To assess the quality of life in patients with chronic kidney disease undergoing hemodialysis at a satellite clinic, comparing patients from a median low-income household with patients from median middle- and upper-income households: cross-sectional study

Background: Chronic kidney disease is a financial challenge for global public health due to rising costs, a poorer quality of life. Globally, there has been an increase in the number of diabetic, hypertensive and obese patients, with a tendency to rise as life expectancy increases. Objective: To assess the quality of life of patients with chronic kidney disease on hemodialysis at a satellite clinic in Recife, Northeast Brazil, and comparing low-income patients funded by the national healthcare system with middle- and higher-income patients funded by private health insurance. Methods: The Medical Outcomes Study Questionnaire Short Form 36 Health Survey (SF-36) was applied, together with a complementary interview with sociodemographic data for all patients at a conventional hemodialysis clinic. All patients were submitted to the same hemodialysis protocol, 4 hours and 10 minutes, high flow biocompatible membranes with high mass transfer coefficient and an adequacy of Kt/V ≥1.2. Results: The poorest quality of life scores with the SF-36 were related to physical functioning and pain. The best scores were attributed to mental health, social functioning, general health and vitality with no differences between the household incomes. There was a positive association between education, role-emotional and physical functioning. Longer hemodialysis treatment times demonstrated a positive association with aspects of general health. Patients who had undergone hemodialysis between one and five years presented better quality of life scores with the SF-36. Conclusions: Hemodialysis treatment negatively influences the quality of life of

patients with chronic kidney disease. Education seems to help patients to better understand and accept treatment, by raising the scores of the physical functioning and role-physical. The first year of hemodialysis seems to exert a more negative influence on the quality of life. Among all patients, pain and physical aspects seem to be the critical points, regardless of social class or income.

Background
Chronic Kidney Disease (CKD) is a financial challenge for global public health [1] due to rising costs, a poorer quality of life and psychosocial factors [2]. Globally, there has been an increase in the number of diabetic, hypertensive and obese patients, with a tendency to rise as life expectancy increases [3].
However, with the continuing shortage of donor kidneys, most patients with endstage renal disease (ESRD) will need some form of dialysis during their lifetime. To date, no consensus has been reached as to whether peritoneal dialysis (PD) or hemodialysis (HD) offer patients a better chance of survival [4].
The difference between patient demand and the system's ability to absorb this population has put health systems at risk. According to the Brazilian Society of Nephrology (SBN), in 2000 there were 42.695 patients on HD and a prevalence of HD of 503 per million population (pmp). In 2017, there were an estimated 126.583 patients on HD, 80% [5] of whom were funded entirely by the Brazilian public health system (known as SUS), corresponding to a prevalence of 610 pmp. In some regions of Brazil there is a waiting period of up to four months for a vacancy at a hemodialysis satellite clinic. Available Brazilian data, although as yet unpublished, have demonstrated a total of 133.964 hemodialysis patients with a prevalence of 640 pmp, 92.3% maintained by SUS, with a kidney transplant waiting list of 29.545 [6].
For these previously mentioned reasons, conventional four-hour HD, three times a week, has become the fastest manner with which to reverse the critical symptoms of uremic syndrome and to quickly reverse the disparities regarding access to the public health system [7] [8]. However, while hemodialysis promotes life in the biological sense of the word, it also causes a further limiting factor, in that it imposes immobility onto human beings and the creation of a binomial man/artificial kidney dependence. Studies have demonstrated that this process of dependence may favor major depressive disorder, recurrent depressive disorder and suicide [9].
Depressive disorder is the most common psychiatric condition in patients with ESRD, with a prevalence of up to 100% in patients with CKD, varying according to the criteria used and the population studied. In Brazil, in two studies involving patients undergoing hemodialysis, the prevalence of major depressive disorder was 44.8% using the Beck Depression Inventory (BDI), and 7.8% with the 10-item version of the Center for Epidemiologic Studies Depression Scale (CES-D). A metaanalysis with hemodialysis patients presented increased depression and risk of psychiatric disorder-related hospitalization when compared with patients undergoing conservative treatment and post-renal transplantation [10] With the evolution of hemodialysis and peritoneal dialysis techniques, it has been possible to reduce mortality and increase the life span of these patients. However, a new concern has arisen amongst nephrologists. It is not simply enough to remain alive; it is necessary to offer these patients comfort and a better quality of life (QoL) [11].
Chronic kidney disease decreases both physical and professional functioning, imposes limits onto social relationships and causes problems related to mental health. There is no consensus in the medical literature on the items that should be taken into consideration when assessing the quality of life of patients with CKD. In order to understand the process between care and a sensation of well-being (positivity), several generic QoL questionnaires have been produced for patients with chronic diseases. Amongst these questionnaires, the international literature has demonstrated the effectiveness of the Medical Outcomes Study Questionnaire Short Form 36 Health Survey (SF-36) [12].
In Brazil, in 1997, Ciconelli et al. validated and adapted the SF-36 by applying the questionnaire to rheumatoid arthritis patients at the Universidade Federal de São Paulo, Brazil [13]. Since then, the questionnaire has been applied in order to assess patients with several chronic diseases, thereby providing an excellent performance and methodological correlation. The SF-36 was therefore selected due to the translation and linguistic adaptation into the Portuguese language, and because it is a generic quality of life assessment (QoL) tool, which is simple to understand and administer [13]. It is also sufficiently succinct and may therefore be applied in a hemodialysis setting where procedures are fast and there is a risk of accidents.
Another study in the metropolitan region of São Paulo, Brazil, used the same instrument to assess the QoL of patients with CKD in eight satellite dialysis clinics.
In this work, the SF36 was applied with no technical difficulties, analyzing a total of 80 patients, who were initiating HD treatment with an HD period of less than or equal to three months. A significant impairment was observed in the physical and emotional conditions of this population [14].

Objective
The objective of the present study was to assess the quality of life (QoL) of patients with CKD on HD at a satellite clinic in the city of Recife, Northeast Brazil, serving patients from the public sector (funded by SUS) with a median monthly household income of between US$ 78.00-281.00, and the private sector (funded by private health insurance) with a median monthly household income of between US$ 647.00-4.210,00.

Methods
This was a cross-sectional, descriptive, unicentric, individualized, randomized study of patients on conventional HD, in a satellite clinic that treated public sector, low-  [16]. Patients were excluded if they presented with Alzheimer's disease, neurodegenerative diseases, disorientation, organic difficulties or intellectual deficit that prevented applying the SF-36, and if they were hospitalized while the questionnaire was being applied. The SF-36 questionnaire was applied, and a complementary interview was conducted made up of questions regarding the type of health insurance (SUS or private health insurance), median household income, civil status, education and time spent on hemodialysis.
Location and period of the study The study was conducted at a healthcare satellite clinic, in Recife, the state capital of Pernambuco, in the Northeast of Brazil, in August 2011.

Calculating the SF-36 scores
The scores were calculated according to the international standardization of the Quality Metric SF Health Surveys [17].

Statistical analysis
Initially, we performed a descriptive analysis, and the homoscedasticity (Bartlett's test) and the normality of the continuous data were verified with the Kolmogorov-Smirnov test to assess normality. Categorical variables were expressed by their frequencies and percentages. The software used was Microsoft Excel 2013™ and the statistical treatment was performed with IBM SPSS Statistics Base V20™ for the results obtained and to present the means, proportions and standard deviation of the measured variables, in order to compare the QoL scores from the SF-36. With regard to the variable on the source of funding (health insurance) and sex, the Least Significant Difference test was applied.
For the comparative analysis of the scores regarding the time spent on hemodialysis and education, the variance test (ANOVA) was applied. To test the contrasts, the Levene test was applied to verify the assumption of homogeneity of variance. When homogeneity was verified, Fisher's exact test was used. In cases with no homogeneity, the Tamhane test was performed. For all analyzes, a p-value < 0.05 was adopted.

Results
The study group was made up of 225 randomly selected CKD patients on HD. Thirty-seven patients were excluded because they refused to participate. Thirteen had undergone kidney transplantation, one died, six presented with cognitive impairment that prevented application of the SF36, three presented with Alzheimer's disease and two were hospitalized, thereby leaving a total of 163 patients able to take part in the study (Fig. 1).
The poorest rated dimensions in the SF-36 questionnaire were physical functioning with 31 points ± 31 SD and pain 43 ± 11.58 points ( Table-2).  With regard to education, 34.0% had completed secondary school, which corresponds to between 10 and 12 years of study. While the mean time on hemodialysis (HD) amongst patients was 5.48 ± 5.37 years, 46% had been on HD between one and five years (Table 3).   In the general health component, with regards to the time of hemodialysis, patients who had spent between one and five years (p = 0.024) presented a higher QoL score. No differences were observed between patients with care funded by SUS or by private health insurance (Table 5). No differences were identified between sexes regarding the QoL (Table-5).  * Note: There was a difference in the comparison between the three groups in the roleemotional between the primary school and higher or postgraduate education groups; SD (standard deviation), Min-Max (minimum-maximum score values) Individuals with a higher education and postgraduate education with > 10 years of schooling presented higher QoL scores in role-emotional when compared to primary and secondary education, p = 0.03 (Table-6). Discussion: The increase in the age range of patients on renal replacement therapy (RRT) observed in this study, as in all other countries, may be justified by the increased prevalence of CKD in older people. More than half of the patients on chronic HD worldwide are estimated to be aged over 65 years. Data from the Brazilian Society of Nephrology (SBN) demonstrate a prevalence of over 34% of patients aged over 65 years [18].
In Brazil, similar to the world trend, there has been increase in ESRD and, consequently, a growth of RRT, which has directly affected the number of renal patients, thereby causing a progressive increase of patients on hemodialysis.
A higher percentage of males is observed in most studies and correlates with the higher prevalence of CKD and its progression in men, and in African descendants (multiracial or biracial), which is compatible with the population of Recife, Brazil [19].
The significant number of retired patients with CKD may be justified by the following facts: the increasing age of older people, difficulty in reconciling employment and the process of physical and mental adaptation during the first years of HD [20]. This is consistent with other studies that have demonstrated a negative impact of CKD on financial income, especially during the first year of HD treatment [21] [22].
Having a partner, being married or a family caregiver seems to contribute positively to the QoL. Patients who have family support and find themselves part of a network of affection, obligations and mutual help demonstrate better adaptation to treatment and lower mortality when compared to those who live alone [23]. The literature reveals social support to be an important resource for those suffering with chronic disease, predisposing to a better QoL based on good relationships and positive adjustment to human suffering [23].
Although the education of patients on HD in the present study was above the  [26]. There was evidence of improvement in the physical component after stimulation with regular exercise in patients undergoing HD [29].
However, this is not common practice in hemodialysis satellite clinics in Brazil.
During the first year of hemodialysis, patients undergo a series of physical, psychic and social adaptations. These adaptations have a negative influence over the QoL.
During the first year, this negative impact tends to decrease when uremic toxins are reduced, anemia is corrected, anorexia is reduced and there is muscle mass gain [21]. However, over the years, the chronic complications of CKD begin to surface, such as renal osteodystrophy, osteometabolic disease and left ventricular hypertrophy [28], and the emergence of other comorbidities caused

Conclusions
Hemodialysis may worsen the QoL of patients with chronic kidney disease.
Education and a higher median household income seem to be associated with better QoL indices with regard to role-emotional and physical functioning. The first year of hemodialysis represents the worst period during the QoL of patients, irrespective of social status and income. Among all patients, pain and physical aspects seem to be the critical points in quality of life, regardless of social class or income.

Recommendations
A broader and more humane approach by the multi-professional team is required during the first year. Providing special care in receiving these patients seems to be a turning point in the field of improving the QoL.

Ethical approval
The study complied with all the necessary procedures and was approved by the

Informed consent
Informed consent was obtained from all participants included in the study.

Funding
The researchers declare that this study received no public or private funding.

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