Prevalence and correlates of depression among chronic kidney disease patients in Taiwan

Chronic kidney disease (CKD) is becoming a major public health concern. The worldwide prevalence of end-stage renal disease (ESRD) is expected to continue to rise at an annual rate of 7% and exceed 2 million by 2010, which will cost about 1.1 trillion dollars in medical expenditures [1]. Recently, based on a report by the United States Renal Data System published in 2007, Taiwan had the highest incidence and prevalence rate of ESRD patients globally, with 415 and 2288 per million populations, respectively [2]. The soaring number of patients with renal disease resulted in a heavy economic burden to the healthcare system. According to a report by the Taiwan National Department of Health published in 2009, the number of ESRD patients only accounted for 0.2% of all beneficiaries, but consumed 32.8 billion NTD (New Taiwan Dollar), which is approximately 7.1% of the entire Medicare budget, and surpasses the medical expenditures on cancer (18.3 billion NTD) [3].

CKD not only causes enormous economic losses, but also triggers major challenges in regards to health. Wen and colleague [4] found that CKD patients had an 83% higher rate of all-cause mortality and were twice as likely to die from cardiovascular disease. Due to the irreversible nature and poorer prognostic outcomes, psychiatric disorders, in particular depression, are frequently common among patients with renal disease [5‐7]. One study found that ESRD patients have a nearly 4-fold higher risk for depression than the general population [8]. One cause of concern was that depression not only elevated the length of hospitalization by 30% [9], but also more than doubled the likelihood of mortality in ESRD patients with depression compared to those with ESRD only [8]. However, in contrast to available data on ESRD, there is a limited amount of information regarding depression among patients with earlier stages of CKD. Recently, a study demonstrated that depression in CKD patients, who were not receiving dialysis treatment, was linked to a 86% higher risk of adverse events including death, early dialysis initiation or hospitalization risk [10], suggesting that depression is a matter of great concern during the routine care of CKD patients.

Although some studies on depression and its contributing factors among CKD patients have been conducted, the majority of the studies were performed in Western countries [10‐12]. Influenced by the Asian conservative culture, Chinese often regard depression as a taboo and are, thus, highly reluctant to mention this openly to others [13]. Thus, a review of the literature indicates that most reports on Taiwanese CKD patients have focused on the effects of medical treatment [14], self-care behaviours [15], and possible pathogenic factors [16]. Conversely, research findings on depression among Chinese CKD patients are scarce. This study aimed to examine the prevalence of depression and related correlates among Taiwanese CKD patients, with the hope that findings may suggest appropriate psychological intervention strategies for Asian CKD patients.

To the best of our knowledge, there are no studies that have reported the prevalence of depression, along with its influencing factors, among Chinese CKD patients. This study found that the crude and age-adjusted prevalence of depression were 22.6% and 20.6%, respectively, revealing that one out of five CKD patients met the criteria for depressive disorders. This finding corraborates the 20% to 26% prevalence of depression found among renal disease patients who had received dialysis treatment [10‐12]. It was inferred that CKD gradually induces fatigue, nausea, and loss of energy [22]. Furthermore, the changes in body image and inconvenience resulting from subsequent dialysis treatment may also heighten the level of depression in CKD patients [23]. Despite the fact that depression is increasingly prevalent among CKD patients, its detection and management are still not recognized in routine care [12]. Most importantly, a large number of Asian individuals view depression as a taboo and do not openly seek regular psychotherapy [24]. Therefore, healthcare providers must be cognizant of the existence of depression among CKD patients and inform them by standard care procedures to avoid possible embarrassment and discomfort when implementing early screening to identify and refer high risk cases [11, 25].

With respect to the correlates of depression, the results of the multiple logistic analysis indicated that patients’ sex, age and marital status were not associated with depression among CKD patients, echoing previous findings [11, 12, 21]. The failure to observe any link between patients’ age and depression may also be partly due to the restricted age range of the participants and their older age (M = 64.5 years). Additionally, we found that living alone was not associated with an increased risk of depression. Despite the lack of comparable studies, the relationship between one’s living status and depression approached borderline significance. Further studies are still warranted to clarify the relationship between them. In regards to religious beliefs, patients with no religious beliefs were 2.5 times more likely to experience depression than those who reported having religious beliefs. It is possible that patients with religious beliefs had the opportunity to associate with other people and this experience may enhance psychological support, provide comfort through religious and spiritual counseling, and help relieve psychological pressures [26]. Our findings, however, differed from those reported by Chen et al. [21]. This inconsistency may be associated with the differences in the study participants (i.e. all subjects were hemodialysis patients in Chen et al. study) and statistical analysis methods (Chen et al. relied solely on univariate analysis). Using only univariate analysis to assess the relationship between religion and depression, instead of adopting a more comprehensive multivariate model that controls for potentially intervening covariates, may not accurately reflect the relationship between religion and depression.

This study also revealed that those with sleep disorders were three times more likely to have depression than those with no sleep problems. Despite the paucity of findings on the relationships between sleep disorders and depression among CKD patients, this finding is consistent with the theory that insomnia was related to the risk of depression in the general population [27]. From a neurobiological perspective, the arousal system of individuals who experience insomnia was more active than in those of the general population. This phenomenon would cause altered corticothalamic activities, such as higher concentrations of adrenocorticotropin (ACTH) and cortisol, which might further predispose them to develop psychiatric disorders [27, 28]. Therefore, it could be suggested that periodic assessment of sleep disorders in CKD patients could be of utmost clinical importance to reduce the risk of depression.

Individuals who did not exercise had higher odds of developing depression than those who did, echoing a previous study [11]. Two reasons may account for this result. First, those who exercise regularly are able to strengthen their social network, thereby having more resources with which to face the impact of the disease. Second, a former study had reported that exercise could increase the concentration of certain monoamine neurotransmitters, such as serotonin, norepinephrine and dopamine [29], which may stimulate the brain to produce endorphins that help the individual feel happier and more relaxed [30]. However, Johansen et al. [31] found that over 60% of healthcare providers do not assess the exercise patterns or recommend appropriate exercise programs for patients with renal disease. Healthcare providers should design a personalized exercise program based on the patient’s level of physical functioning, including activities such as walking, tai-chi, yoga, or swimming, to delay the deterioration of renal function and further relieve stress associated with the disease [32]. Furthermore, these exercises were also recommended to be integrated into the home-based or dialysis-based training programs which may be beneficial in increasing the motivation levels of individuals with CKD to engage in exercise, thus decreasing the risk of depression [33].

The findings of our study also show that the more advanced the stage of kidney disease, the more likely the patient is to demonstrate a depressive mood. This finding differs from a report of Hedayati et al. [12]. It could be speculated that these conflicting findings are due to differences in the measurement tools and classifications used. For example, Hedayati et al. [12] used the Mini International Neuropsychiatric Interview Tool to examine the prevalence of depressive episodes, which was distinct from our scale (TDQ). Furthermore, the study by Hedayati et al. classified CKD by four stages (from stage II to stage V), which was also different from the classification system used in our study. Nevertheless, as it relates to disease stage, patients with more advanced stages of kidney disease typically experience a large number of symptoms [6]. The dread associated with entering dialysis treatment and the anxiety over one’s changing health status may further aggravate depression [34]. Therefore, it is imperative for healthcare providers to periodically evaluate the emotional status of CKD patients with more advanced stages (i.e. stage IV or above).

The results of this study should be interpreted with the following limitations in mind. First, the study subjects were recruited from a single hospital, which may limit the generalizability of the findings and, therefore, these findings cannot represent the depressive symptoms of all Chinese CKD patients, and certainly not of non-Chinese populations. This limitation, however, is not unique to our study. By their very nature, most studies are limited by such factors as subjects’ ethnicity, geographical location, nationality and the nature of the medical data available (e.g., levels of severity, functionality, symptomatology, duration of condition). Future studies should be conducted in a variety of regions of the country to examine if the findings are replicated within different demographic and geographic groups. Nonetheless, we calculated a required sample size analysis to ensure statistical power before embarking on the study, and thus the sample size used in this study may be considered satisfactory for exploring the factors associated with depression in CKD patients. Second, since this study used a cross-sectional design, we cannot infer causality from our findings. A longitudinal research design is needed to examine any causal relationships among the factors assessed in this study, such as pro-inflammatory cytokines. Third, the self-reported depressive symptoms yielded by the TDQ may differ from those observed by a trained physician, so the present findings should be interpreted with caution. Fourth, the sleep disturbance was only examined with a single-item question and therefore its psychometric characteristic may be suspect and, accordingly, must be interpreted cautiously. Despite these methodological concerns, to our knowledge, this was the first study to review the epidemiology of depression among Chinese CKD patients who were not treated by dialysis, a fact which can be useful in developing an early therapeutic regimen for Asian CKD patients.

Modern medical technology can effectively extend the survival rate of patients with chronic diseases. However, the physical and mental distress that results from disease symptoms and their treatment may induce negative mood in the patient. In the present study, we found that the crude and age-standardized prevalence of depression among CKD patients were 22.6% and 20.6%, respectively. Patients with no religious beliefs, who did not regularly exercise, who had sleep disorders, and who were diagnosed with CKD stage IVor above, appeared to have a higher risk of developing depression. Healthcare providers should consider these findings as a reference for designing a standard rehabilitation program for CKD patients. Ensuring that mental health services are available to patients with CKD may be important first step to help them better psychologically adapt to their disease and possibly as important as improving the survival rate of patients with this chronic and life threatening disease.