1 Nephrology Unit of the Hospital Central de Asturias and Institute Reina Sofía for Nephrological Research, 2 Nephrology Unit of the Hospital General de Segovia, Oviedo, Spain
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Abstract |
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Methods. A cross-sectional multicentric study was carried out with 485 haemodialysis and renal-transplant patients, using the SF-36 Health Survey to evaluate their HRQOL. SF-36 scores were standardized by age and gender using Spanish normative data. Karnofsky scale score (KS), socio-demographic, and clinical data were also collected.
Results. In renal-replacement therapy (RRT), chronic haemodialysis, and renal-transplant patients, SF-36 standardized scores of elderly patients were higher than in younger patients. Therefore the reduction in HRQOL of elderly patients, in relationship with that of the general population of the same age and gender, was lower than in younger patients. In the case of renal-transplant patients, standardized scores in elderly patients were higher than in the general population for all parameters.
Conclusions. Using standardized scores, elderly patients on renal replacement therapy (haemodialysis and kidney transplant) had relatively better HRQOL than younger patients, and in the case of transplant patients, they had even better HRQOL than in the general population of the same age and gender.
Keywords: elderly; health related quality of life; haemodialysis; kidney transplant; renal replacement therapy
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Introduction |
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Many authors have indicated that age has a negative effect on health-related quality of life (HRQOL) of ESRD patients undergoing haemodialysis [46]. In agreement with this are studies [57] that compared the HRQOL of patients on RRT aged 65 with patients aged <65, which showed that HRQOL of elderly patients is worse than that of younger patients. An additional study affirmed that HRQOL of patients on RRT >65 is worse than that of the general population of the same age [8]. However, other authors [9,10] found that elderly patients have good HRQOL and greater satisfaction with certain aspects of life than younger patients. Finally, some authors have found no differences between renal-transplant patients aged over and under 60 years [11], nor between renal-transplant patients over 60 years and the general population [12]. In Spain, a negative effect of age on HRQOL was found in the general population without disease in a study using a random stratified sample of 9151 subjects [13].
Determining the effects of renal disease and its treatment on HRQOL would be useful for nephrologists to understand the effects of other variables such as age and gender. Therefore it would be useful to analyse HRQOL of patients on RRT and compare it with HRQOL of healthy subjects of the same age and gender. We would therefore be able to eliminate the effect of these variables and analyse more easily the effects of renal disease and its treatment. This method of analysing HRQOL data was proposed by the authors who had developed the SF-36 Health Survey [14], which is the most commonly used generic instrument to assess HRQOL, and was the method used in the present study. We performed standardization by age and gender, using the Spanish general population norms published by a group that translated and validated the SF-36 Health Survey in our country [13].
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Subjects and methods |
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These patients participated in a structured interview, using the validated Spanish version of the SF-36 Health Survey (SF-36) [16], a generic HRQOL assessment instrument that includes eight dimensions: physical functioning (PF), Rol physical (RP), bodily pain (BP), general health (GH), vitality (VT), social functioning (SF), Rol emotional (RE), and mental health (MH), and two summary scores: physical component summary (PCS), and mental component summary (MCS). Each dimension of the SF-36 is scored from 0 (the worst HRQOL) to 100 (the best HRQOL). A standardization of these scores was made, according to age and gender, using the Spanish population normative data [13], obtained from 9151 subjects from a general population. who answered the questionnaire. The formula applied by the authors [14] was:
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Functional status was also evaluated by clinicians using the Karnofsky scale (KS) [17]. In addition, socio-demographic, clinical, and analytical data were collected, including age at the time of interview, gender, socio-economic level divided into three groups: low (<1000 $/month), intermediate (10002000 $/month), and high (>2000 $/month); educational level divided into three groups: low (no schooling), intermediate (primary studies completed), high (secondary or university studies completed); living conditions (patients live alone, with at least one person, or in an institution); time on dialysis treatment; renal disease diagnosis: nephrosclerosis (NE), diabetes mellitus (DM), glomerulonephritis (GN), interstitial nephritis (IN), polycystic kidney disease (PK), others of unknown cause; haemoglobin, serum creatinine, and serum albumin; number of hospital admissions and days in hospital during the previous year. A detailed comorbidity index was collected [18] which included 24 diseases defined by specific criteria. Each disease had five possible scores (from 0 to 4), depending on whether the disease is absent, present but not limiting physical activity, or present and producing light, moderate, or severe limitation of physical activity. The addition of disease scores gives a global rating that ranges between theoretical values of 0 and 96.
This study design was approved by the Hospital Ethic Committee from the Hospital Central de Asturias.
Statistical analysis
Results from quantitative variables were expressed as means±standard deviation (SD), or median with percentiles of 25 and 75. Results from qualitative variables were expressed as percentages. To assess differences between elderly patients (aged 65 years or over) and patients under 65, Student's t-test for unpaired samples was used for quantitative variables, and Chi-square test was used for qualitative variables. Student's t-test was also used to assess differences in SF-36 scores between two populations defined by age (65 years/<65 years). Significance level was set at P<0.05. Statistical analyses were carried out using the SPSS statistical package for Windows, version 7.5.
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Results |
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Differences in renal-transplant patients (Table 2) were not statistically significant for any of the studied variables. However, there were differences according to: socio-economic level (more elderly patients with high levels than younger patients); educational level (more elderly patients with high levels than younger patients); renal disease diagnosis (more younger patients with GN, IN, and DM, and more elderly patients with NE and PK); percentage of patients who had not been admitted during the previous year (greater for younger patients); and the time of hospital stay during the previous year (shorter for younger patients).
Standardized scores of the SF-36 Health Survey are shown in Figure 1 for chronic haemodialysis patients, and in Figure 2
for renal-transplant patients. Each figure compares scores of elderly patients (aged 65 years or over) with younger patients under 65.
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In renal-transplant patients (Figure 2), standardized scores of elderly patients were also higher than those of younger patients, and differences were statistically significant in six dimensions: PF, BP, GH, SF, RE, and MH. Furthermore, the standardized scores of elderly patients were above the general population norms in all dimensions.
The PCS score, which is also standardized according to age and gender (Table 3) was higher in elderly patients than in younger patients in both haemodialysis and renal-transplant subjects (P<0.01).
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Discussion |
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HRQOL score of elderly patients are usually compared with that of younger patients [57] without taking into account the logical age-related differences, shown by others in the general population samples [13]. There is also a tendency to compare HRQOL of haemodialysis patients with that of renal-transplant patients without taking into account the different mean ages of the population samples and the influence that age may have on socio-demographic, clinical, and analytical factors determining HRQOL.
In the present study, socio-demographic, clinical, and analytical characteristics of haemodialysis patients were different between elderly and younger patients. In Table 1, elderly patients on chronic haemodialysis had lower income and educational levels than younger subjects (which also probably occurs in the general population), creating conditions associated with poorer HRQOL in previous studies [19,20]. The frequency of DM and NS was also higher in elderly patients, and have been associated with poorer HRQOL in other previous studies [5,7,20]. The functional status of elderly patients, measured on the Karnofsky scale, was also poorer than in younger patients. It is therefore expected that elderly patients would have worse HRQOL scores than younger patients.
Contrary to our expectations, SF-36 scores standardized by age and gender showed lower reductions of HRQOL in elderly patients on haemodialysis than in younger patients in both physical and mental areas. This is shown in Figure 1, comparing the loss of HRQOL in elderly patients on chronic haemodialysis, which was lower than in younger patients in all the SF-36 dimensions. In other words, elderly patients had better physical functioning, lower level of pain, and better general health perception than patients under 65 compared to subjects of the general population of the same age and gender. The PCS score, which evaluates physical health status, compared with that of the general population of the same age and gender, was also higher in elderly patients (Table 3
). In Figure 1
, HRQOL scores of elderly patients were more similar to those of subjects in the general population of the same age and gender (represented by the baseline) than that of younger patients.
These findings contradict the contributions of some authors [57], who found that elderly patients on chronic haemodialysis have poorer HRQOL than younger patients, but confirm the findings of others [9,10] who report that elderly patients frequently show greater satisfaction with some aspects of their life than younger patients.
Also surprising was the finding that the percentage of patients with no hospital admissions during the previous year was greater for elderly patients (Table 1), and that the length of hospital stay was shorter in elderly patients. In addition the comorbidity index was lower in elderly patients. These facts suggest that there may be a group of elderly patients in good condition who are not included on the transplant waiting list and remain on chronic haemodialysis (because they or their families did not want them to be included on a transplant waiting list, or because their nephrologist did not offer the opportunity). However, a high percentage of younger patients beginning chronic haemodialysis received kidney transplants, and an additional smaller group of younger patients were not able to receive transplants because of their poor physical condition.
In renal-transplant patients, there were no clinical differences between elderly transplant patients and younger transplant patients (Table 2). The slight differences observed were expected. Elderly patients had a greater percentage of NE, a greater percentage of hospital admission during the previous year, lengthier hospital stays during the previous year, and a higher comorbidity index. Therefore and similarly to haemodialysis patients, elderly transplant patients had relative better HRQOL when using standardized scores (Figure 2
and Table 3
) than younger patients both in physical (better PF, lower BP, and better GH perception) and in mental parameters (better social interaction, better RE, and better MH).
Importantly, HRQOL of elderly transplant patients was even better than that of the general population of the same age. Moreover, the physical health status measured by the PCS was higher both in elderly patients, and in haemodialysis patients. The mental health status measured by the MCS was slightly better in elderly patients, but the difference was not statistically significant. The results of the present study agree with and surpass the affirmations of some authors who did not find HRQOL differences between transplant patients aged over and under 60 years [11], nor between patients over age 60 and subjects in the general population [12]. This finding is difficult to explain. HRQOL of younger transplant patients was similar to, but not better than, that of the general population of the same age and gender. To explain this, elderly patients receiving a kidney transplant could have over-valued the improvement of their health status from dialysis to transplant. Furthermore, continuous medical care received at the transplant care unit and a higher socialization could contribute to a significant improvement in the quality of life of elderly transplant patients.
In conclusion, using standardized scores, the reduction in HRQOL of patients on RRT (both haemodialysis and kidney transplant) is lower in elderly subjects than in younger patients. The elderly transplant patients had a HRQOL even better than that of the general population of the same age and gender.
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Acknowledgments |
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Notes |
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References |
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