation was employed to explore the relationships between these variables. Older patients tended to rate poorer physical HRQoL. Higher GFR scores (earlier stages of CKD) were associated with better perceived physical and mental HRQoL. Patients reporting being more open to new experiences and more extraverted reported better physical HRQoL. Patients who perceive having higher affectionate social support also reported better physical HRQoL. Patients who reported being open, conscientious and extraverted correspondingly reported better mental HRQoL. Patients high in neuroticism tended to respond with poorer mental HRQoL. None of the social support components correlated significantly with neither physical nor mental HRQoL. Better physical HRQoL was associated with better mental HRQoL.

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Table 2. Means, standard deviation (SD), and Pearson correlations (r) of the age, GFR, components of Big Five traits, social support and physical (PCS) and mental (MCS) health-related quality of life.

https://doi.org/10.1371/journal.pone.0129015.t002

Hierarchical multiple regression analysis was then performed to investigate how much of the variance in physical HRQoL could be explained by personality and social support after controlling for age and GFR. The hierarchical model for physical HRQoL is summarised in Table 3. For physical HRQoL, age and GFR were entered in the first block, followed by openness, extraversion and affectionate social support in the second block. At Step 1, age and GFR accounted for 13% of the variance in physical HRQoL, Fch (2, 197) = 14.21, p < .001. Both age and GFR were significantly associated with physical HRQoL, such that being older was associated with poorer physical HRQoL, β = -.14, p = .043, age uniquely explained 2% of the variance. GFR also associated with HRQoL, such that earlier stages of CKD was associated with better physical HRQoL, β = .29, p < .001, GFR uniquely explained 8% of the variance. At Step 2, the addition of openness, extraversion and affectionate social support explained 6% of the variance over and above age and GFR, Fch (3, 194) = 4.84, p = .003. Both extraversion and affectionate social support were significantly associated with physical HRQoL. Being extraverted was associated with better physical HRQoL, β = .15, p = .035, extraversion uniquely explained 2% of the variance. Perceiving more affectionate social support was associated with better physical HRQoL, β = .15, p = .021, affectionate social support uniquely explained an additional 2% of the variance. Openness was not significantly associated with HRQoL. Overall, at Step 2, age, GFR, openness, extraversion and affectionate social support significantly accounted for 19% of the variance in physical HRQoL, F (5, 194) = 8.92, p < .001.

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Table 3. Hierarchical regression model of physical health-related quality of life.

https://doi.org/10.1371/journal.pone.0129015.t003

Another hierarchical multiple regression analysis was performed to investigate how much of the variance in mental HRQoL could be explained by personality after controlling for GFR. The model for mental HRQoL was summarized in Table 4. In terms of mental HRQoL, GFR were entered in the first block, followed by openness, conscientiousness, extraversion and neuroticism. At Step 1, GFR accounted for 5% of the variance in mental HRQoL, Fch (1, 198) = 9.81, p = .002. GFR was significantly associated with mental HRQoL, such that earlier stages of CKD was associated with better mental HRQoL, β = .22, p = .002, GFR uniquely explained 5% of the variance. At Step 2, the addition of openness, conscientiousness, extraversion and neuroticism explained 19% of the variance over and above GFR, Fch (4, 194) = 11.98, p < .001. Only neuroticism was significantly associated with mental HRQoL, such that higher neuroticism was associated with poorer mental HRQoL, β = -.36, p < .001, neuroticism uniquely explained 9% of the variance in mental HRQoL. Overall, at Step 2, GFR, openness, conscientiousness, extraversion and neuroticism significantly accounted for 24% of the variance in mental HRQoL, F (5, 194) = 11.98, p < .001.

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Table 4. Hierarchical regression model of mental health-related quality of life.

https://doi.org/10.1371/journal.pone.0129015.t004

Discussion

This study was conducted to explore the contributions of the Big Five personality traits and social support to HRQoL in patients with CKD. The findings revealed that both age and the progression of CKD were associated with HRQoL, such that older age and later stages of CKD were associated with poorer HRQoL. Two of the Big 5 personality traits, namely extraversion and neuroticism, were also associated with HRQoL. In relation to social support, we found that only affectionate social support had an associated with physical HRQoL.

The inverse relation between age and HRQoL was found in the current study, which was consistent with findings of previous studies [17], [18], [38]. However, it should not be interpreted that age causes poorer HRQoL per se. With the progression of age, the period of having CKD is also prolonged. With a longer duration of having the disease, there might be an accumulation of various other factors that could influence the progression of the disease and the wellbeing of the patient. Therefore, HRQoL is usually found to decline over time [38].

Various studies demonstrated the association between the progression of CKD and HRQoL [15], [38]. Similarly, our results also found that HRQoL is compromised with the decreased functioning of kidneys due to CKD, as measured by GFR. This also tied in with the previous point. Over time, if the patient does not seek appropriate treatment, CKD could progress into more advance stages of the disease. With increased deterioration of kidney function, various health and lifestyle changes have to be practiced in order to maintain functions of the kidney. In addition, it was argued that the knowledge of having the disease or being labeled could also influence HRQoL [17]. This was found in patients who were also having hypertension on top of CKD who reported poorer HRQoL despite hypertension being asymptomatic [17]. However, there are studies that found no association between changes in HRQoL and changes in GFR [11] [18], [39]. Therefore, it could be suggested that the association between HRQoL and GFR may also be influenced by other factors such as anemia, nutritional status, and albumin among others.

Extraversion was found to be significantly associated with physical HRQoL. This was consistent with findings of previous studies. Higher levels of extraversion were related to better health outcomes [40], [41], [42]. In addition, a study done on patients who recently had a kidney transplant found that higher extraversion was associated with better mental HRQoL [41]. Extraverted people tended to engage in more active coping mechanisms, and they preferred external stimulation [41]. Therefore, it could be argued that they may be easily distracted away from their disabilities.

Neuroticism was also found to significantly associate with poorer mental HRQoL. This finding supported studies finding an inverse relationship between neuroticism and perceived health [21], [40], [41]. These studies found that people with lower neuroticism traits tended to reported better health outcomes [40], better health perception [21], [42], [43], as well as both physical and mental HRQoL [16]. One reason for this could be that people with higher neuroticism traits tend to be more negative in the way they perceive the world. Therefore, they were likely to be hypervigilant towards negative stimuli that they encounter. It is no surprise then, that patients with higher trait neuroticism would be more preoccupied with their health symptoms, and complain about it more and consequently perceived poorer HRQoL [16], [41]. Moreover, healthy people without any medical problems with type of personality also tended to perceive poorer health [21].

There was no association found between conscientiousness, agreeableness and openness and HRQoL. This could be due to the fact that these personality factors do not influence HRQoL directly, but they are associated with other behaviours that may predict better health. This may be true for other personality traits, except for openness, whereby it was found to be not a correlate of self-rated health [40]. Higher levels of agreeableness, conscientiousness and extraversion were found to predict better self-rated health [40]. Conscientiousness was better associated with treatment adherence [42], [44] and therefore might have lead to improved HRQoL. These behaviors and outcomes might not necessarily translate into quality of life, as they might not be living their life as how they would like, and therefore perceived their quality of life to be significantly affected by their illnesses. This could suggest that how patients view their illness may play a bigger role in predicting HRQoL rather than patients’ personality traits.

Contradictory to the literature [26], [27], social support was not a significant predictor of HRQoL, except for affectionate social support, which was the expression of love and affection, was found to significantly predict physical HRQoL. Consistent with a recent study done on breast cancer patients, social support, specifically emotional and informational support as well as affectionate and positive social interaction support were more important in improving quality of life, rather than tangible social support [45]. Patients felt that emotionally focused support was better in helping them cope with high distressing events. However, not all social supports were perceived to be helpful [46], [47]. Certain behaviours that were thought to be supportive may be perceived as unhelpful to patients, such as overreactions, unhelpful advice, and tendency to treat the patient as an invalid among others [48]. Being overly concerned about the patient might also make them feel different and it would highlight their disability and sickness [49].

Conclusion

Despite the limitations noted, the current study added to existing literature that investigated psychological factors and quality of life in CKD. Moreover, this study was among the first that explored personality traits predicting HRQoL in CKD within Malaysian context. Consistent with previous findings, we found that certain personality traits were significantly associated with HRQoL such neuroticism as well extraversion. In addition, affectionate social support was also found to be significantly associated HRQoL These were all important factors to take into account when designing intervention for patients with CKD in order improve their wellbeing and health outcomes. Future studies should look into more qualitative exploration, especially social support so to be able to explore what kind of social support patients feel to be useful and supportive in aiding their treatment effects, and also to see if certain personality traits might perceive different types of social support to be helpful versus non-helpful and what kind of effect will that have on quality of life.

Supporting Information

Acknowledgments

We would like to thank all the patients with CKD who agreed to participate in our study from the Nephrology Clinic at the National University of Malaysia Medical Centre (HUKM). This study is funded by Grant Code no.: GGPM-2012-100.