Chronic kidney disease (CKD) is a disease comprising of a wide spectrum of different pathophysiological processes, which is associated with abnormal renal function and a gradual degeneration of the glomerular filtration rate (GFR). The National Kidney Foundation’s staging system divides the CKD patients in 5 stages according to GFR. Stage V is usually labelled as end stage renal disease (ESRD) [1] .

The worldwide incidence of ESRD is increasing at a rate of about 7% per annum, and the disease has been estimated to cost approximately 1.1 trillion dollars in medical expenditures worldwide [2] . The high incidence of chronic kidney disease in the Pakistani population is far from surprising, since the prevalence of diabetes and hypertension is very high for this population [3] .

Previous studies have reported an overall mortality rate, 83% higher for CDK patients than for the general po- pulation, and also found that cardiovascular disease was twice as common in CDK patients, compared to the healthy population. Due to the irreversible nature of this disease and the bleak prognoses associated with it, psychiatric disorders such as depression are commonly observed among CKD patients [4] -[6] . Depression may be triggered by a number of social, biologic, and psychological factors, and this has been reported to occur at any point during the progression of CKD [7] . Factors that affect the risk of depression include socioeconomic factors, and education status, the gender of the patient, and the presence/absence of symptoms such as disturbed liver function due to hepatitis, hypertension or hypoalbuminemia [8] .

Although depression is frequently observed among renal dialysis patients, active detection and management (in form of psychotherapy and/or pharmacotherapy) are usually not part of the routine care for these patients [9] . To date, very few data are available regarding the frequency of depression in CKD and dialysis patients in Pakistan, and hence, we aimed to explore this.

Out of a total of 315 patients enrolled in the study, 204 (64.76%) patients were in dialysis group and 111 (35.24%) were in pre-dialysis group. In the pre-dialysis group, 52 patients were male, with a mean age (±SD) of 56.37 years ± 17.07, and 59 were female, with a mean age (±SD) of 49.36 years ± 19.17. In the dialysis group, there were 106 males and 98 females, with a mean age (±SD) of 49.49 years ± 17.47 and 44.17 years ± 17.83, respectively (Table 1).

30.5% of all patients belonged to the low income group; 38.1% of patients belonged to middle income group; and 31.4% of patients belonged to the high income group (Table 2). In total, 117 (37.1%) patients had no formal education; 76 (24.1%) had less than, or equal to, eight years of school education; 57 (18.1%) had greater than eight years but less than, or equal to, ten years of education; 52 (16.5%) had greater than ten years education with a less than, or equal to, graduate level education; and 13 (4.1%) had a postgraduate level of school education.

In the dialysis group, depression was present in 171 (83.8%) patients, whereas 33 (16.2%) patients showed no signs of depression. In the pre-dialysis group, depression was present in 68 cases (61.3%; Table 3). In the low- income group, 80 patients (83.3%) were diagnosed with depression. For the middle-income group, this number was 87 (72.5%), and for the high-income group, 72 patients (72.7%) had depression, as shown in Table 4.

Depression was present in 80 (68.4%) patients with no formal education and in 61 (80.3%) of patients belonging to the middle or less education group. The middle to matric education group had 45 (78.9%) cases of depression, whereas the matric to graduation groups had 46 (88.5%) cases of depression. and the post graduation group had 7 (53.8%) cases (Table 5).

There is increasing evidence supporting a role for psychosocial factors such as depression, anxiety, and perceived social support, in the pathophysiology of various chronic diseases, including CKD, where depressive disorders have been found to be associated with an increased risk of mortality, and poor health-related quality of life [10] . We here used the Hamilton Depression Rating Scale to diagnose the different stages of depression. The Hamilton Depression Rating Scale is one of many ways to stage depression, and has recently been shown to be a

¹Low income was identified as <10,000 PKR per month; ²Middle income was identified as 10,000 - 25,000 PKR per month; ³High income was identified as >25,000 PKR per month.

¹Absent vs. present depression.

¹Low income was identified as <10,000 PKR per month; ²Middle income was identified as 10,000 - 25,000 PKR per month; ³High income was identified as >25,000 PKR per month; ⁴Absent vs. present depression.

¹Absent vs. present depression.

valid alternative to these other methods [11] .

Similar results to what we found in this study have recently been reported by Hung et al. (2011), who explored the relationship between depression and demographic, socio-economic and clinical variables in CKD patients [12] . In another study, Wuerth et al. (2003) screened chronic peritoneal dialysis (PD) patients from July 1997 to October 2002, using the Beck Depression Inventory questionnaire. Based on the Hamilton Depression Scale and Standard Diagnostic and Statistical Manual of Mental Disorders criteria, 87% (comparable to 83.8% in our study) of their patients were diagnosed as being clinically depressed [13] .

Watnick et al. (2003) showed that symptoms of depression were frequently observed at the early stages of dialysis treatment. However, they also noted that despite a high prevalence, treatment for the depression was rarely prescribed, even for patients described as having moderate-severe depression [14] .

In two studies consisting of 210 and 380 peritoneal dialysis patients, scores consistent with a possible diagnosis of clinical depression were observed in 42% and 49%, respectively. Out of the patients who agreed to further testing, 87% and 84%, respectively, were diagnosed with clinical depression based on standard psychiatric criteria [15] [16] .

Hedayatti et al. (2009) found in their study that 1 in 5 patients with CKD had experienced at least one major depressive episode, and that, for patient with late-stage CKD, there was an independent association between depression and poor survival outcome [17] . Hence, we suggest, as they also concluded, that, given the high prevalence of depression in CKD patients, routine screenings should be performed.

Lastly, another study also showed that depression correlated with a considerably increased risk of death in CKD patients [18] . However, during the course of our study, no patients died, and we were hence unable to draw any conclusions regarding the correlation between CKD, depression and patient survival.

In summary, we here examined 315 Pakistani patients with CKD for signs of depression, and for any associations between depression and education status and income. We found that the frequency of depression was signi- ficantly higher in the dialysis group and was significantly associated with education status, with patients with higher levels of education showing a lower frequency of depression (P < 0.05). No association was found between depression and income status in this study. We conclude that given the high prevalence of depression in CKD patients, screenings should be routinely performed in order to identify and treat depression in its early stages for these patients.