Health-related quality of life among community-dwelling patients with intractable neurological diseases and their caregivers in Japan

Authors


Mitsunori Miyashita, RN, PhD, Department of Palliative Nursing, Health Sciences, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan. Email: miyasita-tky@umin.net

Abstract

Aims:  The aims of this study were: (i) to clarify the general quality of life (QOL) of patients with intractable neurological disease; (ii) to clarify the general QOL of the caregivers of these patients; and (iii) to explore the association of QOL in patient–caregiver pairs.

Methods:  A cross-sectional survey was conducted between November 2003 and May 2004 among community-dwelling patients diagnosed with Parkinson's disease (PD), spinocerebellar degeneration (SCD), multiple system atrophy (MSA), and amyotrophic lateral sclerosis (ALS) and their caregivers using a mailed, self-administered questionnaire. To measure QOL, we used the Medical Outcome Study 36-Item Short Form (SF-36) for patients and the short form of the health-related QOL scale SF-36 (SF-8) for caregivers.

Results:  A total of 418 questionnaires were analyzed. For the patients, all of the general QOL domains of the SF-36 were significantly lower than the national standard value for all of the diagnoses. Physical function, role physical, and role emotional domains were also low. For caregivers, all of the QOL summary scores of the SF-8 for all diagnoses were significantly lower than the national standard value. Although there were several significant correlations of QOL between patients and caregivers, overall the correlations were low.

Conclusions:  Support for patients with neurological diseases and their caregivers is needed in order to maintain physical and mental QOL.

JAPANESE HEALTH POLICY now provides preferential treatment for patients with various neuromuscular diseases, including Parkinson's disease (PD), spinocerebellar degeneration (SCD), multiple system atrophy (MSA), and amyotrophic lateral sclerosis (ALS), under the framework of ‘intractable diseases’. These diseases are characterized by chronic illness, long-term care, and progressive symptoms. The treatment goal is to maintain quality of life (QOL) in daily living. Therefore, the measurement of QOL for patients with these intractable neurological diseases is an important issue.

To measure the QOL of individuals with intractable neurological diseases, many scales have been developed1 and recently much research focusing on QOL has been conducted.2–9 Many disease-specific scales have been developed for PD, including the Parkinson's Disease Questionnaire-39 (PDQ-39).10–12 Most have used a scale to measure the QOL of PD patients.7–9,13–19 For ALS, although the Amyotrophic Lateral Sclerosis Assessment Questionnaire-40 (ALSAQ-40) is the most commonly used disease-specific questionnaire for ALS,3,20–24 other disease-specific questionnaires25 and individual QOL measures, such as the Schedule for the Evaluation of Individual Quality of Life (SEIQOL), have been used.26–28 On the other hand, although Schrag et al. validated the PDQ-39 for MSA patients, disease-specific scales for MSA and SCD do not exist. To compare the QOL for these diseases, a more general scale is needed.

The Medical Outcome Study 36-Item Short Form (SF-36) is the most frequently used generic QOL scale in the world. The merit of the SF-36 is that it measures general QOL of patients in eight domains of physical functioning and mental health. In addition, the SF-36 is used to compare QOL for patients with disease to the national standard value (NSV) of the general public in the country where the survey is conducted. In fact, the SF-36 has been administered to patients with PD,4,29–32 MSA,33 and ALS.34–37 As mentioned above, although the measurement of QOL of PD and ALS patients has been conducted in Western countries, the study of these patients' QOL is rare in Japan. In addition, the QOL for patients with SCD and MSA has not been studied. Therefore, we designed this study to measure the QOL of patients with these four diseases using a uniform QOL measure, the generic scale of the SF-36.

Furthermore, the general QOL of caregivers has not been investigated. Studies instead have focused on care burden38–42 or depression.43–45 Despite increased subsidization of costs by the Japanese medical insurance system, the heavy burden of home care for these patients has not changed.46,47 In Western countries, studies of caregivers' QOL have been conducted.48–52 However, the quantitative evaluation of QOL for caregivers of patients with intractable neurological diseases (except for burden or depression) has not been conducted in Japan. It is crucial to determine whether a discrepancy in QOL exists between the general population and caregivers in order to decide how to develop strategies to support these caregivers.

As for the association between the QOL of patients and caregivers, Bromberg et al. reported the absence of a correlation, using the SEIQOL.53 However, Jenkinson et al. reported an association for physical and mental function (SF-36) between ALS patients and their caregivers. The association of health-related QOL in patients with intractable neurological diseases and their caregivers is still unclear.

Therefore, we conducted cross-sectional research to clarify the QOL of patients with intractable neurological diseases and their caregivers. The aims of this study were: (i) to clarify the general QOL of PD, SCD, MSA, and ALS patients using the SF-36; (ii) to clarify the general QOL of the caregivers of patients with these diseases using the SF-8; and (iii) to explore the association of QOL among patient–caregiver pairs.

METHODS

Participants and procedures

Participants were community-dwelling patients with intractable neurological diseases and the caregivers providing their home healthcare between November 2003 and May 2004. A self-rated questionnaire was mailed to all patients registered with PD, SCD, MSA, and ALS and their caregivers in Mie Prefecture, Japan. In Japan, the patients with these diseases are registered with the prefecture to receive medical aid. The participants were asked to answer the questionnaire and return the answer sheets. The questionnaires from the patients and their caregivers were returned together.

Measurements

The health-related QOL scale SF-36 for patients54–56

Patients answered the SF-36, version 2 questionnaire. The SF-36 measures general quality of life and is the most commonly used QOL instrument worldwide. The SF-36 has 36 questions and consists of the following domains: ‘physical functioning’ (PF), ‘role physical’ (RP), ‘bodily pain’ (BP), ‘general health perception’ (GH), ‘vitality’ (VT), ‘social functioning’ (SF), ‘role emotional’ (RE), and ‘mental health’ (MH). The responses were based on a Likert scale of 3, 5, or 6 points. We used the Japanese standardized version of the SF-36, version 2. We used the norm-based scoring (NBS) method based on the national standard value. The NBS is standardized with the mean equal to 50 and the standard deviation (SD) equal to 10. This standardization enabled us to compare different domains based on the national standard value. Higher values represent better QOL and scores under 50 indicate that the QOL is worse than that of the general national population. The validity and reliability of the Japanese version of SF-36 were confirmed.

The health-related QOL scale SF-8 for caregivers57

Caregivers answered the SF-8 questionnaire. The SF-8 is the short form of the health-related QOL scale SF-36. The SF-8 consists of the following items: ‘physical functioning,’‘role physical,’‘bodily pain,’‘general health perception,’‘vitality,’‘social functioning,’‘role emotional,’ and ‘mental health’ using Likert scales with 5 or 6 points. We used the Japanese standardized version of the SF-8. We were able to calculate two summary scores, ‘physical component summary’ (PCS) and ‘mental component summary’ (MCS), in accordance with the scoring rule. The standard national values of PCS and MCS are almost equal to 50 and the standard deviation (SD) is almost equal to 10. Higher values represent better QOL and scores under 50 indicate that the QOL is worse than the general national population. For this study, we considered including several care burden scales and a depression scale, but we decided to use the short version of the health-related QOL scale, SF-8, in consideration of the burden to the caregivers.

Participant demographics

We collected information on patients' age, gender, and diagnosis; caregivers' age, gender, relationship to patient, presence of chronic illness, and work status; household income; level of caregiving; duration of caregiving; hours spent caregiving per day; hours required for close supervision of the patient; and number of other persons who assisted with caregiving. The level of caregiving score was assigned according to the Japanese classification of caregiving for the long-term care insurance system (0: none or needs only social support; 1: needs part-time caregiving; 2: needs minimal caregiving; 3: needs moderate caregiving; 4: needs frequent caregiving; and 5: needs constant caregiving). The level of caregiving score was decided by local authorities in accordance with the need for care and the opinion of the primary physician. In the Japanese long-term care insurance system, the medical and welfare services, including financial support for the patient, are determined by the level of caregiving score.

Statistical analysis

First, we determined descriptive statistics from the SF-36 for the patients for each disease condition. We compared the scores of the SF-36 domains to the national standard value. Then, we compared the scores of the SF-36 domains among disease conditions. Second, we showed descriptive statistics of the SF-8 summary score for caregivers of patients for each disease. We compared the SF-8 summary score to the national standard value. We compared the SF-8 summary score among disease conditions. All comparisons were subjected to a multiple regression model adjusted for the age and gender of the patients. Finally, we conducted correlation analysis between patients' SF-36 domains and caregivers' SF-8 summary scores using the multiple regression model adjusted for the age and gender of the patients and caregivers. The significance level was set at 0.05 and two-sided tests were conducted. All analyses were conducted using the statistical package sas Version 9.1 (sas Institute, Cary, NC, USA).

Ethical considerations

Before conducting the study, the ethical and scientific validity was approved by the ethics committees at Mie University Hospital in accordance with the Helsinki Declaration. Each subject was informed in writing that participation in the study was voluntary and their privacy would be strictly protected.

RESULTS

Participant characteristics

The questionnaire was sent to 1577 patients with intractable neurological diseases, and answer sheets were received from 785 (50%). The number of total responders (analysis set) who provided valid final responses was 418 (PD, 273; SCD, 77; MSA, 39; ALS, 29).

Participant characteristics are presented in Table 1. The mean age ± standard deviation (SD) of the patients was 70 ± 9 years, and 52% were female. As for level of caregiving, 48% of the patients scored equal to or greater than grade 3. The mean age ± SD of caregivers was 65 ± 11 years, and 61% were female. The relationship between patient and caregiver was spouse in 76% of cases. Among all responders, annual household income was less than 3 million yen ($US25 000) for 47%. Average duration ± SD of caregiving was 5.6 ± 4.6 years, and average time spent on care was 5.4 ± 4.7 h daily.

Table 1.  Participant characteristics (n = 418)
  • Japanese classification of caregiving for long-term care insurance system.

Patient age, years (mean ± SD)70 ± 9
Patient sex (female)52%
Diagnosis 
 Parkinson's disease65%
 Spinocerebellar degeneration18%
 Multiple system atrophy9%
 Amyotrophic lateral sclerosis7%
Level of caregiving 
 030%
 123%
 222%
 320%
 414%
 514%
Caregiver age, years (mean ± SD)65 ± 11
Caregiver sex (female)61%
Relationship to patient (spouse)76%
Caregivers with chronic illness80%
Caregivers employed25%
Household income, Yen (million) 
 ≤347%
 >3–529%
 >5–712%
 >7–97%
 >95%
Duration of caregiving, years (mean ± SD)5.6 ± 4.6
Time spent caregiving, h/day (mean ± SD)5.4 ± 5.7
Time required for close supervision of patient, h/day (mean ± SD)4.8 ± 6.3
Number of other persons who help with caregiving (mean ± SD)1.1 ± 1.0

Patients' health-related quality of life (SF-36)

Table 2 presents the health-related QOL measured with the SF-36. All of the general QOL domains in the SF-36 for patients in all disease categories were significantly lower than the NSV. The domains of physical function, role physical, and role emotional were consistently low for all the disease conditions. However, the bodily pain domain was significantly different among disease conditions (P < 0.001). The bodily pain domain scores for ALS and PD were lower than the scores for SCD and MSA. In addition, physical function domain scores for SCD, MSA, and ALS were lower than for PD. In the other domains the SF-36 scores were not significantly different among diseases.

Table 2.  Health-related quality of life of patients (Short Form-36)
DomainNSV MeanDisease conditionsP-value
PD (n = 273)SCD (n = 77)MSA (n = 39)ALS (n = 29)
MeanSDMeanSDMeanSDMeanSD
  • The comparison with NSV adjusted for the patient's age and sex: *P < 0.05; **P < 0.01; ***P < 0.001.

  • P-value based on the comparison among diseases adjusted for the patient's age and gender: *P < 0.05;

  • **

    P < 0.01;

  • ***

    P < 0.001.

  • Abbreviations of SF-36 domains: BP, bodily pain; GH, general health perception; MH, mental health; PF, physical functioning; RE, role emotional; RP, role physical; SF, social functioning; VT, vitality.

  • Diseases: ALS, amyotrophic lateral sclerosis; MSA, multiple system atrophy; PD, Parkinson's disease; SCD, spinocerebellar degeneration.

  • NSV, national standard value.

PF37.912.114.1***8.312.4***7.814.1***8.816.5***0.004
RP42.417.412.3***16.413.4***18.217.8***16.715.1***0.60
BP46.933.89.2***38.511.9**40.213.2**31.98.3**<0.001
GH47.031.28.9***32.09.8***29.69.4***29.37.9***0.27
VT49.434.99.6***37.311.3**34.011.9**32.411.6***0.09
SF48.524.414.7***25.715.0***24.615.5***23.618.1***0.93
RE44.819.612.6***23.516.9***21.118.0***20.318.4***0.41
MH50.933.910.9***34.812.1***35.411.6**30.912.4**0.36

Caregivers' health-related quality of life (SF-8)

Table 3 shows the health-related QOL for caregivers measured with the SF-8. All of the general QOL summary scores were significantly lower for all disease conditions compared to the NSV scores. The summary scores of the SF-8 were not significantly different among the disease conditions.

Table 3.  Health-related quality of life of caregivers (Short Form-8)
DomainNSV MeanDisease conditionsP-value
PD (n = 273)SCD (n = 77)MSA (n = 39)ALS (n = 29)
MeanSDMeanSDMeanSDMeanSD
  • The comparison to NSV adjusted for the caregiver's age and gender: *P < 0.05; **P < 0.01; ***P < 0.001.

  • P-value based on the comparison among diseases adjusted for the caregiver's age and gender:

  • *

    P < 0.05;

  • **

    P < 0.01;

  • ***

    P < 0.001.

  • Abbreviations of SF-8 summary scores: MCS, mental component summary; PCS, physical component summary.

  • Diseases: ALS, amyotrophic lateral sclerosis; MSA, multiple system atrophy; PD, Parkinson's disease; SCD, spinocerebellar degeneration.

  • NSV, national standard value.

PCS48.544.28.3***44.49.8**44.27.9*42.09.8*0.46
MCS52.044.27.6***46.07.4**44.56.5**41.99.8**0.12

Correlation of health-related QOL between patients and caregivers

Pearson's correlation coefficients for patients' QOL (SF-36) and caregivers' QOL (SF-8) are shown separately by disease conditions in Table 4. As for PD, several significant correlations were found. The patients' mental health and caregivers' mental component summary were moderately correlated (standardized beta [SB] = 0.34, P < 0.001). As for SCD, four domains for patients (bodily pain, general health, vitality, and mental health) and caregivers' mental component summary were moderately correlated (SB = 0.33, P < 0.01; SB = 0.38, P < 0.01; SB = 0.34, P = 0.01; SB = 0.38, P < 0.01, respectively). As for MSA, bodily pain, patients' general health and vitality were correlated with caregivers' physical component summary (SB = 0.41, P < 0.05; SB = 0.52, P < 0.05; SB = 0.60, P < 0.01, respectively). As for ALS, patients' role emotional was moderately correlated with caregivers' mental health component summary (r = 0.54, P < 0.05).

Table 4.  Regression analysis of correlation between patients' quality of life (QOL) and caregivers' QOL adjusted for patient age and sex, and caregiver age and sex
  SF-36 domains of patients
PFRPBPGHVTSFREMH
  1. * P < 0.05; ** P < 0.01; *** P < 0.001. Figures are standardized regression coefficients of the multiple regression analysis adjusted for patient and caregiver age and sex.

  2. Abbreviations of SF-36 domains: BP, bodily pain; GH, general health perception; MH, mental health; PF, physical functioning; RE, role emotional; RP, role physical; SF, social functioning; VT, vitality.

  3. Abbreviations of SF-8 summary scores: MCS, mental component summary; PCS, physical component summary.

  4. Diseases: ALS, amyotrophic lateral sclerosis; MSA, multiple system atrophy; PD, Parkinson's disease; SCD, spinocerebellar degeneration.

SF-8 summary scores of caregiversPD (n = 273)        
 PCS0.16*0.29***0.26***0.17*0.22**0.16*0.18**0.23**
 MCS0.22***0.17*0.20**0.26***0.28***0.27***0.17**0.34***
SCD (n = 77)        
 PCS−0.030.020.26*0.02−0.03−0.05−0.10−0.12
 MCS−0.010.100.33**0.38**0.34**0.100.190.38**
MSA (n = 39)        
 PCS0.13−0.040.41*0.52*0.60**0.22−0.040.28
 MCS0.320.030.140.150.210.270.060.23
ALS (n = 29)        
 PCS0.08−0.180.000.160.03−0.28−0.250.27
 MCS0.01−0.350.12−0.29−0.190.02−0.54*0.00

DISCUSSION

This is the first large-scale study to investigate the general QOL of patients with intractable neurological diseases and their caregivers in Japan. We found a significantly low QOL for community-dwelling patients with intractable neurological diseases, especially in the physical function and role physical domains of the SF-36. In addition, the general QOL of caregivers measured using the SF-8 was significantly lower than the NSV. Moreover, we explored the correlation between the QOL for patients and their caregivers for the first time. Despite the fact that several significant correlations were found, overall, the correlations were low.

This study has some clinical implications. First, for patients with PD and ALS, bodily pain scored lower compared to the other diseases. Physicians and other medical practitioners should be aware of this finding, because alleviation of bodily pain of PD and ALS is an important clinical issue. For patients with PD, bodily pain might be difficult for clinicians to detect; therefore, PD patients should be carefully assessed for pain. On the other hand, patients with SCD, MSA and ALS had lower scores for physical function than patients with PD. Third, for caregivers, the PCS and MCS were lower than NSV. Thus, social and professional support for caregivers with low PCS and MCS is important because it would contribute to their physical and mental well-being while concurrently improving the patients' QOL.

In Western countries, much research has been done on patients with PD and ALS and their caregivers. However, the QOL of SCD and MSA patients has rarely been studied. Similarly, little is known about the QOL of caregivers who care for patients with SCD and MSA. Investigating the QOL of patients with SCD and MSA and their caregivers is an important issue in Japan. Likewise, the QOL issues for patients with SCD and MSA should be compared to those with PD and ALS. In addition, the healthcare system for Japanese patients with intractable neurological disease differs from that in Western countries. Therefore, these data are valuable for clinicians and policy-makers in Japan and other countries.

As for the patients' QOL, all domains of the SF-36 among all disease conditions scored lower than the NSV. The mean value of the NSV was almost equal to 50, so the mean values of the physical function and role physical domains were very low. These data indicate that there was severe deterioration of physical functioning among community-dwelling patients with neurological diseases. Although physical deterioration is inevitable in such conditions, interventions to maintain function, such as rehabilitation, might be helpful. In addition, the emotional domains, such as vitality, role emotional, and mental health, were lower than the NSV. Usually, physical ability correlates with emotional distress. Psychological assessment and support for patients with intractable neurological diseases is needed. Except for the bodily pain domain, the QOL among patients with these diseases was not significantly different. We need further research on factors that contribute to the differences in physical pain among these diseases.

As for the caregivers' QOL, the summary scores of the SF-8 among all the diseases were lower than the NSV. Previous studies reported that the burden for caregivers of patients with intractable neurological diseases is high in Japan.46,47,58 The care burden or the presence of depression might affect the general QOL of caregivers. Support for caregivers is needed to reduce the care burden and to maintain general QOL.

Overall, the correlations between patients' QOL and caregivers' QOL were low except for a moderate association in several domains. This result is concordant with a previous study that investigated the association between QOL for patients and caregivers using the SEIQOL.53 Surprisingly, the physical function of patients was correlated with caregivers' physical and mental QOL. Usually, deterioration of physical function would result in an increase in the care burden,59–61 and we supposed that the patient's physical function would correlate with caregiver's QOL. The SF-36 for patients is a subjective QOL scale. Subjective QOL might be different from the objective needs of care; therefore, a study including objective care needs would be useful. The physical function of patients correlated with the physical QOL of caregivers only for patients with MSA. In our previous study, the care burden for patients with MSA was highest among these four diseases.61 In MSA, general health and vitality of the patients correlated with the physical component summary score of the caregivers.

On the other hand, the mental component summary scores of caregivers were associated with several emotional QOL domains of the patients. This is a new finding. The lower the patients' mental QOL was, the lower the caregivers' mental QOL. The reason for this correlation is unclear. The emotional distress of patients might affect their caregivers' QOL. Further research is needed in this area. In the future, we intend to investigate the reasons for these correlations. Ultimately, the goal would be to design clinical or social interventions that would improve the caregivers' QOL.

Limitations

The limitations of this study are as follows. First, the response rate among study participants with intractable neurological diseases was low (50%). Our sample was registered under a local governmental registration system for intractable diseases and it included a considerable number of people who did not require care. Thus, the true response rate might be greater than the nominal value. There is a lack of external validity in this study; unfortunately, we were unable to compare background factors between responders and non-responders because personal information is protected by law in Japan. Second, we should note that participants in this study were home caregivers. Institutionalized patients and patients without caregivers were not included. This study is therefore not representative of all caregivers or all patients with intractable neurological diseases. Third, we asked patients and caregivers to return the questionnaires in the same envelope, so patients and caregivers might have seen each other's questionnaires. Therefore, patients may not have answered honestly. We think the caregivers' responses were probably true because we assumed that the caregiver had sealed the envelope. Finally, we did not take into account disease-specific variables, such as severity of disease progression. In addition, previous studies of ALS patients have suggested that non-invasive ventilation increases patients' QOL.6,62 We need to conduct further research including these disease-specific variables.

CONCLUSION

All domains of the general QOL of community-dwelling patients with intractable neurological diseases were significantly lower than the national standard value, especially in the physical function and role physical domains of the SF-36. In addition, the general QOL of caregivers measured with the SF-8 was significantly lower than the national standard value. As for the correlations between patients' QOL and caregivers' QOL, despite the fact that several significant correlations were found, overall, the correlations were low. Support is needed to help patients and caregivers maintain their physical and mental QOL. Therefore, additional research regarding the correlation of QOL between patients and caregivers is essential.

ACKNOWLEDGMENTS

This study was supported by a grant from the Ministry of Health, Labor, and Welfare in Japan for the study ‘Outcomes Research of Specific Diseases’ (PI: S. Fukuhara). We express our appreciation to Sayumi Tanide, Department of Health and Welfare, Mie Prefectural Government, for survey planning.

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