저작자표시-비영리-변경금지 2.0 대한민국 이용자는 아래의 조건을 따르는 경우에 한하여 자유롭게 l 이 저작물을 복제, 배포, 전송, 전시, 공연 및 방송할 수 있습니다. 다음과 같은 조건을 따라야 합니다: l 귀하는, 이 저작물의 재이용이나 배포의 경우, 이 저작물에 적용된 이용허락조건 을 명확하게 나타내어야 합니다. l 저작권자로부터 별도의 허가를 받으면 이러한 조건들은 적용되지 않습니다. 저작권법에 따른 이용자의 권리는 위의 내용에 의하여 영향을 받지 않습니다. 이것은 이용허락규약(Legal Code)을 이해하기 쉽게 요약한 것입니다. Disclaimer 저작자표시. 귀하는 원저작자를 표시하여야 합니다. 비영리. 귀하는 이 저작물을 영리 목적으로 이용할 수 없습니다. 변경금지. 귀하는 이 저작물을 개작, 변형 또는 가공할 수 없습니다.
Doctoral Thesis in Public Health & Social
Medicine
Factors Affecting Depression in Family
Caregivers of People with Dementia: A
Structural Equation Model Analysis
Graduate School of Ajou University
Department of Medical Science
Factors Affecting Depression in Family
Caregivers of People with Dementia: A
Structural Equation Model Analysis
Yunhwan Lee, Advisor
I submit this thesis as the Doctoral thesis in
Public Health & Social Medicine.
February 2020
Graduate School of Ajou University
Department of Medical Science
Eun-Ju Park
The Doctoral thesis of Eun-Ju Park in Medical Science of
Public Health & Social Medicine is hereby approved.
Thesis Defense Committee Chair
Graduate School of Ajou University
December 23, 2019
Member Ki Hong Chun
Member Yunhwan Lee
Member Dae Ryong Kang
Member Soon Young Lee
ABSTRACT
This study aimed to identify the mediating effects of care activity and burden in the relationship between dementia patient’s state and caregiver depression and the moderating effects of social support and social activity. To this end, it tested the hypotheses with structural equation model and the analysis results are as follows:
First, it was found that when the patient’s state was worse, caregiver depression increased, as the impact of patient’s state on depression was significant in the positive (+) direction. Second, it was found that the greater the care burden, the higher the level of depression, as the impact of care burden on depression was significant in the positive (+) direction. Third, it was found that the worse the patient’s state, the more the caregiving activity, as the impact of patient’s state on care activity was significant in the positive (+) direction. Fourth, it was found that the worse the patient’s state, the more the caregiving activity, as the impact of patient’s state on care burden was significant in the positive (+) direction. Fifth, it was found that the more the caregiving activity, the greater the care burden, as the impact of caregiving activity on care burden was significant in the positive (+) direction. Sixth, the mediating effect of care burden between patient’s state and depression was significant. Seventh, the mediating effect of care burden between caregiving activity and depression was significant. Eighth, the impact of patient’s state on caregiving activity was greater in the group with higher levels of social activity, as the moderating effect of social activity appeared to influence the relationship between patient’s state and caregiving activity. It was also found that the moderating effect of social activity influenced the relationship between the patient’s state and care burden, as the impact of patient’s state on care burden
was greater in the group with lower level of social activity.
Despite these results, this study still has limitations in generalizing the findings to all caregivers of patients with dementia. Moreover, causal associations of factors associated with the caregiver’s depression could not be dertermined. Therefore, further studies need to include a divers group of study subjects and variables to test their structural relationships.
Keywords: caregiver depression, patient state, care activity, care burden, social support, social activity
TABLE OF CONTENTS
ABSTRACT ··· i
TABLE OF CONTENTS ··· iii
LIST OF FIGURES ··· v LIST OF TABLES ··· vi ABBREVIATION ··· vii Ⅰ. INTRODUCTION ··· 1 A. Necessity ··· 1 B. Research Question ··· 6 Ⅱ. BACKGROUND ··· 8 A. Caregiver Depression ··· 8
1. Dementia Patient State and Depression ··· 10
2. Care Activity and Depression ··· 11
3. Care Burden and Depression ··· 11
B. Care Burden ··· 12
1. Dementia Patient State and Care Burden ··· 15
2. Care Activity and Care Burden ··· 16
C. Social Support and Social Activity ··· 18
1. Moderating Effect of Social Support ··· 20
2. Moderating Effect of Social Activity ··· 21
Ⅲ. MATERIALS AND METHODS ··· 23
A. Study Model and Hypothesis ··· 23 B. Operational Definition of Variables and Configuration of Measuring
Instruments ··· 28
C. Data Collection and Analysis Procedure ··· 37
Ⅳ. RESULTS ··· 40
A. Demographic Status of the Subjects Surveyed ··· 40
B. Confirmatory Factor Analysis ··· 42
C. Structural Model Analysis ··· 47
D. Moderating Effect Analysis ··· 52
Ⅴ. DISCUSSION ··· 59
A. Summary and Discussions ··· 59
B. Conclusion and Suggestions ··· 67
REFERENCES ··· 70
Appendix ··· 84
Abstract ··· 98
List of Figure
Figure 1. Conceptual Model ··· 24
Figure 2. Hypothetical Model: Direct Effect ··· 25
Figure 3. Hypothetical Model: Mediating Effect ··· 26
Figure 4. Hypothetical Model: Moderating Effect ··· 27
Figure 5. Measurement Model Analysis Result ··· 45
Figure 6. Direct Effect Study Result ··· 50
Figure 7. Moderating Effect of Social Support Result ··· 55
List of Tables
Table 1. Questionnaire Items ··· 36
Table 2. Caregiver Characteristics ··· 41
Table 3. Dementia Patient State ··· 42
Table 4. Measurement Model’s Goodness of Model Fit ··· 44
Table 5. Measurement Model’s Factor Loading ··· 45
Table 6. Correlation of Latent Variables ··· 46
Table 7. Structural Model’s Goodness of Model Fit ··· 47
Table 8. Structural Model’s Parametric Estimation ··· 48
Table 9. Mediating Effect Analysis Result ··· 51
Table 10. Moderating Effect Mode’s Goodness of Fit ··· 52
Table 11. Multiple Group Analysis Result for Moderating Effect of Social Support ··· 53
ABBREVIATION
ADI: Alzheimer's Disease International ADL: Activities of Daily Living BDI: Beck Depression Inventory
BPSD: Behavioral and Psychological Symptoms of Dementia CARE: Caregivers of Alzheimer’s disease Research
CAS: Caregiver Activity Survey
CES-D: Center for Epidemiologic Studies Depression Scale CDR: Clinical Dementia Rating Scale
CFI: Comparative Fit Index
CES-D: Center for Epidemiologic Studies Depression Scale
CREDOS: Clinical Research Center for Dementia of South Korea FIML: Full Information Maximum Likelihood
IFI: Incremental Conformance Index IQR - InterQuartile Range
KLoSA: Korean Longitudinal Study of Ageing NPI: Neuropsychiatric Inventory
MMSE: Mini-Mental State Examination NFI: Normed Fit Index
SEM: Structural Equation Modeling SMC: Squared Multiple Correlations
S-SDQ: Short form of the Samsung Dementia Questionnaire
S-ADL: Seoul-Activities of Daily Living
S-IADL: Seoul-Instrumental Activities of Daily Living
Ⅰ. INTRODUCTION
A. Necessity
Alzheimer's Disease International (ADI) estimates that the world dementi a population is 46.80 million people as of 2015 and will reach 75 million in 2030 and 131.5 million in 2050 (Prince M et al., 2015). This suggests that over 99 million dementia patients are occurring worldwide every year and a new patient occurs every 3.2 seconds.
In Korea, where unprecedented population aging proceeds rapidly, it is expected that the number of dementia patients will also increase rapidly. To look at the dementia patient prevalence rate of Nov., 2017 and the future trends as reported by the Central Dementia Center, it was found that the senior citizens aged over 65 years diagnosed with dementia in Korea are 724,857 people, which reaches 10.18% of the entire aging population, and the dementia prevalence rate by age is 2.2% for 65-69 years, 2.7% for 70-74 years, 9.9% for 75-79 years, 19.6% for 80-84 years and 45.1% for over 85 years, which suggests that dementia patients are increasing with the increasing age. Based on this, it is estimated that the number of dementia patients, or the dementia patient prevalence rate will be one million in 2024, two million in 2039, and over three million in 2050 (National Institute of Dementia, 2018).
If senile dementia occurs, the patients become chronically degenerated and their independent living ability declines markedly due to activity disorder and they desperately require nursing or care from the
surroundings (Hwang et al., 2009). And they require a caregiver only for them although it depends on the progression of disease and the person who takes complete care of the patient spends much part of his/her life and this role is mostly undertaken by families. Among academic studies, Cho(2009) found in domestic studies that 9 in 10 caregivers who take care of the dementia patients are the patient’s families, mostly spouse and 3 in 4 caregivers undergo a serious mental, economic, and social burden, especially depressive symptom and their quality of life is overall deteriorated.
In the midst of such situation, our government began to execute the National Long-Term Care Insurance from Jul, 2008 to mitigate the family’s care burden from senile disorder and dementia in the institutional dimension and from Jul, 2014, designated dementia patient special grade additionally and expanded the support for dementia patients and their families. Despite such national support policy, Lee at al.(2015) points out some limitations. In other words, the caring for dementia patients is being socialized and family’s caring activity is needed despite official provision of in-home service, and so such policy did not have a significant impact on reducing the burden. Also, 91.9%, the dementia patients who have to receive unofficial care from the families because they were not rated and the dementia patients who have to be fully cared by the families even when they were rated, are still high in family’s care burden rate (Korea Institute for Health and Social Affairs, 2014). In fact, the caring for the dementia patients are undertaken a lot by the families (Reinhard et al., 2008) and the pre-experienced nations’ long-term policy direction is moving from the facility-centered to the community or in-home service-centered
(Bolge, 2006), and the expectations of family’s role for unofficial care are increasing more (Kyung, 2017).
As explained in such academic studies, the family who nurses or protects the dementia patient is called as ‘dementia patient family caregiver’ and as they are the people who perform a family care toward the family members of dementia patients who cannot look after themselves based on blood relations and sentiments, they are represented as supporter, family caregiver, and family care provider (Kim et al., 2012; Kim et al., 2007). And dementia patient family caregiver is a very important being for the dementia elderly, but has too much burden as much as they are called as invisible second patient (Brodaty and Donkin, 2009). The conflict between families due to long-term care sometimes causes family disorganization and leads to not only abuse and neglect due to aggravated relationship with the dementia elderly (Pot, 1996; Lee, 2004; Lee and Kolomer, 2005; Cho, 2014) but also to the extreme degree, joint suicide of the dementia elderly and the family caregiver, which becomes a social issue (Kim, 2014).
Therefore, the government has been putting a lot of efforts in solving such social issues and in this respect, is assigning care burden and depression into different unique areas and has sought separately the impact of different variables from the dementia patient caregiver’s dimension and those from the dementia patient’s dimension on care burden vs. on depression (Ministry of Health and Welfare, 2011). And in 2012, the following year, the Ministry of Health and Welfare reported that 62% of the family caregivers looking after the dementia patients in Korea have depression disorder and among which, especially 20% are receiving
psychotherapy. Despite such report that looking after the dementia patient causes psychiatric disability, caregivers are in fact accepting their situation as a natural thing as they recognize it as a result of care burden. Kwon(2018) maintained that the present dementia strategy system has a wide blind spot that is excluded from the policy and lacks direct service for dementia family and caregivers are demanded of the duty of supporting rather than right.
The recent dementia related policies are taking support policies while recognizing caregiver’s burden as a problem, but the support is largely provided for the dementia patients and expecting that care burden will be reduced thinking that supporting the dementia patients will lead to supporting the beneficiary, family caregiver. It is also thought that the reduction in care burden will have an impact on reduction in depression. But many studies on the correlation between care burden and depression exist and some studies see both in the same line, but reducing the care burden is not reducing the depression. So there is a need to make a experiential and comprehensive analysis on the influencing factors on caregiver’s depression including care burden.
Like this, many influencing relationship between caregiver’s depression and care burden has been presented, but the study on through which route care burden has an impact on depression is limited. As the precedent studies suggest that there is a close association between depression and care burden, there is a need to make a more systematic and experiential study on caregiver’s depression. This should be used as the basic data for seeking the effective care plans and providing intervention to mitigate the caregiver’s care burden and minimize the negative results like depression.
Among the positive measures presented by many researchers as an effort to reduce the dementia patient caregiver’s burden or depression to seek care plans, especially social support and social activity are being emphasized. In other words, as social support acts as a direct or indirect factor, the level of care burden can be reduced and it also acts positively to caregivers’ mental health (Pearlin, 1990). And social support serves as an important factor that predicts depression (Rho and Mo, 2007; Lee et al., 2004), and it is also reported that the level of depression is low in the group of living together with family because their social support and family support are high (Park, 2009). Also Park(2011) demonstrated that in the relationship between social support and depression, depression prevalence rate was low at 3.4% when social support was high and depression prevalence rate was very high at 36.4% when social support was low. And Hong(2017) found that the social support recognized by dementia elderly family caregiver adjusted the relationship between care burden and depressive symptom significantly and social support acted as coping resource in stressful situations by reducing the depressive symptom. Social activity has been studied by many researchers as it was recognized as an important strategy to cope with the lost role effectively and it is empirically demonstrated that social activity contributes to the reduction in depression (Jeon, 2017).
Taken the precedent studies above together, among various causes that have been presented as the causes of the burden that dementia patient caregivers undergo and the depression, there are negative causes like patient state and caregiving activity and positive causes like social support
and social activity. Therefore, the necessity of the studies to identify the structural relationship between patient state and caregiving activity that have an impact on dementia patient caregiver’s burden and depression and what roles social support and social activity play can be raised. To identify such structural causal relationship, structural equation modeling is needed and to do this analysis, structural equation modeling will have to be used. The study results drawn from such analysis are provided as basic data for seeking the effective strategic plans to reduce the dementia patient caregiver’s burden and depression.
B. Research Question
This study is an advanced research that is conducted to propose the plans to reduce care burden and depression due to various causes recognized by the caregivers looking after the dementia patients and aims to identify the social and psychological state of the caregivers looking after the dementia patients, object of this study and understand caregivers’ burden and its impact on depression multidimensionally. Also to propose the practical and policy interventions necessary for reducing the care burden and depression depending on social support and social activity as social and cultural capability of the caregivers looking after the patients, this study aims to explore the existing precedent research materials on the influencing factors on caregiver’s depression and analyze the structural relationship between patient state, care activity, care burden, depression,
social support, and social activity.
The research questions that will be addressed in this study for achieving such research purposes are as follows:
Question 1. How about the relationship between dementia patient state and caregiver’s care activity, care burden, and depression? Question 2. What role do care activity and care burden play in the
relationship between dementia patient state and caregiver’s depression?
Question 3. What role do social support and social activity play in the relationship between dementia patient state and caregiver’s care activity, care burden, and depression?
Ⅱ. BACKGROUND
A. Caregiver Depression
Depression is one of the most common mental disorders (Regier et al,1988) and refers to the emotional disorder representing worry, gloom, helplessness, and unawareness ranging from emotional mood changes to morbid condition (Beck et al, 1961) and thus is a total disorder that affects individual’s ability to control thought and behavior due to feeling of helplessness or sense of loss (Holmes, 2002).
In the psychoanalysis glossary, depression is described as affect, i.e. the complex psychophysiological state that includes cognitive and physiological elements as it is the subjective mood such as feeling of sadness, hopelessness, lethargy, guilty feeling, self-critical thought, and reduced interest in outside activities, and the symptoms for the progression of depression include typical boredom, fatigue, reduced sexual desire, loss of appetite or gulosity, constipation, insomnia, and sometimes increased sleep time. Blazer(2003) claimed that depression appears as a reaction to stress and is in the continuum from the normal mood changes to the morbid condition and the level depends on individual’s degree of adaptation. Overall, depression can be classified into three meanings: the first is depression as symptom, which means depressed mood or state, the second is depression as syndrome and means cluster of depressive symptom, and the third is depression as disorder and means a series of clinical characteristics or psychological condition accompanied by impaired function
(Bae, 2006). Depressive symptoms occur by the negative cognitive system of oneself, environment, and the future, and much stress is highly likely to lead to depressive disorder (Kim and Lee, 2000). The main factors of depression are loneliness, economic difficulty, recent experience of stress, family history, experience of psychological damage and violence, alcohol intoxication, drug abuse, unemployment, health problems, and pain (Goldberg, 2006; Park, 2011), and the depression of caregivers looking after the patient is a complex process, but influenced by the patient or caregiver’s general characteristics, ethnicity, and cultural things (Kenneth et al, 2003).
To look at the caregiver characteristics, when the caregiver lacks economic resources, when the caregiver is a daughter or spouse, when the caregiver spends a lot of time in care activity, and when caregiver’s health condition is deteriorated, depression appears high (Levine, 2003), whereas in case of patient characteristics, when the patient state is bad, when the patient is young, when the patient needs caring activity a lot due to deteriorated activities of daily living, and when the problem behavior is severe, depression appears high (Kenneth et al, 2003).
Schulz et al.(1995) demonstrated as a result of considering 41 precedent studies to identify the family caregivers’ degree of physical and mental illnesses that according to the CES-D(Center for Epidemiologic Studies Depression Scale), depression score was 7.4-9.4 point on average in general population group, whereas it was 14-18 point on average in family caregiver group. In all studies investigated, family caregiver’s depression score appeared high.
himself, but if caregiving is compared to one occupational task, the difficulties in caring and maladjustment from depression will have a negative impact on dementia patient.
Since caregiver’s depression status from dementia patient care may lead to the stage of depression as disorder, which influences the daily living and even the entire life, it seems necessary to make a more detailed analysis of caregiver’s degree of depression and the influencing factors and seek the steps and timing of intervention depending on the results from the study.
1. Dementia Patient State and Depression
The precedent studies on the factors that have an impact on depression in dementia elderly family caregivers reported that care situations including dementia elderly’s activities of daily living (ADL) or problem behavior (BPSD) and family caregiver’s coping style and social support have an impact on family caregiver’s depression (Ma and Kim, 1995; Kim, 2002) and that the higher the dementia elderly’s dependence in activities of daily living and the more severe the problem behavior is, the bigger the family caregiver’s depression or stress is (Brodaty and Luscombe 1998; Meshefedjian et al., 1998).
And most studies reported that the more the restrictions on dementia patient’s daily activity, caregiver’s depression increases (Pinquart and Sörensen, 2011; Sung, 2006; Covinsky, 2003; Cho, 1996; Kim, 2001; Yoon et al., 2000; Wright et al., 1994).
2. Care Activity and Depression
Caregivers looking after the senile dementia patient at home spend a lot of time in caring (Stevenson, 1990). Park et al.(2005) reported that caregivers looking after the dementia patient for more than 15 hours occupy 45%. As they have to be with the dementia elderly for all day long, they are isolated from the society and their physical health is aggravated, and simultaneously with the increasing care burden, depression also worsens (Park, 2015).
3. Care Burden and Depression
Many studies have reported on the relationship between the burden that the dementia patient caregivers feel and the depression (Ryu, 2017, Hong, 2017, Park, 2015). Park(2015) found that care burden, subjective health condition, care period, occupation, self-efficacy, quality of marital relationship before caring, and social support in order had an impact on depression and so care burden was found to be a variable that had the biggest impact. It can be said that the caregivers looking after the dementia elderly at home are isolated from the society and their physical health is aggravated because they have to be with the dementia elderly for all day long and at the same time as their care burden increases, their depression also gets severe.
Ryu(2017) reported that there is a high correlation between dementia patient caregiver’s care burden and depression, but both cannot be said as
the same concept and regarded that there are a lot of different opinions about the directivity. They saw that unlike the care burden that individuals feel because they give care for dementia patients, depression is a psychological construct that is influenced by different states other than care situations including care burden and so care burden is a predictor of depression.
The statistical association that care burden has an impact on depression has been supported by the past other studies, too (Bell et al, 2001; Clyburn et al, 2000). On the other hand, there is a study finding that reported that depression is dementia patient caregiver’s determinant of care burden (Kim et al., 2001)
Taken the precedent studies above together, the existing studies reporting that the care burden toward dementia patients has an impact on nursing provider or care provider’s depression have been accumulated and especially care burden from the behavioral characteristics of dementia patients may have a much stronger impact on depression. Accordingly to draw up the measures to reduce the pain of family caregivers, this study aims to make a more detailed review of the factors that family caregivers may have on depression.
B. Care Burden
Care burden is caregiver’s stress from the elderly’s physical dependence and lack of ability in caregiver’s caring process (Poulshock and Deimling, 1984) and so refers to the emotional, physical, social, and financial
difficulties and inconveniences experienced by caregivers in a situation or accident like patient’s change of behavior or state (Zarit, 1980).
About such burden, Clausen and Yarrow from England began to identify the problem of families taking care of the mentally-disordered people in 1955 and Grad and Sainsbury(1963) began to research the burden that families felt and the effects while expressing the responsibility and tension of the families taking care of the mentally-disordered people with the term care burden (Gater et al., 2014). Since then, care burden has been recognized as negative product of care, and many studies explain that care burden is the factor that causes stress, tension, and pain to the main caregivers taking care of the dementia patient (Donaldson et al, 1998).
Zarit et al.(1980) conceptualized family caregiver’s burden as emotional, physical, social or economic stress that caregivers undergo while taking care of the patient based on the subjective feelings of negative experiences, and Thompson and Doll(1982) expanded the concept care burden into the objective burden as well as subjective burden. Subjective burden is defined as caregiver’s subjective feeling and this is expressed with worry, inconvenience, embarrassment or anger, which are the emotional reactions experienced in the caring process, and objective burden is related with the changes that happen in caregiver’s life and the degree of collapse of his life and so expressed with the degree of negative effects that have on social and socializing activity due to care time, number of tasks, and financial tension. Montgomery et al.(1985) also defined care burden as ‘a certain fear or guilty that family member vaguely feels while taking care of the patient.’
shortage of time because too much time was spent for the elderly patient and divided this concept into the time-dependent stress due to shortage of time and the self development stress that is caused when disrupting the self development. Kosberg and Cairl(1986) saw care burden as the cost that has to be paid as a result of care and classified it into the following dimensions: restrictions on social activity, restrictions on personal life, economic cost, and value of providing protection, stress from the relationship with the elderly, and mental and physical difficulty. And Zarit et al.(1986) made an approach from the perceived point of view and for definition, classified it into emotional wellbeing, physical health, social life, and economic state perceived as a result of families taking care of the patient, as the degree of recognizing how painful caregiver’s situation is in taking care of the patient. Bull(1990) defined care burden as ‘stress that caregivers receive in a situation that patient’s self-care function is restricted and patient is depressed due to physical health condition, functional disturbance, and mental health, and divided stress into subjective stress and objective stress. Subjective stress is the negative things such as feeling, attitude, and emotion that caregivers feel in the caring process, and objective stress is the deeds and duties that families have to do and necessary resources according to the patient’s needs.
And regarding the factors of care burden, Yap et al.(2005) claimed that care burden has three major factors: the first is the caregiver’s personal life factor, the second is the negative feelings related to support factor, and the final is the effects of feelings that need to be given to the patient.
In the studies on care burden, the most universally accepted concepts are subjective burden and objective burden, which are more expanded to
encompass the physical symptoms like fatigue and lack of sleep and psychological symptoms like depression, anger, anxiety, and guilt, which can be experienced by caregivers as a consequence or result of care and social and economic problems including isolation and leisure activity restrictions multidimensionally (George and Gwyther, 1986; Lee and Kim, 2003; Han et al., 2015; Kang et al., 2017).
To reduce the care burden, with the expanded concept of care burden, there is a need to analyze the factors that have an impact on care burden in various ways.
1. Dementia Patient State and Care Burden
Care burden is primarily associated with the characteristics of care experienced by caregivers, in other words, the symptoms that dementia patients show. The Ministry of Health and Welfare(2009) claimed that the biggest impact on dementia caregiver’s burden, among degraded cognitive function, failure in daily living activity, and problem behavior that dementia patients show is patient’s problem behavior. In measuring the group of neurobehavioral symptom with Zarit’s care burden scale, it appeared that the more the subjects’ problem behavior, caregivers felt burden and depression. In the group of neurobehavioral symptom, restlessness or aggressive attitude aggravates the relationship with caregivers and the aggravated relationship again causes more severe behavioral problems from the patient who receives care, which is a repetitive vicious cycle (Rachel et al., 2005).
of 228 care burden studies, patient’s neurobehavioral symptom is a strong predictive factor of dementia care burden than any other factors, many roles that have to be performed by caregivers cause conflict, which leads to the conflict in the entire family interaction if the role readjustment in a family fails (Kwon et al., 2002), and this may be a factor that can give severe care burden to all the families.
Besides, neurobehavioral symptoms unadjusted of dementia patient like aggression, in fact, add to the caregiver’s burden as a factor that cannot accept the patient into the nursing facility. Song et al.(2013) claimed that dementia severity is judged as cognitive disorder, neurobehavioral symptom, and deteriorated activities of daily living and the dementia severity increases the main caregiver’s care time and the care burden as well.
Especially in the damaged cognitive function, main symptom of dementia among the dementia elderly related characteristics, the greater the extent of damage, the higher the family caregiver’s care burden increases (Bae et al., 2006; Ma, 1998; Kim and Choi, 1993) and dementia elderly’s impaired activities of daily living also have a strong impact on care burden (Kim and Choi, 1993; Lee et al., 2015). Cho et al.(2010) maintained that going to the bathroom, moving, toilet training, and eating, among the activities of daily living have a statistically significant impact on care burden.
2. Care Activity and Care Burden
Various causes of care burden that the dementia patient caregivers feel have been presented, but among which, care activity is emphasized. In
other words, dementia severity increases the main caregiver’s care time and raises the care burden depending on the degree (Song et al., 2013), and if the effort and time for looking after dementia elderly increases due to dementia elderly’s problem behavior and dependence, the caregiver feels substantial care burden in physical, emotional and economic aspects (Lee et al., 2008).
The important factors that have an impact on caregiver’s burden are care period, time for providing care in a day, and care intensity. As the social supports network collapses by the long-term care, social isolation deepens and caregiver’s care increases.
And Kwon et al.(2015) mentioned after analyzing multiple precedent
studies on care burden that care time has an impact on care burden and one of the painful factors of care burden that dementia elderly caregivers especially feel the most strongly is the relationship between role constriction and care time. Due to the role constriction that threatens even the existing everyday life, caregivers lose their sense of self and lead to anger at the patient, and the burden from the role constriction is aggravated as the time to look after the patient increases and so the care time cannot be separated in understanding care burden. The more the care time becomes, the care burden increases and if one should take care for all day, care burden appears greatly and care burden diminishes if shared rather than if taken care alone, and so this showed a close association between care time and care burden.
Also, Kim et al.(2004) analyzed the precedent studies and summarized as follows the significance of utilizing care time to evaluate the care burden more objectively. If the caregiver spends time in caring for the
dementia patient, the time for doing a productive work lessens relatively, which reduces the income in the end. Therefore, measuring the care time can be an indirect indicator of economic burden by the dementia and so used as efficacy measurement index in the drug trial research on dementia patients. And it was said that care time has a significant correlation with the depth of dementia symptoms like functional disorder and failure in activities of daily living and also has a significant correlation with caregiver’s stress and inconveniences.
Other opinions on care time have been reported. It is predicted that if social supports network collapses by the long-term care, social isolation deepens and caregiver’s burden increases, but Zarit et al.(1986) reported that as the period of outbreak elapses, the care burden becomes low and Mun(1998) claimed in the analysis on the routes for the quality of life of dementia elderly and families and their social welfare support plans that burden worsens in early stages of dementia. Monteko(1989) also reported that the longer the disease duration becomes, frustration diminishes. It is predicted from this that acceptance of care and adaptability to it increased.
C. Social Support and Social Activity
Social support means help and aid provided by family, friend, neighbor, and others (Park, 1985) and in multidimensional nature of social support concept, social support is classified into four categories: material support, informative support, emotional support, and self-esteem support (Cohen and Hoberman, 1983) or social support is conceptualized into emotional support,
informative support, material support, and evaluative support (Park, 1985). Like this, every researcher presents different conceptual classifications.
At this time, emotional support means stability that one’s feelings are understood through sympathy and one receives positive attention from others, and includes emotional support provided by others when one is in trouble (Sherbourne and Stewart, 1991). This is happened through unofficial channels from close people like family, friend, and special people rather than through official channels. Substitute family means the presence of substitute family who can support household affairs including housework instead of main caregiver and keep the patient state or handle inconveniences. Finally care support means being provided education about in-home service agency and facilities and education necessary for looking after patients.
There has been no consensus on the conceptual definition on social activity. Every researcher has defined it in various ways: participation, social activity, social integration, or involvement in society (Gi, 2019). Likewise, social activity is also called as social participation activity, has a similar meaning to social integration as a contrast to social exclusion or alienation (Park Changje, 2015), and refers to involvement in volunteer activity, hobby activity, leisure gathering religious event, community action, income seeking activity, leisure event, educational activity, and civic group (Park et. al.(1994).
Aging Panel Survey (2014) classifies social participation into the following six types: religious activity, socializing activity, leisure activity, reunion and clan gathering activity, volunteer activity, and party and civic group activity, and defines social participation as social activity in a limited
sense and one’s exercise of right activity in the broadest sense. 1. Social Support’s Moderating Effect
Social support serves as an important factor that predicts depression (Rho and Mo, 2007; Lee et al., 2004), and Park(2009) reported that in the group of living with families, social support and family support are high and so the level of depression is low. Also in Park(2011) on the relationship between social support and depression, it appeared that if the social support is high, the depression prevalence rate is low at 3.4%, and if the social support is low, the depression prevalence rate is very high at 36.4%. Like above, the precedent studies suggested that social support is a factor that has an impact on depression.
Domestic studies also regard social support as important dependent variable that has a direct impact on family caregiver’s care burden, but Park and Park(2015)’s recent study on the moderating effect of social support reported that the entire effect of social support is at the middle and lower level.
It has been revealed through various precedent studies that emotional, physical and social difficulties from care burden can be alleviated through social support. In other words, social support serves as a direct or indirect factor and can reduce the level of burden and acts positively to caregivers’ mental health (Pearlin, 1990).
In fact, among the caregivers who had experienced high stress due to Alzheimer-type dementia patient’s behavioral problem, their depression was
reduced when their time with families and friends increased and they experienced different kinds of informative support (Clyburn, 2000). In the same context, Atienza et al.(2001)’s study on caregivers who participated in mental health promotion program also found that social support increases the ability to control a situation and acts as a moderating variable between care burden and negative emotion.
2. Social Activity’s Moderating Effect
Socioeconomic activity discontinuance may weaken the role of the members of the society and cause negative results like social isolation or depression, but conversely, can reduce the negative results by reinforcing the role as the member of social community and that as the member of the family so that they can use the time left in involving in social activity and activities with families (Kim Jeongseok, 2007).
Kim(2000) claimed that in social aspects of care burden experienced by dementia elderly supporters and families, socioeconomic activity discontinuance means changes to negative relationship between family, patient and children and restrictions on social activity. And Poulshock and Deimling(1984) classifies the effects of support into the following two factors: negative change of elderly-supporter relationship and supporter-family relationship and restrictions on social activity.
Regarding the social activity’s moderating effect, it was found from Hong(2016) that social activity frequency did not show a significant result on burden, but in terms of depression, depressive symptom was higher in group of participating in one or two activities than in group of
participating in three activities and depressive symptom was higher in group of participating in three activities than in group of participating in four or five activities, which showed a significant difference between respondent groups. It was also seen that the higher the care burden, the more the degree of depressive symptom changed remarkedly depending on the degree of social support.
Bae et al.(2018) found that in Korean adults aged 45 years or higher, the degree of social activity participation has an impact on the occurrence of depression and in early middle age, the lower the degree of social activity participation, the risk of depression increases significantly.
Haley et al.(1996) claimed that the negative effects on the wellbeing of caregivers which can be caused by the source of stress by the caregivers can be changed by social resources like social support and social activity.
Taken the investigated contents from the precedent studies above together, the necessity of research on the role of caregiving activity, care burden, social support, and social activity in the relationship between dementia patient state and caregiver depression can be raised.
Ⅲ. MATERIALS AND METHODS
A. Research Model and Hypothesis
To look at the investigated contents from the precedent studies, as the cause that is identified most importantly about dementia patient caregiver’s depression, patient state is being emphasized (Jang, 2013; Hong, 2016), and caregiver activity (Kim, 2000; Bae et al., 2018) and burden (Pearlin, 1990; Tennstedt, McKnightly and Sullivan, 1989) are also reported as the factors that have an impact on depression.
And based on the studies that social support and social activity have a positive impact on dementia patient caregiver (Park and Park 2015; Rho and Mo, 2007; Lee et al., 2004) as well as the studies that patient state causes care activity (Kwon et al., 2002), the studies that patient state also has an impact on care burden (Song et al., 2013; Bae et al., 2006), and the studies that there is a significant relationship between care activity and care burden (Song et al., 2013; Kwon et al., 2015), this study set the conceptual model like in <Figure 1> below.
In the research model set up, as the cause that is identified most importantly about the dementia patient caregiver’s depression, patient state is being emphasized (Jang, 2013; Hong, 2016), and based on the investigated contents from the precedent studies that caregiver activity (Kim, 2000; Bae et al., 2018) and burden (Pearlin, 1990; Tennstedt et al., 1989) are the factors that have an impact on depression, the studies that patient state has an impact on care burden (Song et al., 2013; Bae et al., 2006), and the studies that there is a significant relationship between care activity and care burden (Song et al., 2013; Kwon et al., 2015) and the studies that patient state causes care activity (Kwon et al., 2002), we presented the following direct effect hypothesis and the direct effect hypothesis model like in <Figure 2>.
<Figure 2> Hypothesis Model: direct effect
H1-1. Dementia patient state will have a significant impact on caregiver depression.
H1-2. Dementia patient state will have a significant impact on caregiver’s activity.
H1-3. Dementia patient state will have a significant impact on caregiver burden.
H1-4. Dementia patient caregiver’s activity will have a significant impact on the burden that they feel.
H1-5. Dementia patient caregiver’s activity will have a significant impact on their depression.
H1-6. Dementia patient caregiver’s burden will have a significant impact on their depression.
Inferring from the investigated contents from the precedent studies so far and the Research Hypothesis H1, we presented the following mediating effect hypothesis and the mediating effect hypothesis model like in <Figure 3>.
H2-1. Caregiving activity will have a significant mediating effect in the relationship between dementia patient state and caregiver depression.
H2-2. Care burden will have a significant mediating effect in the relationship between dementia patient state and caregiver depression.
H2-3. Care burden will have a significant mediating effect in the relationship between dementia patient caregiver’s activity and depression.
Furthermore, based on the studies that social support and social activity have a positive impact on dementia patient caregiver (Park and Park, 2015; No and Mo, 2007; Lee et al., 2004), we presented the following moderating effect hypotheses and the moderating effect hypothesis model like in <Figure 4>.
H3-1. Social support will have a significant moderating effect on each route between dementia patient state, caregiver’s activity, burden, and depression.
H3-2. Social activity will have a significant moderating effect on each route between dementia patient state, caregiver’s activity, burden, and depression.
B. Operational Definition of Variables and
Configuration of Measurement Tools
1. Depression
Depression refers to emotional disturbance representing worry, gloom, lethargy and valuelessness ranging from emotional mood changes to pathological condition (Beck et al., 1961).
This study tells the scores measured by BDI.
BDI screening test is a depression diagnostic scale that measures the depressive symptom, developed by Beek(1961) and composed of 21 question items including cognitive, emotional, synchronous, and physical symptom areas of depression.
By comprehensively summarizing the symptoms that appear a lot in depressed patients who receive psychotherapy and patients’ attitudes, we extracted 21 question items and scaled them. Subjects were asked to
respond to the specific statements representing the degree of symptom for each question item.
They are encouraged to choose the contents that represent their mood state the best for the past one week among the four items summarized by symptom. Each question item was scored in a 4-point scale ranging from 0 to 3 point and evaluated in the category of 0-63 point.
To look at the content and score of the first question item, I don't feel sadness =0 point, I feel sadness =1 point, I always feel sadness and can’t dispel it=2 point, and I am so sad and unhappy and can’t endure it=3 point. In interpreting the result, the cutting point for diagnosing the depression is presented at 21 point in Korea. But in general, 0-9 point is understood as non-depressed state, 10-15 point as mild depression state, 16-23 point as heavy depression state, and 24-63 point as severe depression state.
As a result of reliability analysis of 21 question items for depression conducted in this study, it was found that Cronbach's α was .971, which showed a high reliability.
2. Dementia Patient State
Most studies pointed out that dementia elderly’s functional disturbance is
the primary care burden inducing factor, based on whichever conceptual
definition, among various concepts on care burden. Especially dementia elderly’s functional disorders, the cognitive disorders including memory
disorder, disorientation, and impaired judgment and the accompanying
psychiatric symptoms and problem behaviors are regarded as the most
In this study, dementia patient state means a value identified by measuring S-SDQ, NPI, S-ADL, and S-IADL.
(A) Patient’s Cognitive Function (S-SDQ)
Cognitive function refers to memory, orientation, attention, language, perception and neuromotor function (Kim et al., 2005). In this study, we used the score measured by S-SDQ developed by Choi et al.(1996). This instrument consists of 15 question items measuring patient’s cognitive function state and daily activity function based on the reports by the families living with the dementia patient. Total sum of the scores for question items was 30 point. If the score is 8 point or higher, dementia is suspected. This instrument has an advantage in that it can distinguish the possibility of dementia in a short time and is relatively less influenced by patient’s education level and age. But it has limitations in that patient evaluation can depend on the families who are subject to the test and the test only relies on the questionnaire without face to face with the patient.
As a result of reliability analysis of 15 questions for patient’s cognitive function conducted in this study, it was found that Cronbach's α was .932, which showed a high reliability.
(B) Patient’s Problem Behavior (NPI)
This study measured patient’s problem behavior with the
Neuropsychiatric Inventory (NPI). The formula of scoring is frequency of behavior symptom (0, 1) multiplied by severity (1=mild, 2=moderate,
3=severe). This means that the higher the total score, the more severe the overall problem behavior. Also the caregiver’s level of pain by item (0=not at all, 1=very low, 2=mild, 3=moderate, 4=severe, 5=very severe) was evaluated and the obtained value was multiplied by patient’s problem behavior for calculating the total score. The higher the total score, the bigger the caregiver’s pain.
Neuropsychiatric Inventory was evaluated with more than 12 abnormal behavior symptoms that appear commonly in the dementia patients -delusion, hallucination, agitation/aggression, depression/dysphoria, anxiety, euphoria/elation, disinhibition, irritability/instability, apathy/indifference, aberrant motor behavior, sleep/night-time behavior, appetite/eating change, and simultaneously subsequent caregiver’s level of pain is evaluated. This is not only useful for evaluating the psychopathology of dementia but also helpful for determining the type of dementia and observing the changes of symptom depending on treatment effect. Moreover, it has a big advantage in that caregiver’s level of pain can be evaluated and this can be reflected into treatment.
As a result of reliability analysis of patient’s problem behavior conducted in this study, it was found that Cronbach's α was .951, which showed a high reliability.
(C) Patient’s Activities of Daily Living Evaluation (S-ADL, S-IADL) The skill required for human’s daily activities consists of daily activity skills-basic required for taking care of one’s body and daily activity skills-instrumental required for enjoying social activity. In this study, we
measured the daily activity skills-basic and the daily activity skills-instrumental through the interview with patient caregivers by the clinicians who were well-informed of how to implement, with S-ADL and S-IADL developed by Gue et al.(2004).
Total score of S-ADL ranged from 0 point to 24 point. This means that the higher the score, the more difficult the independence performance of the daily activity skills-basic. S-IADL consists of 15 question items in a 0~3 point scale. The score range is from 0 point to 45 point. and the sum of raw scores is calculated before evaluation. Therefore, the higher the score of S-IADL, there is more disturbance in daily activities-instrumental. Also considering the cultural difference or gender difference, it was divided into ‘currently executing’ and latent ability for evaluation. “Currently executing” is the degree that the patient currently can perform the instrumental daily activities independently. On the other hand, “latent ability” is the ability to perform considering the patient’s latent ability despite the current inability to perform the instrumental daily activities independently.
The score range of S-IADL was from 0 point to 45 point. This means that the higher the score is, the performance of instrumental daily activities required for social life deteriorates.
As a result of reliability analysis on patient’s daily activities evaluation conducted in this study, it was found that Cronbach's α (basic) was .942 and Cronbach's α (instrumental) was .952, which showed a high reliability.
To measure care time, two methods have been used: recording the total time used for helping with dementia patient’s activity and fragmenting the time used for helping with a certain activity. The example for the latter is represented by Caregiver Activities Time Survey and CAS(Caregiver Activity Survey).
CAS was designed to investigate the information on the time that dementia elderly supporters spared for the past 24 hours from the time of the investigation (Davis et. al.,1997). CAS was segmented into the following six subareas related to assistance with dementia patient’s activities of daily living and behavioral management: communicating with the person, using transportation, dressing, eating, looking after one's appearance, and supervising the person. In this study, we measured by recording total hours a day.
4. Care Burden
Care burden is defined as a physical and mental or psychological or emotional/social/economic problem experienced by the family members who take care of the elderly who are disabled (George and Gwyther, 1986). In this study, we used the score measured by Zarit et al.(1986)’s Zarit Burden Interview. This scale is composed of total 22 question items asking caregivers how they felt about health, finance, social life, and interpersonal relationship while looking after the dementia patient. The type is a self report, and the responses to the question how often caregivers feel about each question were scored at “not at all=0”, “very occasionally so=1”, “sometimes so=2”, “often so=3”, and “almost always so=4.” The total score
was 88 point. Usually, 0-20 point is classified as no burden or extremely mild, 21-40 point as mild to moderate, 41-60 point as moderate to severe, and 61-88 point as severe. This means that in general, the higher the score, the bigger the care burden. If it is 51 point or higher, the care burden means rather high. If it is 69 point or higher, it means very high.
As a result of reliability analysis of care burden conducted in this study, it was found that Cronbach's α was .938, which showed a high reliability.
5. Social Support and Social Activity
Social support is a subjective thing recognized by the family care providers and thus refers to a physical and psychological help that subjects receive through interpersonal interaction with spouse, family, friend, and neighbor (Norbeck, et al., 1981). This study has three subfactors of emotional support, instrumental support, and care support for social support and classified the group into two groups: the group who receives social support perceived by individuals and the group who does not.
As a result of reliability analysis of social support conducted in this study, it was found that Cronbach's α was .606, which showed a moderate reliability.
Individual’s social participation activity is sometimes limited to one activity, but many people are participating in multiple social activities including socializing activity among relatives or friends, religious activity, sports activity, and volunteer work activity. Therefore, as the necessity of conducting a study encompassing the entire social participation activity rather than analyzing the effect of one social participation activity has been
raised (Jeon, 2017), social activity was used as the item for measuring the social activity participation level included in Aging Research Panel Survey.
The seven questionnaire items for identifying how often they participated in social activity for the past one month included meeting with relatives, friends, and neighbors, participation in religious gathering including church, Catholic church, and temple, leisure activity, club and social gathering, political/social organization participation, learning/teaching activity, and volunteer work activity, and the presence of care for the others other than patient was scored in the following manner: not at all=0, once a month=1, 2~3 times a month=2, once a week=3, 2~3 times a week=4, and 4 times a week or more=5, and the group was divided into two groups: the group who participated in social activity a lot and the group who did not for analysis.
As a result of reliability analysis of social activity conducted in this study, it was found that Cronbach's α was .642, which showed a moderate reliability.
6. Configuration of Survey
In this study, the important variables are patient state, caregiving activity, care burden and depression, and social support and social activity. Accordingly, this study extracted the items that were important variables for this study and conducted analysis based on the questionnaire items of CREDOS.
The questionnaire items in the measurement tools used for this study are like in <Table 1> below.
<Table 1> Questionnaire items
Dependent variable depression was composed of 21 question items and independent variable patient state was composed of largely 15 question items for cognitive function, 12 for problem behavior, 15 for activities of daily living-basic, and 12 for activities of daily living-instrumental (total 44). Intervening variable caregiving activity was composed of largely two items: 1 for time and 1 for number of days. And mediating variable care
Constructs Variables Number
of items Supporting literature
Careegiver Depression BDI 21 Beek(1961)
Dementia patient
S-SDQ 15 Choi et al.(1999)
NPI 12 Folstein et al.(1975)
S-ADL 12 Gu et al.(2004)
S-IADL 15 Gu et al.(2004)
Care Activity Time(CAS) 1 kim et. al(2004)
Day 1
Care Burden ZBI 22 Zarit et al.(1980)
Social support
Emotional
3 KLoSA(2010) Instrumental
Care
Social Activity 7 KLoSA(2010)
Caregiver characteristics Age 5 CREDOS Gender Income Education Relationship total 114
burden was composed of 22 items, and moderating variable social support was composed of 3 items and social activity of 7 items. Personal background was composed of total 5 items including gender and age. Therefore, the total number of questions was 114.
C. Data Collection and Analytical Procedure
1. Data Collection
This study used the data from The CARE Study: Caregivers of Alzheimer’s Disease Research. The survey was conducted in cooperation with 12 medical institutions nationwide including Ajou University Hospital, Gachon University Gil Medical Center, Bucheon St. Mary’s Hospital Catholic University, Konkuk University Medical Center, Kwandong University Myungji Hospital, National Health Insurance Ilsan Hospital, Dong-A University Medical Center, and the questionnaire was administered in one-on-one interview by trained nurses.
The subjects selected were the main caregivers of the patients who were included in the patient inclusion criteria. The family members (spouse, daughter-in-law, daughter, son, etc) who spent the most time in looking after the patient were selected. The patient inclusion criteria included subjects of follow-up investigation who were registered in the CREDOS(Clinical Research Center for Dementia of South Korea) database, and they were the patients who were diagnosed with Alzheimer's disease or subcortical vascular dementia. The period of investigation was from
2012 till 2013 as first year survey, and among 600 main caregivers of the patients who are residing at home at the point of survey, 476 caregivers only were used for our final analysis.
And interview research was conducted after signing the informed consent and approved from the Ajou University Medical Center Institutional
Review Board(AJIRB-MED-SUR-12-046).
2. Analytical Procedure
The analytical procedure conducted in this study is as follows:
First, for refining the data used in this study, we conducted a missing value test, normality test, and outlier test. The samples whose response rate was low in the missing value test were removed by the Listwise deletion method, but in nature of survey content, the presence of missing values should also be considered and so some missing values were allowed. For normality test, skew and kurtosis were drawn And it was found that skew was less than 2, absolute value and kurtosis was less than 4, absolute value. For the items beyond the normality, we conducted outlier test, and the samples that were outliers beyond IQR*1.5 were removed by the Listwise deletion method.
Second, for identifying the sociodemographic status of the subjects surveyed, we conducted frequency analysis.
Third, for identifying the validity of the measurement tools, we conducted confirmatory factor analysis. At this time, some missing values were allowed. So we used FIML(Full Information Maximum Likelihood).
analysis. For mediating effect testing, we conducted Sobel test, and for moderating effect testing, we used the parametric comparative analysis from the multiple group analysis.
The analysis so far was conducted with statistical package programs SPSS 20.0 and AMOS 20.0.
Ⅳ. RESULTS
A. Demographic Status of Subjects Surveyed
The number of subjects who responded to the survey for this study was 600 individuals in the beginning, among which, the samples who were removed by the Listwise deletion method because the response rate was low or the response was odd was 124. Therefore, the final sample for the analysis was 476 individuals, and the results of frequency analysis conducted for identifying such sociodemographic status appeared like in <Table 2> below.
Among the total 476 individuals, there were 154 males (32.4%) and 322 females (67.6%). In the relationship with dementia patient, spouse occupied 183 individuals (38.5%), which was the highest, daughter 127 (26.7%), daughter-in-law 82 (17.2%), and son 72 (15.1%). In average monthly income level, 1.5 ~ 3.5 million won occupied 185 individuals (39.0%), which was the highest. In academic ability, high school graduate occupied 170 individuals (35.7%) and college graduate 161 (33.8%). The care period for dementia patient was 4.3 years on average, 26.5 days on monthly average, and 14.1 hours on daily average. And care burden showed 40.5 point on average in the range from point 0 to point 88, and depression showed 14.1 point on average in the range from point 0 to point 59.
<Table 2> Characteristics of Caregiver Categories mean ± SD / N (%) Age (y) 57.0 ± 13.0 Gender Male 154 (32.4) Female 322 (67.6)
Relationship to patient Spouse (M) 76 (16.0)
Spouse (F) 107 (22.5) Daughter-in-law 82 (17.2) Son 72 (15.1) Daughter 127 (26.7) Others (Son-in-law ) 12 (2.5) Monthly income(won) <150 153 (32.2) 150-350 185 (39.0) ≥350 136 (28.7)
Education level No formal education 11 (2.3)
Elementary school 46 (9.7)
Middle school 61 (12.8)
High school 170 (35.7)
College or university 161 (33.8)
Graduate school 27 (5.5)
Duration of caring (y) 4.3 ± 4.6
Caring day per month (d) 26.5 ± 8.2
Caring time per day (h) 14.1 ± 8.4
ZBI 40.5 ± 20.2
BDI 14.1 ± 10.0
* Characteristics of the categorical variables described as N (%), and characteristics of continuous variables described as Mean (SD)
And the results of descriptive statistic analysis conducted to look at the status of dementia patient state appeared as shown in the following <Table 3>.
<Table 3> Dementia Patient state Categories mean ± SD
S-SDQ 21.3 ± 7.4
NPI 39.1 ± 36.1
S-ADL 5.9 ± 6.5
S-IADL 28.5 ± 13.1
Cognitive function (S-SDQ) was at 21.3 point on average in the range from point 0 min. to point 30 max. Problem Behavior (NPI) appeared at 39.1 point on average in the range from point 1 min. to 180 point max. And Activities of Daily Living-Basic(S-ADL) appeared at 5.9 point on average in the range from point 0 min. to 24 point max. and Activities of Daily Living-Instrumental (S-IADL) appeared at 28.5 point on average in the range from point 0 min. to 45 point max.
B. Confirmatory Factor Analysis
The measurement tools used in this study are depression, patient state, care activity, care burden, and social activity. Dependent variable depression consisted of 21 question items, and independent variable patient state consisted of a total of 54 question items: largely 15 question items
for cognitive function, 12 for problem behavior, 12 for Activities of Daily Living-Basic, and 15 for Activities of Daily Living-Instrumental. Intervening variable caregiving activity consisted of a total of two items: largely 1 item for time and 1 item for number of days. And intervening variable care burden consisted of 22 question items and moderating variable social activity consisted of 7 question items.
To identify the configuration system and theoretical validity of this measurement tool, we conducted a measurement model analysis as one of the confirmatory factor analyses. But, we used Full Information Maximum Likelihood (FIML) for parametric estimation, since some missing values were allowed. Also the number of appropriate samples for structural model analysis can be calculated by the following formula.
Structure equation modeling’s appropriate number of samples = 1.5 × p(p+1)
*p=number of measurement variables *Source: Bae(2011), 174.
When we substituted 8, number of measurement variables for the structural equation modeling presented in this study into this formula, the number of appropriate samples was drawn as 108.
But according to the Monte Carlo simulation, minimum number of samples for the structural equation modeling should be 200 or higher (Bae, 2011), and it was reported that if the sample size is more than 400, ML reacts sensitively and so the model fit gets bad (Bae, 2011). Given that the number of samples for the analysis in this study is more than 400, we
presented NFI(Normed Fit Index), IFI(Incremental Fit Index), and CFI(Comparative Fit Index) that did not react sensitively to the number of samples.
According to the analysis, the goodness of model fit appeared like in <Table 4> below.
<Table 4 > Measurement model’s goodness of model fit
Index of fit NFI* IFI* CFI*
Standard >.90 >.90 >.90
Goodness of fit 0.905 0.920 0.918
* NFI(Normed fit index): is an index representing how much the proposed model has improved compared to the basic model. If it is generally 0.90 or higher, it is regarded as acceptable.
* IFI(Incremental fit index): has a value from 0 to 1. If it is 0.9 or higher, it is judged as a good fit.
* CFI(Comparative fit index): was developed from the perspective of indicating parameter and distribution of parent population to complement NFI. has a value from 0 to 1. If it is 0.9 or higher, it is judged as a good fit.
In the goodness of model fit of the measurement model, it appeared that NFI, IFI, and CFI all were 0.9 or higher and so the model was judged to be appropriate.
And the results of parametric estimation to identify the factor loading of the measurement model appeared like in <Table 5> and <Figure 5> below.
<Table 5> Measurement model’s factor loading
B S.E. C.R. P β SMC
Patient state → S-SDQ 1 0.749 .514
Patient state → NPI 4.770 0.475 10.036 *** 0.516 .308
Patient state → S-ADL 0.845 0.069 12.336 *** 0.624 .338
Patient state → S-IADL 1.914 0.127 15.071 *** 0.823 .332
Care activity → Time 1 0.576 .678
Care activity → Day 1.011 0.172 5.891 *** 0.581 .390
Care burden → ZBI 1 0.555 .266
Caregiver
depression → BDI 1 0.717 .561
***p<.001
As a result of checking the factor loading, it appeared that the factor loading values of all measurement variables composed of patient state, care activity, care burden, and depression were at least 0.516 or higher, which obtained validity. And the explanation power of each measurement variable, SMC(Squared Multiple Correlations) was at least .266, which appeared 26.6% or higher.
And the correlation between latent variables appeared like in <Table 6> below.
<Table 6> Correlation of latent variables
r
Patient state ↔ Care activity 0.504**
Patient state ↔ Care burden 0.658**
Patient state ↔ Caregiver depression 0.394**
Care activity ↔ Care burden 0.567**
Care activity ↔ Caregiver depression 0.252** Care burden ↔ Caregiver depression 0.876**
**p<.01
Patient state had a positive (+) correlation with all care activity, care burden, and depression. Care activity had a significant positive (+) correlation with care burden and depression. Care burden had a significant positive (+) correlation with depression.
