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| Year : 2012 | Volume
: 23
| Issue : 3 | Page : 493-499 |
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| Poor quality of life is associated with increased mortality in maintenance hemodialysis patients: A prospective cohort study |
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Ibrahim Guney1, Huseyin Atalay2, Yalcin Solak2, Lutfullah Altintepe1, H Zeki Tonbul2, Suleyman Turk2
1 Department of Nephrology, Konya Research and Training Hospital, Konya, Turkey
2 Department of Nephrology, Meram School of Medicine, Selcuk University, Konya, Turkey
Click here for correspondence address and email
| Date of Web Publication | 7-May-2012 |
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 Abstract | | |
Despite all developments in hemodialysis (HD), the mortality rate is still apparently higher than that in the general population, and worse health-related quality of life (HRQOL) is associated with increased mortality. We prospectively investigated the mortality status of HD patients during a five-year period and the association between mortality, HRQOL, laboratory parameters and clinical and sociodemographic characteristics at baseline. At the end of the five years, 293 patients out of 420 patients were still on HD treatment and 127 patients died. Those who died had a higher mean age, lower mean values of serum creatinine and albumin, higher prevalence of diabetes mellitus, received more HD twice weekly for less than 4 h in almost all HD sessions and had lower HRQOL than the survivors. We conclude that age, comorbidity, HD sessions lasting less than 4 h, malnutrition [hypoalbuminemia, low body mass index (BMI)] and lower physical component scores of SF-36 survey (PCS) were associated with higher risk of death in the HD population.
How to cite this article:
Guney I, Atalay H, Solak Y, Altintepe L, Tonbul H Z, Turk S. Poor quality of life is associated with increased mortality in maintenance hemodialysis patients: A prospective cohort study. Saudi J Kidney Dis Transpl 2012;23:493-9 |
How to cite this URL:
Guney I, Atalay H, Solak Y, Altintepe L, Tonbul H Z, Turk S. Poor quality of life is associated with increased mortality in maintenance hemodialysis patients: A prospective cohort study. Saudi J Kidney Dis Transpl [serial online] 2012 [cited 2013 May 25];23:493-9. Available from: http://www.sjkdt.org/text.asp?2012/23/3/493/95764 |
| Introduction | |  |
Despite technical developments in hemodialysis (HD), the mortality rate is still inacceptablely higher than that in the general population. It was reported that some demographic factors such as age, male gender and white race, [1] some disease states such as diabetes mellitus (DM) and cardiovascular disease (CVD) and certain laboratory parameters such as serum albumin and creatinine [2],[3] were related to increased mortality of HD patients. Besides, in a number of studies, it was shown that worse health-related quality of life (HRQOL) was also associated with increased mortality. [4],[5],[6],[7] The DOPPS study (The Dialysis Outcomes and Practice Patterns Study), which was conducted in 2003, found that one year mortality rates of HD patients in Japan, European Countries and USA were 6.6%, 15.6% and 21.7%, respectively. [8]
We aim from our study to evaluate the mortality status of HD patients during a five year period and the association between mortality and HRQOL, certain laboratory parameters and clinical and sociodemographic characteristics at baseline. To the best of our knowledge, this study is among the few studies to investigate the relation between HRQOL and mortality in a prospective design.
| Materials and Methods | | |
This is a prospective cohort study. We first evaluated the relationship between clinical, sociodemographic characteristics, laboratory data and HRQOL in 511 patients from ten HD centers in Konya, Turkey. [9] We re-evaluated the mortality status and factors affecting mortality during a five-year period in 420 maintenance HD patients. We excluded patients who underwent renal transplantation (42 patients, 8.2%), shifted to peritoneal dialysis (12 patients, 2.3%), moved outside the city (10 patients, 2%) and lost to follow-up (27 patients, 5.3%).
Social characteristics, i.e. education status, employment status and life styles, were recorded through interviews with the patients. Other features of the patients (age, gender, HD durations, etc.) and their laboratory parameters were collected from the HD center records. In addition, blood pressures (BP) of the patients for the last three HD sessions were obtained from medical records of the respective HD centers.
Davies comorbidity score was calculated for each patient. malignancy, ischemic heart disease, peripheral vascular disease, left ventricular dysfunction, DM, systemic collagen vascular diseases, chronic obstructive pulmonary disease that is severe enough to adversely affects life, cirrhosis and psychotic conditions were taken into account as comorbid conditions. The score was graded as follows; grade 0: no comorbid disease, grade 1: one or two comorbid conditions present, grade 2: three or more comorbid conditions present. [10]
In order to evaluate HRQOL of the patients, a short form of the Medical Outcome Study (SF-36) [11] , which had been adapted to the Turkish population, was used. [12] The form consists of 36 items, which are assigned to eight dimensions, namely functional capacity (tenitems), physical role functioning (four items), bodily pain (two items), general health perceptions (five items), vitality (four items), social role functioning (two items), emotional role functioning (three items) and mental health (five items). Each scale is scored with a range from 0 to 100. The first four items constitute a physical component scale (PCS) and the last four items constitute a mental component scale (MCS). [13] It was shown that these two summary scales adequately represent values of their individual scale components with 80% and 85% variability. [14] The higher the scale, the better is the QOL. This scale has been commonly used and validated in patients with endstage renal disease (ESRD). [15]
| Statistical Analysis | | |
The analysis was performed using SPSS 15.0 program (Statistical Package for the Social Sciences Inc., Chicago, IL, USA). Student's t-test was used to compare the means of normally distributed variables and the Mann-Whitney U test was used for variables that were not normally distributed. Differences among categorical variables were analyzed using the chi-square test. Survival rate was calculated according to the Kaplan-Merier method. The Cox regression was used to identify the risk factors that could independently influence patient survival on HD. The analyses were adjusted for patients' age, comorbidity index, durations of HD sessions, number of HD sessions per week, body mass index (BMI), Kt/V, PCS, MCS, serum albumin and hemoglobin (Hb) levels. A P-value <0.05 was considered statistically significant.
| Results | | |
The study patients had an average age of 48.7 ± 15.4 years, and included 228 (54.3%) men and192 (45.7%) women. The most common etiology of primary kidney disease in the study patients was DM (15%). Chronic glomerulonephritis and urologic causes were responsible for 14.5% and 14.0%, respectively. Fifteen patients were dialyzed via permanent tunneled central venous catheters (CVC). Estimation of patients survival by Kaplan-Meier analysis was 91.2%, 80.0%, and 69.8% at one, three and five years, respectively. We found that the most common cause of death was CVD (60 patients, 47.2%), followed by infection (18 patients, 14.2%) and cerebrovascular accident (CVA) (six patients, 4.7%).
We did not find a significant difference between the surviving and non-surviving patients in terms of sex, HD duration, life style, education and employment status. However, the non-surviving patients were older than the survivors (57.5 ± 12.8, 44.8 ± 14.9, respectively, P < 0.001). Among the non-surviving patients, DM was observed more frequently as primary kidney disease (33 of non-surviving patients, 26.0%; 31 of surviving patients, 10.6%, P = 0.004) [Table 1]. | Table 1: The initial sociodemographic characteristics of the surviving and non-surviving study patients.
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When the non-surviving and the surviving patients were compared in terms of their cigarette smoking, systolic and diastolic BP prior to dialysis, BMI, Hb, serum urea, calcium (Ca), phosphorus (P), Ca x P product and Kt/V, there was no statistically significant differences between these groups. However, the comorbidity index was higher in the non-surviving than in the surviving patients (P <0.001). Moreover, the percentage of twice-a-week HD was higher in non-surviving than in surviving patients (14.2% and 6.8%, respectively, P = 0.025), and shorter HD sessions (less than 4 h) were observed more frequently in the non-surviving than in the surviving patients (11% and 5.1%, respectively, P = 0.036).
Laboratory parameters including serum albumin and creatinine were significantly lower in the non-surviving (3.98 ± 0.53 and 7.9 ± 2.88, respectively) than in the surviving patients (4.15 ± 0.50 and 8.99 ± 2.99, respectively, P = 0.002 and 0.001, respectively) [Table 2]. | Table 2: The initial clinical and laboratory findings of the surviving and non-surviving study patients.
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When the surviving and non-surviving patients were compared in terms of the HRQOL scores, they were significantly lower in the non-surviving patients including functional capacity (P <0.001), physical role functioning (P = 0.026), vitality (P = 0.005), mental health (P = 0.033), total SF-36 score (P = 0.002), and PCS (P < 0.001) [Table 3].  | Table 3: The initial QOL scores of the surviving and non-surviving patients.
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The parameters that affected mortality among the initial demographic, clinical and laboratory findings were re-evaluated by using the Cox regression [Table 4]. Compared with the reference group (25-34 years), the relative risk (RR) for death increased significantly with ageing, and the highest RR was found in the ≥65 years age group (RR 7.37; P <0.001). When the HD session duration was less than 4 h, the RR of death increased by 2.92-times (P = 0.001). It was also found that the mortality risk increased by 6% with every 1 kg/m 2 decrease in BMI (P = 0.029), and the mortality risk increased nearly two-times with every 1 g/dL decrease in the albumin level (RR = 1.92; P = 0.001). Moreover, the presence of comorbidity increased the mortality risk by 1.76-times (P = 0.008). In addition, every 1 point decrease in PCS also increased the mortality risk by 2% (P = 0.018).
| Discussion | | |
The results of this study showed that HRQOL scores, serum albumin and BMI values were lower, and shorter dialysis sessions and twice-a-week sessions were more frequent in non-surviving patients compared with surviving patients.
Various studies reported that CVD is still the most common cause of mortality, [16],[17],[18],[19],[20] followed by CVA and infections in HD patients. In the 2005 registry report of the Turkish Society of Nephrology, it was declared that 1058 (10.7%) patients in the maintenance HD program died, and the most frequent causes of death were CVD (42.0%), infection (10.6%), malignancy (9.3%) and CVA (8.7%) (20). In this study, the most frequent cause of death was CVD (47.2%), and the second most frequent cause was infection (14.2%).
In previously studies, it was reported that the risk of mortality increased with advancing age. [17],[18],[22],[23],[24] In the DOPPS study, the relative risk of death increased by 10% with every 10 years increase in age. [21] Our findings also showed that the non-surviving patients were older (P<0.001), and that the RR of death also increased with age.
In the studies investigating mortality in HD patients, a reverse relationship was found between albumin and mortality risk. [4],[5],[6],[16],[25],[26],[27] Leavey et al. found that in the 3607 HD patients observed for five years, the RR for mortality decreased by 33% with every 1 g/dL increase in the albumin level. [25] Our results were comparable with this finding. This fact may illustrate the adverse impact of malnutrition on mortality risk of maintenance HD patients.
Pifer et al have found that in patients with the lowest BMI, the mortality risk was the highest. [26] Port et al examined the influence of urea reduction ratio (URR) and BMI on the patient survival in 45,967 HD patients, and they found that in every URR level the relative mortality risk was higher for patients with low BMIs. [28] Our findings were comparable to those found by Pfifer et al.
In the DOPPS study, all the comorbid diseases excluding hepatitis B and peptic ulcer were found to be related to increased risk of mortality. [23] In another study, the authors found that as the number of comorbidities increased, the RR for mortality increased as well. [17] Similar to these studies, in our study, the mortality risk was found to be higher in patients with comorbidities.
It is clearly seen in the aforementioned studies that many factors affecting the HRQOL (age [9],[29],[30] and hypoalbuminemia [9],[29],[31] , etc.) are indeed related to mortality risk. De Oreo et al. studied the risk of mortality in HD patients and concluded that only PCS was related to this risk, but it had no relation to MCS. [7] In contrast, Kalantar-Zadeh et al did not find a relationship between the mortality risk and PCS; however, they indicated a strong relationship between MCS and risk of mortality. In the same study, it was also found that with every 10-point decrease in the total SF-36 score, the risk of mortality increased by 2.07-times (P = 0.024). [6] Mapes et al reported that both PCS and MCS were related to the risk of mortality. When the sociodemographic variables in this study (life style, working and education status, age, sex and dialysis duration) were corrected, it was found that with every 10-point decrease in PCS, the risk of mortality increased by 25%, and it was also stated that with every 10-point decrease in MCS, the risk of mortality increased by 13%. [5] In another study, the HRQOL and the risk of mortality decreased by 2% with each 1 point increase in both PCS and MCS. [4]
Finally, we found that all the SF-36 scores in the surviving patients were higher than those in the non-surviving patients, including the changes in the functional capacity, physical role functioning, vitality, mental health, PCS domain score and total SF-36 scores.
This study has some limitations. We only measured the HRQOL twice during a five year follow-up; thus, we have no data regarding HRQOL and related factors between the start and the end of the study.
In conclusion, mortality rates are unacceptably high in the HD population, and mostly due to cardiovascular disease. Age is a major factor for increased risk of mortality. The compliance with dialysis sessions, the presence of comorbidity and the factors related to malnutrition (hypoalbuminemia and low BMI) also affect HRQOL and mortality in HD patients. Furthermore, poor HRQOL, especially its physical component, increased the risk of mortality. Modifying the factors that affect the risk of mortality and HRQOL in HD patients may result in a better quality of life and a longer span of life.
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Correspondence Address:
Yalcin Solak
Nephrology Department, Meram School of Medicine, Selcuk University, Konya
Turkey
[Table 1], [Table 2], [Table 3], [Table 4] |
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