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The subjective burden of informal caregivers of persons with dementia: extended validation of the German language version of the Burden Scale for Family Caregivers (BSFC) a
a
b
H. Grau , E. Graessel & H. Berth a
Center of Health Services Research in Medicine, Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany b
Medical Psychology and Medical Sociology, Universitätsklinikum Carl Gustav Carus Dresden, Dresden, Germany Published online: 10 Jun 2014.
Click for updates To cite this article: H. Grau, E. Graessel & H. Berth (2015) The subjective burden of informal caregivers of persons with dementia: extended validation of the German language version of the Burden Scale for Family Caregivers (BSFC), Aging & Mental Health, 19:2, 159-168, DOI: 10.1080/13607863.2014.920296 To link to this article: http://dx.doi.org/10.1080/13607863.2014.920296
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Aging & Mental Health, 2015 Vol. 19, No. 2, 159 168, http://dx.doi.org/10.1080/13607863.2014.920296
The subjective burden of informal caregivers of persons with dementia: extended validation of the German language version of the Burden Scale for Family Caregivers (BSFC) H. Graua*, E. Graessela and H. Berthb a
Center of Health Services Research in Medicine, Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University atsklinikum Carl Gustav Carus Erlangen-N€ urnberg, Erlangen, Germany; bMedical Psychology and Medical Sociology, Universit€ Dresden, Dresden, Germany
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(Received 15 January 2014; accepted 21 April 2014) Objective: In research as well as in the practice of caregiver counselling, the subjective burden of family caregivers is considered an important characteristic of home care. The objective of the present study was to provide an extended validation of the German language version of the Burden Scale for Family Caregivers (BSFC) published in 2001. Methods: Extended validation was performed using medical, interview, and health insurance data of 351 informal caregivers and their relatives who had dementia. Cronbach’s alpha was calculated to assess the internal consistency of the items, and an exploratory factor analysis was conducted to determine the structure of the BSFC. The discriminatory power and item difficulties of the 28 BSFC items were examined. Five research questions addressed construct validity. Question six addressed the BSFC score as a potential predictor of institutionalization at a follow-up time of 2.5 years (predictive validity). Results: Exploratory factor analysis indicated that the BSFC had a single-factor structure. Cronbach’s alpha for the total scale was 0.93. A significant increase in the BSFC score was observed when the severity of cognitive impairment increased, persons with dementia showed disturbing behaviour, caregivers were diagnosed with depression, care requirements increased, or the family caregiver and the person with dementia lived together. Caregiver burden emerged as a significant predictor of institutionalization. The validity of the BSFC was confirmed by the results. Conclusion: The BSFC score allows for a valid assessment of the total caregiver burden in both research and practice. The BSFC is available for free in 20 languages (http://www.caregiver-burden.eu). Keywords: caregiver burden; Burden Scale for Family Caregivers; exploratory factor analysis; reliability; validity
Introduction Home care for chronically ill people imposes a high subjective and objective burden on family caregivers. Objective stress factors such as caregiving at night, disturbing behaviour of the person with dementia, or the management of anal and urinal incontinence form the basis of a caregiver stress model (Pearlin, Mullan, Semple, & Skaff, 1990). Research by Lazarus and Folkman (1984) suggests that an individual’s perception of stress is largely determined by cognitive processes such as the primary and secondary appraisal of one’s personal situation. From the perspective of caregivers, primary appraisal refers to the appraisal of various aspects of the experienced care situation. Secondary appraisal basically refers to the caregivers’ evaluation of their ability to cope with the care situation (Gr€aßel & Adabbo, 2011). The measurement of subjective burden with the Burden Scale for Family Caregivers (BSFC) (Gr€aßel, 2001) is based on such appraisal processes. The development of the BSFC was carried out in four steps. Across 12 sessions of two different support groups, a scientist used participant observation to record the aspects that were freely described (i.e. with no prompting) by family caregivers as a burden. In the second step, these narrations were converted into statements (items). To determine whether further aspects of burden needed to be *Corresponding author. Email: [email protected] Ó 2014 Taylor & Francis
added, these statements were compared with the items of three published burden scales in the third step (Kosberg, Cairl, & Keller, 1990; Robinson, 1983; Zarit, Reever, & Bach-Peterson, 1980). This matching with the international literature was carried out independently by two experts. When discrepancies occurred, consensus was developed. In the fourth step, the preliminary questionnaire was submitted to a group of family caregivers and feedback was obtained on the clarity of the individual items (pretest). The items were then put in their final form. The aim was to create a set of items that would represent all possible areas from which subjective burden derives. The spectrum extends from aspects of the family caregivers’ health (item three: ‘I often feel physically exhausted’) to their appraisals with regard to the person with dementia (item 27: ‘I feel sad because of the fate of the person I am caring for’). The questionnaire can be used in research and practice. The score is especially important in research. In practice, the counsellor can focus on the items with the maximum values to obtain a starting point for selective counselling. The great importance of the concept of subjective burden in research is mainly due to the significant association between subjective burden and four relevant outcome variables that pertain to the care situation. First: the higher the
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subjective burden, the more physical symptoms are reported (Gr€aßel, 1998). This applies only to caregivers who experience subjective burden. When comparing the total population of caregivers, without taking into account the different levels of burden, with non-caregivers of the same age group, there is no significant difference in the level of physical symptoms (Pinquart & S€ orensen, 2003). Second: spousal caregivers experiencing subjective burden show a significant increase in their mortality risk compared to non-caregivers of the same age group (Schulz & Beach, 1999). This applies only to caregivers who experience subjective burden. Caregivers who do not feel burdened by providing care are not subject to an increased mortality risk (Schulz & Beach, 1999). Third: abusive behaviour by caregivers toward the person with dementia becomes more likely when the burden on the caregiver is higher (Hansberry, Chen, & Gorbien, 2005; Yan & Kwok, 2011). Fourth: finally, subjective burden represents an important predictor of the institutionalization of persons with dementia (Gaugler, Leach, Clay, & Newcomer, 2004; Luppa, Luck, Braehler, Koenig, & Riedel-Heller, 2008; McCann et al., 2005; Yaffe et al., 2002). There are diverse concepts and, thus, operationalizations for the measurement of the subjective burden of family caregivers. Single-item scales (e.g. Kim & Schulz, 2008) tend to have a relatively low reliability compared to multi-item scales based on Cronbach’s alpha (Cronbach, 1951). Moreover, single-item scales are more susceptible to a social desirability response bias. Multi-item scales are categorized into scales with different subscores for specific dimensions (multi-factor concept; e.g. the five dimensions of the Cost of Care Index, Kosberg et al., 1990; Sense of Competence Questionnaire, Vernooij-Daasen, Peersoon, & Felling, 1996) and scales with a single score (single-factor concept; e.g. Zarit Burden Interview, Zarit et al., 1980; German language version, Braun, Scholz, Hornung, & Martin, 2010). The BSFC accurately satisfies the criterion of the single-factor score (Gr€aßel, 2001). Initial empirical validation was applied to a large sample and included comparison with the external criterion ‘extent of physical symptoms of the family caregiver’. Extended validation was indicated after one decade. The objective of the present study was to provide an extended validation of the German language version of the BSFC, initially released in 2001 (Gr€aßel, 2001). For the extended validation, we addressed more research questions than in the initial validation. In addition, a diagnosis of depression made by a psychiatrist or general practitioner was obtained as an external criterion of validity (construct validity), and an analysis to predict a future institutionalization was performed. All persons with dementia were living in their homes and not in long-term care. Methods Design of the original and the present study The original study was a three-armed cluster-randomized controlled trial (Dementia Care Initiative in Primary Practice Initiative Demenzversorgung in der
Allgemeinmedizin [‘IDA project’]) with the goal of evaluating a counselling programme for family caregivers (trial registration: ISRCTN68329593) (Holle et al., 2009). 390 persons with dementia and their family caregivers were recruited by general practitioners in the study region of Middle Franconia, Bavaria, Germany (Menn et al., 2012). Persons with dementia were included if they had a physician-diagnosed primary dementia (according to the ICD-10; World Health Organization [WHO], 2004) and a mild or moderate cognitive impairment (10 24 points; assessed with Mini-Mental State Examination [MMSE]; Folstein, Folstein, & McHugh, 1975), were at least 65 years old, and were members of the AOK Bavaria Health insurance. Persons in the end stage of life or who were not able or willing to provide informed consent were excluded. Study inclusion required the signed informed consent of persons and informal caregivers. The study was approved by the Ethics Committee at the Bavarian Chamber of Physicians (No. 05029) and is in accordance with the Helsinki Declaration. All data used in the present study were obtained from the original study’s baseline data. The exceptions are the data for the predictive validity of the BSFC (see research question Q6, chapter ‘Statistical Analysis/Validity’). These data included baseline data and data from the institutionalization event for the 2.5-year interval after baseline. Therefore the present study employed a secondary data analysis. Sample The current sample included 351 persons with dementia and their family caregivers and was obtained from an original sample that included 390 dyadic cases. All persons with dementia were living in their homes and not in long-term care. 357 caregivers completed the baseline telephone interview. There was no significant (p < 0.05) difference between the dropouts (n D 33) and the interviewed caregivers with regard to the available data delivered by the health insurer (care level of the person with dementia, depression diagnosis of the caregiver) and the general practitioners (characteristics of the persons with dementia). Caregivers were asked to maintain their consent throughout the duration of the study (n D 351). Twenty-five per cent of the participants were from cities with more than 100,000 citizens. The mean age of the family caregivers was 59.2 years (SD D 13.4), 73% were female, 31% were spouses, 60% were caregiving children/-in-law, and 9% were other informal caregivers (e.g. aunts, uncles, nieces, nephews). The mean age of the persons with dementia was 80.3 years (SD D 6.7), and 68% were female. Sixty-four per cent suffered from a mild form of dementia (MMSE: 18 24 points) (Folstein et al., 1975) and 36% from a moderate form (MMSE: 10 17 points). Instruments All instruments were administered in the German language.
Aging & Mental Health Burden Scale for Family Caregivers The BSFC (German language version: Gr€aßel, 2001; English language version: Gr€asel, Chiu, & Oliver, 2003) is a 28-item self-assessment scale for measuring caregiver burden. The items are rated on a scale from zero (‘strongly disagree’) to three (‘strongly agree’). The score ranges from zero to 84 points. Higher scores indicate greater caregiver burden. Mini-Mental State Examination The Mini-Mental State Examination (MMSE; Folstein et al., 1975) is used for dementia screening. The score ranges from zero to 30 points, with higher values indicating greater performance capacity.
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Nurses’ Observation Scale for Geriatric Patients The Nurses’ Observation Scale for Geriatric Patients (NOSGER; Spiegel et al., 1991) covers the most frequent aberrancies of geriatric patients in the form of an observer rating scale. For our study, the subscale ‘disturbing behavior’ was used. Higher score indicates greater impairment. The subscale consists of five items, rated on a scale from one (‘always’) to five (‘never’). The test-retest reliability is 0.84 (Wahle, H€aller, & Spiegel, 1996). Barthel Index The Barthel Index (BI; Mahoney & Barthel, 1965) is an observer rating scale, which is widely used internationally to rate independence in basic activities of daily life. Higher scores indicate greater independence. Basic everyday practical capabilities are rated in 10 areas at two to four levels (0, 5, 10, 15 points). The score ranges from zero (‘dependent in all areas’) to 100 points (‘completely independent’). The reliability using the intraclass correlation coefficient for elderly people is 0.89 (Sainsbury, Seebass, Bansal, & Young, 2005). Resource Utilization in Dementia The Resource Utilization in Dementia short version (RUD Lite; Wimo & Winblad, 2003) assesses informal care time, i.e. how many hours per day on average the primary informal caregiver provides services to the person with dementia. Informal care activities are divided into three categories: activities of daily living (ADL), instrumental activities of daily living (IADL), and supervision. While ADL includes activities such as toilet visits, bathing, and dressing, IADL comprises more complex activities such as shopping, food preparation, and housekeeping. Wimo and Nordberg (2007) tested the validity. It was good for the time measurement of ADL and supervision. We used the score for total care time. Other measures Depression diagnosis. The depression diagnosis was obtained from the health insurance data of the family caregivers. With regard to the feasibility of ‘the IDA
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project’, whose data form the basis of the present study, the availability of health insurance data was limited to family caregivers insured by the German health insurer AOK (168 of 351 caregivers; 48%). Presence of a diagnosis of depression was subject to the condition that the caregiver’s ‘depression’ was classified as depression according to the ICD-10 code (WHO, 2004) by psychiatrists or general practitioners at least in the quarters before and after the assessment of caregiver burden. Thus, the depression diagnosis is a variable that was generated independently of all other study data, including caregiver burden. Housing situation. Besides the socio-demographic data of the family caregiver and the person with dementia, the housing situation was also recorded, i.e. do the two share a flat or house or do they live separately? Nursing care needs (care level). Nursing care needs were determined based on the four-level scale used in Germany to establish eligibility for nursing care benefits. This information was retrieved from the persons’ long-term care insurance data. The persons’ nursing care needs were assessed by a qualified health care professional when the persons applied for long-term care insurance support. The care level describes the extent to which the person is eligible to receive assistance from long-term care insurance. The classification is based on the person’s need for physical care and ranges from none (level zero) to mild (level one) to moderate (level two) to great need for care (level three). For level three, a daily need for help of at least five hours is required. The time required is determined on the basis of standardized time corridors for certain activities. Caregiving tasks at night. We additionally recorded the average frequency with which caregiving tasks at night interrupted the sleep of family caregivers.
Data recording The general practitioners who did the recruiting collected the socio-demographic data of the persons with dementia and recorded the ICD-10 diagnosis code for primary dementia as well as the MMSE score. At baseline, trained interviewers conducted a computer-assisted telephone interview with the informal caregivers who were primarily responsible for home care. In addition to the sociodemographic data, the caregiver burden (BSFC), the NOSGER subscale ‘disturbing behavior’, as well as the BI and the RUD Lite were recorded. The depression diagnosis at baseline was obtained from the health insurance data of the family caregiver and made by a psychiatrist or general practitioner. The care level at baseline and the outcome of ‘institutionalization’ or ‘death’ at a follow-up time of 2.5 years were retrieved from the long-term health insurance data of patients with dementia.
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Statistical analysis Description and factor analysis The mean, median, standard deviation, and skewness of the BSFC score were calculated. To explore the underlying structure of the BSFC items, an exploratory factor analysis was performed. If more than one component with an eigenvalue greater than 1.0 was obtained (Kaiser criterion), orthogonal rotation was used to obtain a simple structure of variable grouping. The criterion for assigning a variable to a factor was defined as a factor loading 0.50.
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Reliability and item analysis Cronbach’s alpha was computed as a measure of internal consistency. For well-designed scales an alpha of 0.80 or higher is recommended by Bortz and D€ oring (2006). The difficulty index and discriminatory power were calculated at the item level. Because a four-step response format (zero to three points) is used for the BSFC items, the ratio of the sum of the squared subject’s P points to the sum of x2 the squared item maximum P x2 (Fisseni, 1997) was max
used to compute the difficulty index. Bortz and D€oring (2006) recommend a corridor from 0.20 to 0.80 for this index. Discriminatory power was calculated as the deleted item total correlation. According to Bortz and D€oring (2006), a discriminatory power of 0.30 0.50 is rated as moderate and a power of >0.50 as high. Validity The following research questions (Q) were addressed to assess construct validity (Q1 Q5) and predictive validity (Q6): Q1: How is the caregiver burden correlated with the severity of the cognitive impairment assessed by the MMSE? Q2: How is the caregiver burden associated with disturbing behaviours (operationalized using the NOSGER subscale ‘disturbing behavior’)? Q3: How is the caregiver burden associated with the mental health of family caregivers, i.e. family caregivers diagnosed with or without a ‘depressive episode’? Q4: How is the caregiver burden correlated with family caregivers who have only limited possibilities to retreat, i.e. caregivers sharing a flat/house with the person with dementia? Q5: How is caregiver burden associated with the care requirements, i.e. the care level, the degree of independence of the person with dementia (measured with the BI), the caregiving tasks must be performed at night, the average hours of daily support (assessed by the RUD Lite)? Q6: How is the caregiver burden correlated with a future institutionalization of the person with dementia?
To address Q1 Q5, the correlation between the BSFC score and metric variables was determined using Spearman’s rank correlation coefficient (rS), whereas eta was calculated to identify the correlation with nominally scaled variables. Differences in the median values were tested using the Mann Whitney or Kruskal Wallis test. Due to the left-skewed distribution of the BSFC score, non-parametric procedures were given priority here. All statistical procedures used two-tailed tests (p < 0.05 for significant results). The long-term health insurance data were used to determine which persons with dementia were institutionalized or had died at home at the follow-up time of 2.5 years. Thus, a predictive analysis of the outcome ‘institutionalization’, using the baseline data as potential predictors, was computed to test Q6. A binary logistic regression with ‘institutionalization’ (coded yes D 1 and no D 0) as the dependent variable was computed. For this, the outcome ‘death at home’ was eliminated. In a first step, bivariate analyses were computed for all independent variables to identify significant correlations (p < 0.05) with the dependent variable ‘institutionalization yes/no’. In a second step, a multicollinearity analysis was computed with all significant bivariate predictors to eliminate the confounding of predictors that were correlated with each other (with correlation coefficients 0.50). In a third step, all significant bivariate predictors that were not affected by multicollinearity were entered into the binary logistic regression model. The variance explained by the regression model was indicated by Nagelkerke’s R2. The significance of predictors was estimated using the Wald coefficient. Results Distribution of the BSFC score The distribution of the BSFC scores in the current study ranged from zero to 72 points (Figure 1). This observed range covered 90% of the theoretically available range of zero to 84 points. The variance of the BSFC score was 64.6, and the interquartile range was 25. Due to the high frequency of low scores the 25th percentile was 11 the distribution was right-skewed (skewness D 0.50). The median was 22, and the mean was 25.0 (SD D 17.0). Inter-correlations of the BSFC items The exploratory factor analysis revealed that the structure of the BSFC could be represented with one dominant factor. Four components had eigenvalues greater than 1.0 (Table 1). The dominant factor accounted for 37% of the total variance of the BSFC score; the other factors explained only 8%, 5%, or 4%, respectively. Nineteen items loaded highly (factor loading > 0.50) and three items loaded moderately (factor loading > 0.45) on the dominant factor. Item analysis and reliability The item difficulties of the BSFC items ranged from 0.06 to 0.51 (Table 2), and the mean item values (item range:
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Figure 1. Distribution of the BSFC score. Note: 25th percentile: 11, 50th percentile: 22, 75th percentile: 37.
zero to three) varied from 0.3 for ‘I feel like being forced into this caregiving situation’ (item 13) to 1.8 for ‘I feel sad because of the fate of the person I am caring for’ (item 27). The range from 1.9 to 3.0 was not observed. The discriminatory power ranged from 0.10 to 0.75 (Table 2). One item showed a weak discriminatory power of 0.10 (item 19: ‘It doesn’t bother me if outsiders are aware of the sick person’s situation’), 9 items had moderate discriminatory power between 0.29 and 0.48, and 18 items had high discriminatory power between 0.54 and 0.75. For 26 items, Cronbach’s alpha ‘if item deleted’ was below or equal to 0.932 for the complete scale (Table 2). Only two items had a Cronbach’s alpha ‘if item deleted’ greater than 0.932. These items were ‘The care I give is not acknowledged by others’ (item 11) and ‘It doesn’t bother me if outsiders are aware of the sick person’s situation’ (item 19).
Construct and predictive validity Caregiver burden increased significantly with the severity of the cognitive impairment of the person with dementia (MMSE; rS D ¡0.23; Table 3) or with the severity of the non-cognitive symptoms of the person with dementia (NOSGER subscale ‘disturbing behavior’; rS D 0.57).
Caregivers who had been diagnosed with depression (n D 30; 18%) scored higher on the BSFC than those without a diagnosis of depression (eta D 0.19). The caregiver’s level of subjective burden was higher when persons with dementia and caregivers shared a flat or house than when they lived separately (eta D 0.13). A significant increase in the BSFC score was observed when care requirements increased: care level (eta D 0.27), degree of dependence (BI; rS D ¡0.44), caregiving tasks at night (eta D 0.38), and informal caregiving hours per day (RUD Lite; rS D 0.53). Caregiver burden emerged as a predictor of the institutionalization of a person with dementia (Table 4). Furthermore, the rate of institutionalization was significantly higher for older and more cognitively impaired persons with dementia. The same applied when the caregivers did not share a flat or house with the persons with dementia. All reported correlations were statistically significant. The results of the research questions confirmed the construct and predictive validity of the BSFC.
Discussion The objective of this study was to provide an extended validation of the BSFC. The research questions addressed
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Table 1. Exploratory factor analysis of the BSFC score: factor loadings of the items on the four components with eigenvalues >1.0. Component n (eigenvalue)
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Item summary 1 Sleep deprivation 2 Reduced life satisfaction 3 Physical exhaustion 4 Wish to run away 5 Communication deficit 6 Not enough time for my own interests 7 Feeling of being used 8 Not being able to switch off 9 Difficulties providing care 10 Depersonalization 11 Care not adequately acknowledged 12 Decreased standard of living 13 Forced into caregiving situation 14 Unreasonable wishes of care-receiver 15 Not having a handle on the caregiving 16 Health affected by caregiving 17 Incapable of feeling joyful 18 Giving up future plans 19 Bothered by outsiders 20 Caregiving is taking strength 21 Conflicting demands 22 Relationship with care-receiver getting worse 23 Problems with the family 24 Wish to take a break 25 Worried about the future 26 Relationships with others are suffering 27 Sadness about the fate of the care-receiver 28 Fulfilment of other obligations is difficult
#1 (10.28)
#2 (2.19)
#3 (1.26)
#4 (1.14)
0.60 0.80 0.76 0.73 0.47 0.67 0.58 0.68 0.51 0.72 0.34 0.75 0.31 0.45 0.47 0.76 0.61 0.60 0.11 0.73 0.78 0.46 0.41 0.68 0.61 0.64 0.46 0.68
¡0.19 ¡0.11 ¡0.25 ¡0.05 0.05 ¡0.23 0.25 ¡0.07 0.32 ¡0.12 0.38 ¡0.27 0.57 0.54 0.45 ¡0.17 ¡0.11 ¡0.14 0.18 ¡0.32 0.08 0.57 0.40 ¡0.14 0.09 0.08 ¡0.30 ¡0.06
¡0.16 ¡0.14 ¡0.17 ¡0.05 0.24 0.00 ¡0.12 ¡0.08 ¡0.41 ¡0.04 0.30 0.11 0.23 ¡0.19 ¡0.23 ¡0.08 ¡0.15 0.28 ¡0.33 ¡0.06 0.05 ¡0.23 0.48 0.09 0.30 0.28 ¡0.07 0.10
¡0.10 ¡0.02 ¡0.21 ¡0.32 0.12 0.12 ¡0.39 0.25 0.06 ¡0.10 0.24 ¡0.01 ¡0.24 0.06 0.19 ¡0.09 0.25 0.06 0.51 ¡0.12 ¡0.06 ¡0.18 0.02 ¡0.13 0.01 0.16 0.27 0.28
how the caregiver burden was correlated with each of the other aspects that were explored. These included cognitive and non-cognitive symptoms of dementia (MMSE, NOSGER subscale ‘disturbing behavior’), the psychological health of the caregiver (depression diagnosis), social aspects of the living situation (living together/separately), care requirements (care level, degree of dependence, caregiving tasks at night, informal caregiving time), and future institutionalization. The results make it possible to gain a more differentiated insight into the importance of the concept of subjective caregiver burden. First, we want to discuss the structure of the BSFC and the characteristics of the items. The results of the exploratory factor analysis confirmed that the BSFC score summarizing all 28 item values and operationalizing total caregiver burden was empirically justified. Factor one, which comprised 22 of the 28 items with factor loadings greater than 0.45, had an eigenvalue five times that of factor two. Caregiver burden measured with the BSFC showed high inter-individual variability on the score level as well as on the item level. The exclusion of severe cases of dementia had a relevant effect on the difficulty index of the BSFC items. This is the reason why only 9 of 28 items
had a difficulty index greater than 0.25. Simultaneously considering discriminatory power and Cronbach’s alpha ‘if item deleted’, satisfactory values were derived for 27 of 28 items. Only item 19 ‘It doesn’t bother me if outsiders are aware of the sick person’s situation’ was the odd one out. This item was only rarely associated with the caregiver’s level of burden, and its correlation with the scores of the remaining 27 items was low. However, because of the importance of the content of this item, which refers to the caregiver’s risk of social isolation, it would not be acceptable to eliminate this item. Second, the main results of the validity analysis are considered with regard to the recent state of research. The degree to which persons with dementia exhibited disturbing behaviour was most strongly associated with the caregiver’s level of burden. This finding is consistent with the literature (Black & Almeida, 2004; Clyburn, Stones, Hadjistavropoulos, & Tuokko, 2000; Machida, 2012; Perren, Schmid, & Wettstein, 2006), which confirms that disturbing behaviour considerably contributes to the caregiver’s burden. The relation between subjective burden and a diagnosis of depression in caregivers has not yet been examined. It is known that scores on self-rated depression scales
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Table 2. Characteristics of the items of the BSFC. Item summary
Mean (SDa)
1 Sleep deprivation 2 Reduced life satisfaction 3 Physical exhaustion 4 Wish to run away 5 Communication deficit 6 Not enough time for my own interests 7 Feeling of being used 8 Not being able to switch off 9 Difficulties providing care 10 Depersonalization 11 Care not adequately acknowledged 12 Decreased standard of living 13 Forced into caregiving situation 14 Unreasonable wishes of care-receiver 15 Not having a handle on the caregiving 16 Health affected by caregiving 17 Incapable of feeling joyful 18 Giving up future plans 19 Bothered by outsiders 20 Caregiving is taking strength 21 Conflicting demands 22 Relationship with care-receiver getting worse 23 Problems with the family 24 Wish to take a break 25 Worried about the future 26 Relationships with others are suffering 27 Sadness about the fate of the care-receiver 28 Fulfilment of other obligations is difficult
1.3 (1.0) 1.1 (1.0) 1.3 (1.1) 1.1 (1.1) 0.5 (0.9) 1.4 (1.1) 0.6 (0.9) 1.2 (1.1) 0.8 (1.0) 0.7 (1.0) 1.0 (1.1) 1.2 (1.2) 0.3 (0.7) 0.6 (0.9) 0.6 (0.8) 0.9 (1.0) 0.7 (1.0) 0.9 (1.1) 0.4 (0.8) 1.5 (1.1) 1.1 (1.1) 0.4 (0.7) 0.5 (0.9) 1.6 (1.2) 0.8 (1.1) 0.7 (1.0) 1.8 (1.2) 1.0 (1.0)
Item difficulty
Discriminatory power
Pb
Cronbach’s alpha ‘if item deleted’c
0.29 0.24 0.32 0.26 0.13 0.35 0.14 0.28 0.18 0.16 0.25 0.30 0.06 0.13 0.10 0.21 0.17 0.21 0.09 0.39 0.26 0.07 0.11 0.43 0.19 0.17 0.51 0.23
0.55 0.75 0.71 0.68 0.44 0.62 0.54 0.64 0.48 0.68 0.32 0.71 0.29 0.42 0.44 0.72 0.57 0.55 0.10 0.68 0.75 0.43 0.39 0.63 0.57 0.60 0.41 0.65
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The subjective burden of informal caregivers of persons with dementia: extended validation of the German language version of the Burden Scale for Family Caregivers (BSFC) a
a
b
H. Grau , E. Graessel & H. Berth a
Center of Health Services Research in Medicine, Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany b
Medical Psychology and Medical Sociology, Universitätsklinikum Carl Gustav Carus Dresden, Dresden, Germany Published online: 10 Jun 2014.
Click for updates To cite this article: H. Grau, E. Graessel & H. Berth (2015) The subjective burden of informal caregivers of persons with dementia: extended validation of the German language version of the Burden Scale for Family Caregivers (BSFC), Aging & Mental Health, 19:2, 159-168, DOI: 10.1080/13607863.2014.920296 To link to this article: http://dx.doi.org/10.1080/13607863.2014.920296
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Aging & Mental Health, 2015 Vol. 19, No. 2, 159 168, http://dx.doi.org/10.1080/13607863.2014.920296
The subjective burden of informal caregivers of persons with dementia: extended validation of the German language version of the Burden Scale for Family Caregivers (BSFC) H. Graua*, E. Graessela and H. Berthb a
Center of Health Services Research in Medicine, Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University atsklinikum Carl Gustav Carus Erlangen-N€ urnberg, Erlangen, Germany; bMedical Psychology and Medical Sociology, Universit€ Dresden, Dresden, Germany
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(Received 15 January 2014; accepted 21 April 2014) Objective: In research as well as in the practice of caregiver counselling, the subjective burden of family caregivers is considered an important characteristic of home care. The objective of the present study was to provide an extended validation of the German language version of the Burden Scale for Family Caregivers (BSFC) published in 2001. Methods: Extended validation was performed using medical, interview, and health insurance data of 351 informal caregivers and their relatives who had dementia. Cronbach’s alpha was calculated to assess the internal consistency of the items, and an exploratory factor analysis was conducted to determine the structure of the BSFC. The discriminatory power and item difficulties of the 28 BSFC items were examined. Five research questions addressed construct validity. Question six addressed the BSFC score as a potential predictor of institutionalization at a follow-up time of 2.5 years (predictive validity). Results: Exploratory factor analysis indicated that the BSFC had a single-factor structure. Cronbach’s alpha for the total scale was 0.93. A significant increase in the BSFC score was observed when the severity of cognitive impairment increased, persons with dementia showed disturbing behaviour, caregivers were diagnosed with depression, care requirements increased, or the family caregiver and the person with dementia lived together. Caregiver burden emerged as a significant predictor of institutionalization. The validity of the BSFC was confirmed by the results. Conclusion: The BSFC score allows for a valid assessment of the total caregiver burden in both research and practice. The BSFC is available for free in 20 languages (http://www.caregiver-burden.eu). Keywords: caregiver burden; Burden Scale for Family Caregivers; exploratory factor analysis; reliability; validity
Introduction Home care for chronically ill people imposes a high subjective and objective burden on family caregivers. Objective stress factors such as caregiving at night, disturbing behaviour of the person with dementia, or the management of anal and urinal incontinence form the basis of a caregiver stress model (Pearlin, Mullan, Semple, & Skaff, 1990). Research by Lazarus and Folkman (1984) suggests that an individual’s perception of stress is largely determined by cognitive processes such as the primary and secondary appraisal of one’s personal situation. From the perspective of caregivers, primary appraisal refers to the appraisal of various aspects of the experienced care situation. Secondary appraisal basically refers to the caregivers’ evaluation of their ability to cope with the care situation (Gr€aßel & Adabbo, 2011). The measurement of subjective burden with the Burden Scale for Family Caregivers (BSFC) (Gr€aßel, 2001) is based on such appraisal processes. The development of the BSFC was carried out in four steps. Across 12 sessions of two different support groups, a scientist used participant observation to record the aspects that were freely described (i.e. with no prompting) by family caregivers as a burden. In the second step, these narrations were converted into statements (items). To determine whether further aspects of burden needed to be *Corresponding author. Email: [email protected] Ó 2014 Taylor & Francis
added, these statements were compared with the items of three published burden scales in the third step (Kosberg, Cairl, & Keller, 1990; Robinson, 1983; Zarit, Reever, & Bach-Peterson, 1980). This matching with the international literature was carried out independently by two experts. When discrepancies occurred, consensus was developed. In the fourth step, the preliminary questionnaire was submitted to a group of family caregivers and feedback was obtained on the clarity of the individual items (pretest). The items were then put in their final form. The aim was to create a set of items that would represent all possible areas from which subjective burden derives. The spectrum extends from aspects of the family caregivers’ health (item three: ‘I often feel physically exhausted’) to their appraisals with regard to the person with dementia (item 27: ‘I feel sad because of the fate of the person I am caring for’). The questionnaire can be used in research and practice. The score is especially important in research. In practice, the counsellor can focus on the items with the maximum values to obtain a starting point for selective counselling. The great importance of the concept of subjective burden in research is mainly due to the significant association between subjective burden and four relevant outcome variables that pertain to the care situation. First: the higher the
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subjective burden, the more physical symptoms are reported (Gr€aßel, 1998). This applies only to caregivers who experience subjective burden. When comparing the total population of caregivers, without taking into account the different levels of burden, with non-caregivers of the same age group, there is no significant difference in the level of physical symptoms (Pinquart & S€ orensen, 2003). Second: spousal caregivers experiencing subjective burden show a significant increase in their mortality risk compared to non-caregivers of the same age group (Schulz & Beach, 1999). This applies only to caregivers who experience subjective burden. Caregivers who do not feel burdened by providing care are not subject to an increased mortality risk (Schulz & Beach, 1999). Third: abusive behaviour by caregivers toward the person with dementia becomes more likely when the burden on the caregiver is higher (Hansberry, Chen, & Gorbien, 2005; Yan & Kwok, 2011). Fourth: finally, subjective burden represents an important predictor of the institutionalization of persons with dementia (Gaugler, Leach, Clay, & Newcomer, 2004; Luppa, Luck, Braehler, Koenig, & Riedel-Heller, 2008; McCann et al., 2005; Yaffe et al., 2002). There are diverse concepts and, thus, operationalizations for the measurement of the subjective burden of family caregivers. Single-item scales (e.g. Kim & Schulz, 2008) tend to have a relatively low reliability compared to multi-item scales based on Cronbach’s alpha (Cronbach, 1951). Moreover, single-item scales are more susceptible to a social desirability response bias. Multi-item scales are categorized into scales with different subscores for specific dimensions (multi-factor concept; e.g. the five dimensions of the Cost of Care Index, Kosberg et al., 1990; Sense of Competence Questionnaire, Vernooij-Daasen, Peersoon, & Felling, 1996) and scales with a single score (single-factor concept; e.g. Zarit Burden Interview, Zarit et al., 1980; German language version, Braun, Scholz, Hornung, & Martin, 2010). The BSFC accurately satisfies the criterion of the single-factor score (Gr€aßel, 2001). Initial empirical validation was applied to a large sample and included comparison with the external criterion ‘extent of physical symptoms of the family caregiver’. Extended validation was indicated after one decade. The objective of the present study was to provide an extended validation of the German language version of the BSFC, initially released in 2001 (Gr€aßel, 2001). For the extended validation, we addressed more research questions than in the initial validation. In addition, a diagnosis of depression made by a psychiatrist or general practitioner was obtained as an external criterion of validity (construct validity), and an analysis to predict a future institutionalization was performed. All persons with dementia were living in their homes and not in long-term care. Methods Design of the original and the present study The original study was a three-armed cluster-randomized controlled trial (Dementia Care Initiative in Primary Practice Initiative Demenzversorgung in der
Allgemeinmedizin [‘IDA project’]) with the goal of evaluating a counselling programme for family caregivers (trial registration: ISRCTN68329593) (Holle et al., 2009). 390 persons with dementia and their family caregivers were recruited by general practitioners in the study region of Middle Franconia, Bavaria, Germany (Menn et al., 2012). Persons with dementia were included if they had a physician-diagnosed primary dementia (according to the ICD-10; World Health Organization [WHO], 2004) and a mild or moderate cognitive impairment (10 24 points; assessed with Mini-Mental State Examination [MMSE]; Folstein, Folstein, & McHugh, 1975), were at least 65 years old, and were members of the AOK Bavaria Health insurance. Persons in the end stage of life or who were not able or willing to provide informed consent were excluded. Study inclusion required the signed informed consent of persons and informal caregivers. The study was approved by the Ethics Committee at the Bavarian Chamber of Physicians (No. 05029) and is in accordance with the Helsinki Declaration. All data used in the present study were obtained from the original study’s baseline data. The exceptions are the data for the predictive validity of the BSFC (see research question Q6, chapter ‘Statistical Analysis/Validity’). These data included baseline data and data from the institutionalization event for the 2.5-year interval after baseline. Therefore the present study employed a secondary data analysis. Sample The current sample included 351 persons with dementia and their family caregivers and was obtained from an original sample that included 390 dyadic cases. All persons with dementia were living in their homes and not in long-term care. 357 caregivers completed the baseline telephone interview. There was no significant (p < 0.05) difference between the dropouts (n D 33) and the interviewed caregivers with regard to the available data delivered by the health insurer (care level of the person with dementia, depression diagnosis of the caregiver) and the general practitioners (characteristics of the persons with dementia). Caregivers were asked to maintain their consent throughout the duration of the study (n D 351). Twenty-five per cent of the participants were from cities with more than 100,000 citizens. The mean age of the family caregivers was 59.2 years (SD D 13.4), 73% were female, 31% were spouses, 60% were caregiving children/-in-law, and 9% were other informal caregivers (e.g. aunts, uncles, nieces, nephews). The mean age of the persons with dementia was 80.3 years (SD D 6.7), and 68% were female. Sixty-four per cent suffered from a mild form of dementia (MMSE: 18 24 points) (Folstein et al., 1975) and 36% from a moderate form (MMSE: 10 17 points). Instruments All instruments were administered in the German language.
Aging & Mental Health Burden Scale for Family Caregivers The BSFC (German language version: Gr€aßel, 2001; English language version: Gr€asel, Chiu, & Oliver, 2003) is a 28-item self-assessment scale for measuring caregiver burden. The items are rated on a scale from zero (‘strongly disagree’) to three (‘strongly agree’). The score ranges from zero to 84 points. Higher scores indicate greater caregiver burden. Mini-Mental State Examination The Mini-Mental State Examination (MMSE; Folstein et al., 1975) is used for dementia screening. The score ranges from zero to 30 points, with higher values indicating greater performance capacity.
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Nurses’ Observation Scale for Geriatric Patients The Nurses’ Observation Scale for Geriatric Patients (NOSGER; Spiegel et al., 1991) covers the most frequent aberrancies of geriatric patients in the form of an observer rating scale. For our study, the subscale ‘disturbing behavior’ was used. Higher score indicates greater impairment. The subscale consists of five items, rated on a scale from one (‘always’) to five (‘never’). The test-retest reliability is 0.84 (Wahle, H€aller, & Spiegel, 1996). Barthel Index The Barthel Index (BI; Mahoney & Barthel, 1965) is an observer rating scale, which is widely used internationally to rate independence in basic activities of daily life. Higher scores indicate greater independence. Basic everyday practical capabilities are rated in 10 areas at two to four levels (0, 5, 10, 15 points). The score ranges from zero (‘dependent in all areas’) to 100 points (‘completely independent’). The reliability using the intraclass correlation coefficient for elderly people is 0.89 (Sainsbury, Seebass, Bansal, & Young, 2005). Resource Utilization in Dementia The Resource Utilization in Dementia short version (RUD Lite; Wimo & Winblad, 2003) assesses informal care time, i.e. how many hours per day on average the primary informal caregiver provides services to the person with dementia. Informal care activities are divided into three categories: activities of daily living (ADL), instrumental activities of daily living (IADL), and supervision. While ADL includes activities such as toilet visits, bathing, and dressing, IADL comprises more complex activities such as shopping, food preparation, and housekeeping. Wimo and Nordberg (2007) tested the validity. It was good for the time measurement of ADL and supervision. We used the score for total care time. Other measures Depression diagnosis. The depression diagnosis was obtained from the health insurance data of the family caregivers. With regard to the feasibility of ‘the IDA
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project’, whose data form the basis of the present study, the availability of health insurance data was limited to family caregivers insured by the German health insurer AOK (168 of 351 caregivers; 48%). Presence of a diagnosis of depression was subject to the condition that the caregiver’s ‘depression’ was classified as depression according to the ICD-10 code (WHO, 2004) by psychiatrists or general practitioners at least in the quarters before and after the assessment of caregiver burden. Thus, the depression diagnosis is a variable that was generated independently of all other study data, including caregiver burden. Housing situation. Besides the socio-demographic data of the family caregiver and the person with dementia, the housing situation was also recorded, i.e. do the two share a flat or house or do they live separately? Nursing care needs (care level). Nursing care needs were determined based on the four-level scale used in Germany to establish eligibility for nursing care benefits. This information was retrieved from the persons’ long-term care insurance data. The persons’ nursing care needs were assessed by a qualified health care professional when the persons applied for long-term care insurance support. The care level describes the extent to which the person is eligible to receive assistance from long-term care insurance. The classification is based on the person’s need for physical care and ranges from none (level zero) to mild (level one) to moderate (level two) to great need for care (level three). For level three, a daily need for help of at least five hours is required. The time required is determined on the basis of standardized time corridors for certain activities. Caregiving tasks at night. We additionally recorded the average frequency with which caregiving tasks at night interrupted the sleep of family caregivers.
Data recording The general practitioners who did the recruiting collected the socio-demographic data of the persons with dementia and recorded the ICD-10 diagnosis code for primary dementia as well as the MMSE score. At baseline, trained interviewers conducted a computer-assisted telephone interview with the informal caregivers who were primarily responsible for home care. In addition to the sociodemographic data, the caregiver burden (BSFC), the NOSGER subscale ‘disturbing behavior’, as well as the BI and the RUD Lite were recorded. The depression diagnosis at baseline was obtained from the health insurance data of the family caregiver and made by a psychiatrist or general practitioner. The care level at baseline and the outcome of ‘institutionalization’ or ‘death’ at a follow-up time of 2.5 years were retrieved from the long-term health insurance data of patients with dementia.
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Statistical analysis Description and factor analysis The mean, median, standard deviation, and skewness of the BSFC score were calculated. To explore the underlying structure of the BSFC items, an exploratory factor analysis was performed. If more than one component with an eigenvalue greater than 1.0 was obtained (Kaiser criterion), orthogonal rotation was used to obtain a simple structure of variable grouping. The criterion for assigning a variable to a factor was defined as a factor loading 0.50.
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Reliability and item analysis Cronbach’s alpha was computed as a measure of internal consistency. For well-designed scales an alpha of 0.80 or higher is recommended by Bortz and D€ oring (2006). The difficulty index and discriminatory power were calculated at the item level. Because a four-step response format (zero to three points) is used for the BSFC items, the ratio of the sum of the squared subject’s P points to the sum of x2 the squared item maximum P x2 (Fisseni, 1997) was max
used to compute the difficulty index. Bortz and D€oring (2006) recommend a corridor from 0.20 to 0.80 for this index. Discriminatory power was calculated as the deleted item total correlation. According to Bortz and D€oring (2006), a discriminatory power of 0.30 0.50 is rated as moderate and a power of >0.50 as high. Validity The following research questions (Q) were addressed to assess construct validity (Q1 Q5) and predictive validity (Q6): Q1: How is the caregiver burden correlated with the severity of the cognitive impairment assessed by the MMSE? Q2: How is the caregiver burden associated with disturbing behaviours (operationalized using the NOSGER subscale ‘disturbing behavior’)? Q3: How is the caregiver burden associated with the mental health of family caregivers, i.e. family caregivers diagnosed with or without a ‘depressive episode’? Q4: How is the caregiver burden correlated with family caregivers who have only limited possibilities to retreat, i.e. caregivers sharing a flat/house with the person with dementia? Q5: How is caregiver burden associated with the care requirements, i.e. the care level, the degree of independence of the person with dementia (measured with the BI), the caregiving tasks must be performed at night, the average hours of daily support (assessed by the RUD Lite)? Q6: How is the caregiver burden correlated with a future institutionalization of the person with dementia?
To address Q1 Q5, the correlation between the BSFC score and metric variables was determined using Spearman’s rank correlation coefficient (rS), whereas eta was calculated to identify the correlation with nominally scaled variables. Differences in the median values were tested using the Mann Whitney or Kruskal Wallis test. Due to the left-skewed distribution of the BSFC score, non-parametric procedures were given priority here. All statistical procedures used two-tailed tests (p < 0.05 for significant results). The long-term health insurance data were used to determine which persons with dementia were institutionalized or had died at home at the follow-up time of 2.5 years. Thus, a predictive analysis of the outcome ‘institutionalization’, using the baseline data as potential predictors, was computed to test Q6. A binary logistic regression with ‘institutionalization’ (coded yes D 1 and no D 0) as the dependent variable was computed. For this, the outcome ‘death at home’ was eliminated. In a first step, bivariate analyses were computed for all independent variables to identify significant correlations (p < 0.05) with the dependent variable ‘institutionalization yes/no’. In a second step, a multicollinearity analysis was computed with all significant bivariate predictors to eliminate the confounding of predictors that were correlated with each other (with correlation coefficients 0.50). In a third step, all significant bivariate predictors that were not affected by multicollinearity were entered into the binary logistic regression model. The variance explained by the regression model was indicated by Nagelkerke’s R2. The significance of predictors was estimated using the Wald coefficient. Results Distribution of the BSFC score The distribution of the BSFC scores in the current study ranged from zero to 72 points (Figure 1). This observed range covered 90% of the theoretically available range of zero to 84 points. The variance of the BSFC score was 64.6, and the interquartile range was 25. Due to the high frequency of low scores the 25th percentile was 11 the distribution was right-skewed (skewness D 0.50). The median was 22, and the mean was 25.0 (SD D 17.0). Inter-correlations of the BSFC items The exploratory factor analysis revealed that the structure of the BSFC could be represented with one dominant factor. Four components had eigenvalues greater than 1.0 (Table 1). The dominant factor accounted for 37% of the total variance of the BSFC score; the other factors explained only 8%, 5%, or 4%, respectively. Nineteen items loaded highly (factor loading > 0.50) and three items loaded moderately (factor loading > 0.45) on the dominant factor. Item analysis and reliability The item difficulties of the BSFC items ranged from 0.06 to 0.51 (Table 2), and the mean item values (item range:
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Figure 1. Distribution of the BSFC score. Note: 25th percentile: 11, 50th percentile: 22, 75th percentile: 37.
zero to three) varied from 0.3 for ‘I feel like being forced into this caregiving situation’ (item 13) to 1.8 for ‘I feel sad because of the fate of the person I am caring for’ (item 27). The range from 1.9 to 3.0 was not observed. The discriminatory power ranged from 0.10 to 0.75 (Table 2). One item showed a weak discriminatory power of 0.10 (item 19: ‘It doesn’t bother me if outsiders are aware of the sick person’s situation’), 9 items had moderate discriminatory power between 0.29 and 0.48, and 18 items had high discriminatory power between 0.54 and 0.75. For 26 items, Cronbach’s alpha ‘if item deleted’ was below or equal to 0.932 for the complete scale (Table 2). Only two items had a Cronbach’s alpha ‘if item deleted’ greater than 0.932. These items were ‘The care I give is not acknowledged by others’ (item 11) and ‘It doesn’t bother me if outsiders are aware of the sick person’s situation’ (item 19).
Construct and predictive validity Caregiver burden increased significantly with the severity of the cognitive impairment of the person with dementia (MMSE; rS D ¡0.23; Table 3) or with the severity of the non-cognitive symptoms of the person with dementia (NOSGER subscale ‘disturbing behavior’; rS D 0.57).
Caregivers who had been diagnosed with depression (n D 30; 18%) scored higher on the BSFC than those without a diagnosis of depression (eta D 0.19). The caregiver’s level of subjective burden was higher when persons with dementia and caregivers shared a flat or house than when they lived separately (eta D 0.13). A significant increase in the BSFC score was observed when care requirements increased: care level (eta D 0.27), degree of dependence (BI; rS D ¡0.44), caregiving tasks at night (eta D 0.38), and informal caregiving hours per day (RUD Lite; rS D 0.53). Caregiver burden emerged as a predictor of the institutionalization of a person with dementia (Table 4). Furthermore, the rate of institutionalization was significantly higher for older and more cognitively impaired persons with dementia. The same applied when the caregivers did not share a flat or house with the persons with dementia. All reported correlations were statistically significant. The results of the research questions confirmed the construct and predictive validity of the BSFC.
Discussion The objective of this study was to provide an extended validation of the BSFC. The research questions addressed
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Table 1. Exploratory factor analysis of the BSFC score: factor loadings of the items on the four components with eigenvalues >1.0. Component n (eigenvalue)
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Item summary 1 Sleep deprivation 2 Reduced life satisfaction 3 Physical exhaustion 4 Wish to run away 5 Communication deficit 6 Not enough time for my own interests 7 Feeling of being used 8 Not being able to switch off 9 Difficulties providing care 10 Depersonalization 11 Care not adequately acknowledged 12 Decreased standard of living 13 Forced into caregiving situation 14 Unreasonable wishes of care-receiver 15 Not having a handle on the caregiving 16 Health affected by caregiving 17 Incapable of feeling joyful 18 Giving up future plans 19 Bothered by outsiders 20 Caregiving is taking strength 21 Conflicting demands 22 Relationship with care-receiver getting worse 23 Problems with the family 24 Wish to take a break 25 Worried about the future 26 Relationships with others are suffering 27 Sadness about the fate of the care-receiver 28 Fulfilment of other obligations is difficult
#1 (10.28)
#2 (2.19)
#3 (1.26)
#4 (1.14)
0.60 0.80 0.76 0.73 0.47 0.67 0.58 0.68 0.51 0.72 0.34 0.75 0.31 0.45 0.47 0.76 0.61 0.60 0.11 0.73 0.78 0.46 0.41 0.68 0.61 0.64 0.46 0.68
¡0.19 ¡0.11 ¡0.25 ¡0.05 0.05 ¡0.23 0.25 ¡0.07 0.32 ¡0.12 0.38 ¡0.27 0.57 0.54 0.45 ¡0.17 ¡0.11 ¡0.14 0.18 ¡0.32 0.08 0.57 0.40 ¡0.14 0.09 0.08 ¡0.30 ¡0.06
¡0.16 ¡0.14 ¡0.17 ¡0.05 0.24 0.00 ¡0.12 ¡0.08 ¡0.41 ¡0.04 0.30 0.11 0.23 ¡0.19 ¡0.23 ¡0.08 ¡0.15 0.28 ¡0.33 ¡0.06 0.05 ¡0.23 0.48 0.09 0.30 0.28 ¡0.07 0.10
¡0.10 ¡0.02 ¡0.21 ¡0.32 0.12 0.12 ¡0.39 0.25 0.06 ¡0.10 0.24 ¡0.01 ¡0.24 0.06 0.19 ¡0.09 0.25 0.06 0.51 ¡0.12 ¡0.06 ¡0.18 0.02 ¡0.13 0.01 0.16 0.27 0.28
how the caregiver burden was correlated with each of the other aspects that were explored. These included cognitive and non-cognitive symptoms of dementia (MMSE, NOSGER subscale ‘disturbing behavior’), the psychological health of the caregiver (depression diagnosis), social aspects of the living situation (living together/separately), care requirements (care level, degree of dependence, caregiving tasks at night, informal caregiving time), and future institutionalization. The results make it possible to gain a more differentiated insight into the importance of the concept of subjective caregiver burden. First, we want to discuss the structure of the BSFC and the characteristics of the items. The results of the exploratory factor analysis confirmed that the BSFC score summarizing all 28 item values and operationalizing total caregiver burden was empirically justified. Factor one, which comprised 22 of the 28 items with factor loadings greater than 0.45, had an eigenvalue five times that of factor two. Caregiver burden measured with the BSFC showed high inter-individual variability on the score level as well as on the item level. The exclusion of severe cases of dementia had a relevant effect on the difficulty index of the BSFC items. This is the reason why only 9 of 28 items
had a difficulty index greater than 0.25. Simultaneously considering discriminatory power and Cronbach’s alpha ‘if item deleted’, satisfactory values were derived for 27 of 28 items. Only item 19 ‘It doesn’t bother me if outsiders are aware of the sick person’s situation’ was the odd one out. This item was only rarely associated with the caregiver’s level of burden, and its correlation with the scores of the remaining 27 items was low. However, because of the importance of the content of this item, which refers to the caregiver’s risk of social isolation, it would not be acceptable to eliminate this item. Second, the main results of the validity analysis are considered with regard to the recent state of research. The degree to which persons with dementia exhibited disturbing behaviour was most strongly associated with the caregiver’s level of burden. This finding is consistent with the literature (Black & Almeida, 2004; Clyburn, Stones, Hadjistavropoulos, & Tuokko, 2000; Machida, 2012; Perren, Schmid, & Wettstein, 2006), which confirms that disturbing behaviour considerably contributes to the caregiver’s burden. The relation between subjective burden and a diagnosis of depression in caregivers has not yet been examined. It is known that scores on self-rated depression scales
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Table 2. Characteristics of the items of the BSFC. Item summary
Mean (SDa)
1 Sleep deprivation 2 Reduced life satisfaction 3 Physical exhaustion 4 Wish to run away 5 Communication deficit 6 Not enough time for my own interests 7 Feeling of being used 8 Not being able to switch off 9 Difficulties providing care 10 Depersonalization 11 Care not adequately acknowledged 12 Decreased standard of living 13 Forced into caregiving situation 14 Unreasonable wishes of care-receiver 15 Not having a handle on the caregiving 16 Health affected by caregiving 17 Incapable of feeling joyful 18 Giving up future plans 19 Bothered by outsiders 20 Caregiving is taking strength 21 Conflicting demands 22 Relationship with care-receiver getting worse 23 Problems with the family 24 Wish to take a break 25 Worried about the future 26 Relationships with others are suffering 27 Sadness about the fate of the care-receiver 28 Fulfilment of other obligations is difficult
1.3 (1.0) 1.1 (1.0) 1.3 (1.1) 1.1 (1.1) 0.5 (0.9) 1.4 (1.1) 0.6 (0.9) 1.2 (1.1) 0.8 (1.0) 0.7 (1.0) 1.0 (1.1) 1.2 (1.2) 0.3 (0.7) 0.6 (0.9) 0.6 (0.8) 0.9 (1.0) 0.7 (1.0) 0.9 (1.1) 0.4 (0.8) 1.5 (1.1) 1.1 (1.1) 0.4 (0.7) 0.5 (0.9) 1.6 (1.2) 0.8 (1.1) 0.7 (1.0) 1.8 (1.2) 1.0 (1.0)
Item difficulty
Discriminatory power
Pb
Cronbach’s alpha ‘if item deleted’c
0.29 0.24 0.32 0.26 0.13 0.35 0.14 0.28 0.18 0.16 0.25 0.30 0.06 0.13 0.10 0.21 0.17 0.21 0.09 0.39 0.26 0.07 0.11 0.43 0.19 0.17 0.51 0.23
0.55 0.75 0.71 0.68 0.44 0.62 0.54 0.64 0.48 0.68 0.32 0.71 0.29 0.42 0.44 0.72 0.57 0.55 0.10 0.68 0.75 0.43 0.39 0.63 0.57 0.60 0.41 0.65
