Aging & Mental Health
ISSN: 1360-7863 (Print) 1364-6915 (Online) Journal homepage: http://www.tandfonline.com/loi/camh20
Validating a Cantonese short version of the Zarit Burden Interview (CZBI-Short) for dementia caregivers Jennifer Yee-man Tang, Andy Hau-yan Ho, Hao Luo, Gloria Hoi-yan Wong, Bobo Hi-po Lau, Terry Yat-sang Lum & Karen Siu-lan Cheung To cite this article: Jennifer Yee-man Tang, Andy Hau-yan Ho, Hao Luo, Gloria Hoi-yan Wong, Bobo Hi-po Lau, Terry Yat-sang Lum & Karen Siu-lan Cheung (2015): Validating a Cantonese short version of the Zarit Burden Interview (CZBI-Short) for dementia caregivers, Aging & Mental Health, DOI: 10.1080/13607863.2015.1047323 To link to this article: http://dx.doi.org/10.1080/13607863.2015.1047323
Published online: 27 May 2015.
Submit your article to this journal
Article views: 49
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=camh20 Download by: [University of Leeds]
Date: 04 October 2015, At: 23:23
Aging & Mental Health, 2015 http://dx.doi.org/10.1080/13607863.2015.1047323
Validating a Cantonese short version of the Zarit Burden Interview (CZBI-Short) for dementia caregivers Jennifer Yee-man Tang
a
*, Andy Hau-yan Hob,a, Hao Luoa,c, Gloria Hoi-yan Wonga,d, Bobo Hi-po Laue, Terry Yat-sang Luma,f and Karen Siu-lan Cheunga,f
a
Sau Po Centre on Ageing, The University of Hong Kong, Hong Kong, China; bDivision of Psychology, School of Humanities and Social Sciences, Nanyang Technological University, Singapore; cDepartment of Sociology, Tsinghua University, Beijing, China; dDepartment of Psychiatry, The University of Hong Kong, Hong Kong, China; eDepartment of Psychology, The University of Hong Kong, Hong Kong, China; fDepartment of Social Work and Social Administration, The University of Hong Kong, Hong Kong, China
Downloaded by [University of Leeds] at 23:23 04 October 2015
(Received 13 November 2014; accepted 21 April 2015) Objectives: The present study aimed to develop and validate a Cantonese short version of the Zarit Burden Interview (CZBI-Short) for Hong Kong Chinese dementia caregivers. Methods: The 12-item Zarit Burden Interview (ZBI) was translated into spoken Cantonese and back-translated by two bilingual research assistants and face validated by a panel of experts. Five hundred Chinese dementia caregivers showing signs of stress reported their burden using the translated ZBI and rated their depressive symptoms, overall health, and care recipients’ physical functioning and behavioral problems. The factor structure of the translated scale was identified using principal component analysis and confirmatory factor analysis; internal consistency and item-total correlations were assessed; and concurrent validity was tested by correlating the ZBI with depressive symptoms, self-rated health, and care recipients’ physical functioning and behavioral problems. Results: The principal component analysis resulted in 11 items loading on a three-factor model comprised role strain, selfcriticism, and negative emotion, which accounted for 59% of the variance. The confirmatory factor analysis supported the three-factor model (CZBI-Short) that explained 61% of the total variance. Cronbach’s alpha (0.84) and item-total correlations (rho D 0.390.71) indicated CZBI-Short had good reliability. CZBI-Short showed correlations with depressive symptoms (r D 0.50), self-rated health (r D ¡0.26) and care recipients’ physical functioning (r D 0.180.26) and disruptive behaviors (r D 0.36). Conclusions: The 12-item CZBI-Short is a concise, reliable, and valid instrument to assess burden in Chinese dementia caregivers in clinical and social care settings. Keywords: dementia and cognitive disorders; caregiving; stress/burden; mental health assessments
Introduction The number of older Chinese adults with dementia from Mainland China was estimated to be more than 9 million in 2010 and is expected to reach 20 million by 2030 (Chan et al., 2013; Wu et al., 2013). The number of caregivers of Chinese dementia patients is expected to increase correspondingly, particularly family caregivers because caring for a parent or spouse is considered a doctrinal responsibility in many Chinese societies. A Hong Kong population based study found that caregivers were more likely to experience poorer physical and mental health than non-caregivers (Ho, Chan, Woo, Chong, & Sham, 2009). However, only a few studies have specifically studied burden of dementia caregivers in Hong Kong (Cheng, Kwok, & Lam, 2014; Cheng, Lam, & Kwok, 2013; Yan & Kwok, 2011), most likely due to the lack of a validated short instrument for measuring caregiver burden in Chinese dementia caregivers. The 22item Zarit Burden Interview (ZBI) has been translated and validated for the assessment of dementia caregiver burden in Asia and different parts of the world (Zarit, Reever, & Bach-Peterson, 1980), but the large number of items may *Corresponding author. Email: [email protected] Ó 2015 Taylor & Francis
discourage its use in research and clinical practice. Considering that caregivers are mostly supported by professionals in the community, a short version will be more readily accepted by the professionals for care planning. To enhance the ease of use, a number of shorter versions of the ZBI have been developed in the West, but no known studies have validated a Chinese short version of the ZBI. A shorter version could be used as an adequate outcome measure that is sensitive to the effects of caregiver intervention (Cheung et al., 2014). Six short versions of the ZBI were evaluated by Higginson, Gao, Jackson, Murray, and Harding (2010). They found the 12item ZBI developed by Bedard et al. (2001) was the best in terms of its good validity, consistency across samples, and ability to measure changes over time. Although these methods had satisfactory psychometric properties, the factor structure of the caregiver burden was inconclusive. The model by Bedard et al. (2001) was composed of two factors; personal strain and role strain. These two factors were initially proposed by Hebert, Bravo, and Preville (2000) and Whitlatch, Zarit, and von Eye (1991), although the distribution of items differed in each model.
Downloaded by [University of Leeds] at 23:23 04 October 2015
2
J.Y.-m. Tang et al.
This inconsistency implies there is a lack of theoretical conceptualization of personal strain and role strain. Whitlatch et al. (1991) defined personal strain as the level of stress of the caregiving experience and role strain as the level of stress due to role conflict and overloading. Based on these definitions, the two-factor models proposed by Bedard and Hebert were not fully compatible with the concepts of personal strain and role strain. For instance, the item ‘being afraid of what the future holds for your relative’ was considered as role strain by Hebert, even though it has little to do with role conflict. Thus, the factor labels appear to be ill matched with the latent constructs. Knight, Fox, and Chou (2000) proposed a three-factor model constituting patient’s dependency, embarrassment/ anger, and self-criticism because the Whitlatch’s model did not fit their data well. Albeit the good model fit, the first two latent factors indicated high level of convergence. Furthermore, Western and Chinese studies found different factor structures (Lai, 2007; Ko, Yip, Liu, & Huang, 2008), which could potentially be due to ethnic or cultural factors such as differences in caregiver characteristics, expectation of caregiving responsibility, and coping strategy (Alzheimer’s Association, 2013; Janevic & Connell, 2001; Torti, Gwyther, Reed, Friedman, Schulman, 2004). The purpose of this study was to develop and validate a Cantonese version of the 12-item ZBI (CZBIShort) previously developed by Bedard, and systematically explore its factor structure for a Hong Kong Chinese population.
Methods Setting and participants The data used in this validation study were drawn from a sample who participated in a one group pretest–posttest study, which investigated the effects of a six-month caregiver intervention program in Hong Kong, the ‘Reaching out Dementia Caregiver Support Project’ (REACH-HK). The data were obtained at the baseline assessment of the REACH-HK study between October 2011 and January 2014. Five hundred Chinese caregivercare recipient dyads were recruited from 11 non-governmental organizations in the community. The inclusion criteria for the caregivers in the study (Cheung et al., 2014; Lou, Lau, & Cheung, in press) were as follows: (1) aged 21 years or above, (2) having a family member diagnosed with dementia, (3) having no immediate plans of leaving Hong Kong during the intervention and follow-up assessment, (4) provided care or being with the care recipient for no less than two hours per day for at least six months before recruitment, and (5) reported to have at least two symptoms of caregiver stress (e.g., exhaustion, crying, anger, depression). Each symptom was measured using a screening question with binary response options (yes or no). The exclusion criteria were as follows: (1) non-Chinese or non-Chinese speaking, (2) actively receiving cancer treatment, (3) having plans to institutionalize the care recipient within six months, (4) participating in another clinical trial, and (5) cognitively impaired (Short Portable
Mental Status Questionnaire score 4). This study was approved by the Human Research Ethics Committee for Non-Clinical Faculties of the University of Hong Kong (reference number: EA270811). Scale development The 12-item ZBI developed by Bedard et al. (2001) was based on a combination of factor loadings and item-total correlations across three time points for two dementia samples. Each item subjectively measured caregiver burden on a 5-point scale (0 D never to 4 D very frequently). We did not adopt the translated items from Chan, Lam, and Chiu (2005) who previously translated the 22-item scale in written form of Chinese. The written language was different from spoken colloquial Cantonese used by most participants. Interventionists would read out the questions to participants who are of lower education or illiterate; therefore, the development of spoken-Cantonese version of the scale was needed and recommended by interventionists. The scale was translated into spoken Cantonese by two bilingual research assistants with nursing and psychology backgrounds using the back-translation procedure proposed by Brislin and Freimanis (2001). One research assistant translated the items from English to spoken Cantonese and the other back-translated the items from spoken Cantonese to English. The principal investigator inspected the cross-cultural adaptation and the scale translation process in terms of vocabulary, grammar, and syntax. Face validity of the translated scale was assessed by the interventionists, project advisors, and investigators, who collectively had backgrounds in demography, clinical psychology, gerontology, social work, and nursing. The evaluation panel assessed whether the items were (1) relevant to caregiver burden, (2) relevant to the context of dementia caregiving in Hong Kong, and (3) suitable for older caregivers in terms of acceptability and readability. The evaluation panel agreed the items showed adequate face validity. One hundred and twenty-four registered social workers (interventionists) were trained to elicit caregiver burden by face-to-face interviews using the translated 12-item ZBI. The translated 12-item scale was subsequently piloted on 24 caregivers, and no difficulties were reported in administering the scale. Measures for scale validation Depressive symptoms were assessed using the Chinese version of the Center for Epidemiologic Studies Depression Scale (CESD) (Chi & Boey, 1993). Each of the 20 items in CESD was rated on a 4-point scale giving a total score ranging from 0 to 60, with a higher score indicating a higher level of depression. Caregivers self-reported their health using a single item ‘In general, would you say your health is?’ and rated on a 5-point scale (0 D poor to 4 D excellent) (Idler & Benyamini, 1997). Care recipient’s physical functioning was assessed through the caregiver’s proxy-report of the care recipient’s performance in specific self-care tasks using the Katz’s activities of daily
Aging & Mental Health living (ADL; 8 items) scale (Katz, Ford, Moskowitz, Jackson, & Jaffe, 1963) and the Lawton’s instrumental activities of daily living (IADL; 7 items) scale (Lawton & Brody 1969). Each item elicited a binary response and a higher total score indicated a lower level of physical functioning. Care recipient’s behavioral problem was measured using the Revised Memory and Behavioral Problems Checklist (RMBPC) (Roth et al., 2003). The checklist comprised 24 items that generate scores for three subscales, namely memory-related problems, depression, and disruptive behaviors. Each item asked how frequent in the past week the care recipient exhibited a specific problem (0 D not at all to 3 D daily or more).
Downloaded by [University of Leeds] at 23:23 04 October 2015
Statistical analysis Individual items of the ZBI were presented as mean scores. We used confirmatory factor analysis (CFA) to test whether our data fitted a one-factor model (i.e., caregiver burden) and the two-factor model proposed by Bedard. The CFA model was estimated using covariance matrix and the maximum likelihood method. An acceptable model is conventionally indicated by the fit indices, including the chi-square test (p > 0.05), root mean square error of approximation (RMSEA, 0.06), comparative fit index (CFI, 0.95), non-normal fit index (NNFI, 0.95), and standardized root mean square residual (SRMR, 0.08) (Hu & Bentler, 1999). For results indicating a poor fit for the one-factor model and Bedard’s model, we subsequently used principal component analysis (PCA) with oblimin rotation to identify the factor structure of the 12-item ZBI. Components with an eigenvalue greater than 1 were included in the proposed model. The sample was randomly split into two sub-samples for PCA (n D 224) and CFA (n D 225). The CZBI-Short was validated using a number of tests. Cronbach’s alpha estimates of internal consistency and item-total correlations were obtained. Concurrent validity was tested by correlating the ZBI score with CESD, self-rated health, ADL, IADL, and RMBPC. Correlation coefficients for item-total correlations and concurrent validity were estimated by Pearson’s (r) or Spearman’s method (rho), where appropriate. Results The mean (SD) age of the 500 caregivers was 63.6 (12.6) years. The majority of caregivers were female (n D 389, 78%) and were spouses (n D 254, 51%) or children of the care recipients (n D 222, 44%). Most caregivers were married (n D 368, 74%), whereas the rest were single (n D 92, 18%), widowed (n D 12, 2%), divorced or divorcing (n D 20, 4%). Approximately one-tenth of caregivers had no formal education (n D 58, 12%), whereas the others had completed primary (n D 153, 31%), secondary (n D 94, 19%), and tertiary (n D 55, 11%) education. Data on the 12-item ZBI were only available in 447 out of 500 caregivers because one or more values were missing. The excluded caregivers (n D 53) did not have significant differences in the above demographic
3
characteristics compared to those included in the study. The mean (SD) score of the 12-item ZBI was 19.1 (8.8); item-total correlations were good, ranging from 0.39 to 0.71 (Table 1); and Cronbach’s alpha was 0.84. An initial CFA was performed to test whether our data fitted a one-factor model, and Bedard’s two-factor model comprised personal strain and role strain. The goodnessof-fit indices showed both models were inadequate (as shown by p < 0.05) for our Chinese sample (one-factor model: x2 D 579.2, df D 54, p < 0.001; RMSEA D 0.148; CFI D 0.697; NNFI D 0.630; SRMR D 0.089. Two-factor model: x2 D 232.6, d.f. D 53, p < 0.001; RMSEA D 0.087; CFI D 0.897; NNFI D 0.871; SRMR D 0.076). The PCA generated three factors with eigenvalues greater than 1, which explained 59% of the total variance. Factor 1 (items 1, 2, 4, 7, 8, and 9; 29% variance explained) was related to role strain due to caregiving; Factor 2 (items 11 and 12; 16% variance explained) involved the feelings of ‘self-criticism’ in caregiving, and Factor 3 (items 3, 5, and 10; 14% variance explained) involved the negative emotion related to caregiving. The three factors were inter-correlated with role strain and self-criticism showing the strongest inter-correlation, but with self-criticism and negative emotion showing the weakest inter-correlation (Table 2). Item 6 (suffered health) did not have sufficient loading (>0.30) on any of the three factors and was not included in the subsequent CFA. Loadings for the individual items are shown in Table 1. The CFA of the 11 items revealed that some fit indices were acceptable in the three-factor model (x2 D 87.0, df D 41, p < 0.001; RMSEA D 0.071; CFI D 0.943; NNFI D 0.924; SRMR D 0.050), which explained 61% of the total variance. The modification indices showed that the addition of item 8 (suffered social life) showed the largest increase in the chi-square value compared with the other items. We did not drop item 8 from the scale because the item contained good face validity, even the CFA fit indices without item 8 was satisfactory (x2 D 45.8, df D 32, p D 0.055; RMSEA D 0.044; CFI D 0.979; NNFI D 0.970; SRMR D 0.044). Factor loadings of CFA are shown in Table 1. The mean (SD) scores for Factors 1, 2, and 3 were 1.48 (0.89), 1.74 (0.86), and 1.46 (1.15), respectively. The Cronbach’s alpha for Factors 1, 2, and 3 were 0.82, 0.87, and 0.59, respectively. The CZBI-Short total score showed moderate correlation with CESD (r D 0.50; p < 0.001) and modest correlations with self-rated health (r D ¡0.26; p < 0.001), IADL (r D 0.26; p < 0.001), ADL (r D 0.18; p < 0.001), RMBPC memory-related problems (r D 0.35; p < 0.001), RMBPC disruptive behaviors (r D 0.36; p < 0.001), and RMBPC depression (r D 0.18; p D 0.01). The three proposed factors showed distinctive correlation patterns with the above measures (Table 2). Role strain was correlated with CESD, self-reported health, ADL, IADL, and RMBPC subscales; self-criticism was correlated with all measures except for ADL severity; whereas negative emotion was only correlated with CESD. Taken together, the CZBI-Short demonstrated satisfactory internal consistency and concurrent validity.
0.55 0.40
p-value of the item-total correlation coefficient (rho) for each item was
ISSN: 1360-7863 (Print) 1364-6915 (Online) Journal homepage: http://www.tandfonline.com/loi/camh20
Validating a Cantonese short version of the Zarit Burden Interview (CZBI-Short) for dementia caregivers Jennifer Yee-man Tang, Andy Hau-yan Ho, Hao Luo, Gloria Hoi-yan Wong, Bobo Hi-po Lau, Terry Yat-sang Lum & Karen Siu-lan Cheung To cite this article: Jennifer Yee-man Tang, Andy Hau-yan Ho, Hao Luo, Gloria Hoi-yan Wong, Bobo Hi-po Lau, Terry Yat-sang Lum & Karen Siu-lan Cheung (2015): Validating a Cantonese short version of the Zarit Burden Interview (CZBI-Short) for dementia caregivers, Aging & Mental Health, DOI: 10.1080/13607863.2015.1047323 To link to this article: http://dx.doi.org/10.1080/13607863.2015.1047323
Published online: 27 May 2015.
Submit your article to this journal
Article views: 49
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=camh20 Download by: [University of Leeds]
Date: 04 October 2015, At: 23:23
Aging & Mental Health, 2015 http://dx.doi.org/10.1080/13607863.2015.1047323
Validating a Cantonese short version of the Zarit Burden Interview (CZBI-Short) for dementia caregivers Jennifer Yee-man Tang
a
*, Andy Hau-yan Hob,a, Hao Luoa,c, Gloria Hoi-yan Wonga,d, Bobo Hi-po Laue, Terry Yat-sang Luma,f and Karen Siu-lan Cheunga,f
a
Sau Po Centre on Ageing, The University of Hong Kong, Hong Kong, China; bDivision of Psychology, School of Humanities and Social Sciences, Nanyang Technological University, Singapore; cDepartment of Sociology, Tsinghua University, Beijing, China; dDepartment of Psychiatry, The University of Hong Kong, Hong Kong, China; eDepartment of Psychology, The University of Hong Kong, Hong Kong, China; fDepartment of Social Work and Social Administration, The University of Hong Kong, Hong Kong, China
Downloaded by [University of Leeds] at 23:23 04 October 2015
(Received 13 November 2014; accepted 21 April 2015) Objectives: The present study aimed to develop and validate a Cantonese short version of the Zarit Burden Interview (CZBI-Short) for Hong Kong Chinese dementia caregivers. Methods: The 12-item Zarit Burden Interview (ZBI) was translated into spoken Cantonese and back-translated by two bilingual research assistants and face validated by a panel of experts. Five hundred Chinese dementia caregivers showing signs of stress reported their burden using the translated ZBI and rated their depressive symptoms, overall health, and care recipients’ physical functioning and behavioral problems. The factor structure of the translated scale was identified using principal component analysis and confirmatory factor analysis; internal consistency and item-total correlations were assessed; and concurrent validity was tested by correlating the ZBI with depressive symptoms, self-rated health, and care recipients’ physical functioning and behavioral problems. Results: The principal component analysis resulted in 11 items loading on a three-factor model comprised role strain, selfcriticism, and negative emotion, which accounted for 59% of the variance. The confirmatory factor analysis supported the three-factor model (CZBI-Short) that explained 61% of the total variance. Cronbach’s alpha (0.84) and item-total correlations (rho D 0.390.71) indicated CZBI-Short had good reliability. CZBI-Short showed correlations with depressive symptoms (r D 0.50), self-rated health (r D ¡0.26) and care recipients’ physical functioning (r D 0.180.26) and disruptive behaviors (r D 0.36). Conclusions: The 12-item CZBI-Short is a concise, reliable, and valid instrument to assess burden in Chinese dementia caregivers in clinical and social care settings. Keywords: dementia and cognitive disorders; caregiving; stress/burden; mental health assessments
Introduction The number of older Chinese adults with dementia from Mainland China was estimated to be more than 9 million in 2010 and is expected to reach 20 million by 2030 (Chan et al., 2013; Wu et al., 2013). The number of caregivers of Chinese dementia patients is expected to increase correspondingly, particularly family caregivers because caring for a parent or spouse is considered a doctrinal responsibility in many Chinese societies. A Hong Kong population based study found that caregivers were more likely to experience poorer physical and mental health than non-caregivers (Ho, Chan, Woo, Chong, & Sham, 2009). However, only a few studies have specifically studied burden of dementia caregivers in Hong Kong (Cheng, Kwok, & Lam, 2014; Cheng, Lam, & Kwok, 2013; Yan & Kwok, 2011), most likely due to the lack of a validated short instrument for measuring caregiver burden in Chinese dementia caregivers. The 22item Zarit Burden Interview (ZBI) has been translated and validated for the assessment of dementia caregiver burden in Asia and different parts of the world (Zarit, Reever, & Bach-Peterson, 1980), but the large number of items may *Corresponding author. Email: [email protected] Ó 2015 Taylor & Francis
discourage its use in research and clinical practice. Considering that caregivers are mostly supported by professionals in the community, a short version will be more readily accepted by the professionals for care planning. To enhance the ease of use, a number of shorter versions of the ZBI have been developed in the West, but no known studies have validated a Chinese short version of the ZBI. A shorter version could be used as an adequate outcome measure that is sensitive to the effects of caregiver intervention (Cheung et al., 2014). Six short versions of the ZBI were evaluated by Higginson, Gao, Jackson, Murray, and Harding (2010). They found the 12item ZBI developed by Bedard et al. (2001) was the best in terms of its good validity, consistency across samples, and ability to measure changes over time. Although these methods had satisfactory psychometric properties, the factor structure of the caregiver burden was inconclusive. The model by Bedard et al. (2001) was composed of two factors; personal strain and role strain. These two factors were initially proposed by Hebert, Bravo, and Preville (2000) and Whitlatch, Zarit, and von Eye (1991), although the distribution of items differed in each model.
Downloaded by [University of Leeds] at 23:23 04 October 2015
2
J.Y.-m. Tang et al.
This inconsistency implies there is a lack of theoretical conceptualization of personal strain and role strain. Whitlatch et al. (1991) defined personal strain as the level of stress of the caregiving experience and role strain as the level of stress due to role conflict and overloading. Based on these definitions, the two-factor models proposed by Bedard and Hebert were not fully compatible with the concepts of personal strain and role strain. For instance, the item ‘being afraid of what the future holds for your relative’ was considered as role strain by Hebert, even though it has little to do with role conflict. Thus, the factor labels appear to be ill matched with the latent constructs. Knight, Fox, and Chou (2000) proposed a three-factor model constituting patient’s dependency, embarrassment/ anger, and self-criticism because the Whitlatch’s model did not fit their data well. Albeit the good model fit, the first two latent factors indicated high level of convergence. Furthermore, Western and Chinese studies found different factor structures (Lai, 2007; Ko, Yip, Liu, & Huang, 2008), which could potentially be due to ethnic or cultural factors such as differences in caregiver characteristics, expectation of caregiving responsibility, and coping strategy (Alzheimer’s Association, 2013; Janevic & Connell, 2001; Torti, Gwyther, Reed, Friedman, Schulman, 2004). The purpose of this study was to develop and validate a Cantonese version of the 12-item ZBI (CZBIShort) previously developed by Bedard, and systematically explore its factor structure for a Hong Kong Chinese population.
Methods Setting and participants The data used in this validation study were drawn from a sample who participated in a one group pretest–posttest study, which investigated the effects of a six-month caregiver intervention program in Hong Kong, the ‘Reaching out Dementia Caregiver Support Project’ (REACH-HK). The data were obtained at the baseline assessment of the REACH-HK study between October 2011 and January 2014. Five hundred Chinese caregivercare recipient dyads were recruited from 11 non-governmental organizations in the community. The inclusion criteria for the caregivers in the study (Cheung et al., 2014; Lou, Lau, & Cheung, in press) were as follows: (1) aged 21 years or above, (2) having a family member diagnosed with dementia, (3) having no immediate plans of leaving Hong Kong during the intervention and follow-up assessment, (4) provided care or being with the care recipient for no less than two hours per day for at least six months before recruitment, and (5) reported to have at least two symptoms of caregiver stress (e.g., exhaustion, crying, anger, depression). Each symptom was measured using a screening question with binary response options (yes or no). The exclusion criteria were as follows: (1) non-Chinese or non-Chinese speaking, (2) actively receiving cancer treatment, (3) having plans to institutionalize the care recipient within six months, (4) participating in another clinical trial, and (5) cognitively impaired (Short Portable
Mental Status Questionnaire score 4). This study was approved by the Human Research Ethics Committee for Non-Clinical Faculties of the University of Hong Kong (reference number: EA270811). Scale development The 12-item ZBI developed by Bedard et al. (2001) was based on a combination of factor loadings and item-total correlations across three time points for two dementia samples. Each item subjectively measured caregiver burden on a 5-point scale (0 D never to 4 D very frequently). We did not adopt the translated items from Chan, Lam, and Chiu (2005) who previously translated the 22-item scale in written form of Chinese. The written language was different from spoken colloquial Cantonese used by most participants. Interventionists would read out the questions to participants who are of lower education or illiterate; therefore, the development of spoken-Cantonese version of the scale was needed and recommended by interventionists. The scale was translated into spoken Cantonese by two bilingual research assistants with nursing and psychology backgrounds using the back-translation procedure proposed by Brislin and Freimanis (2001). One research assistant translated the items from English to spoken Cantonese and the other back-translated the items from spoken Cantonese to English. The principal investigator inspected the cross-cultural adaptation and the scale translation process in terms of vocabulary, grammar, and syntax. Face validity of the translated scale was assessed by the interventionists, project advisors, and investigators, who collectively had backgrounds in demography, clinical psychology, gerontology, social work, and nursing. The evaluation panel assessed whether the items were (1) relevant to caregiver burden, (2) relevant to the context of dementia caregiving in Hong Kong, and (3) suitable for older caregivers in terms of acceptability and readability. The evaluation panel agreed the items showed adequate face validity. One hundred and twenty-four registered social workers (interventionists) were trained to elicit caregiver burden by face-to-face interviews using the translated 12-item ZBI. The translated 12-item scale was subsequently piloted on 24 caregivers, and no difficulties were reported in administering the scale. Measures for scale validation Depressive symptoms were assessed using the Chinese version of the Center for Epidemiologic Studies Depression Scale (CESD) (Chi & Boey, 1993). Each of the 20 items in CESD was rated on a 4-point scale giving a total score ranging from 0 to 60, with a higher score indicating a higher level of depression. Caregivers self-reported their health using a single item ‘In general, would you say your health is?’ and rated on a 5-point scale (0 D poor to 4 D excellent) (Idler & Benyamini, 1997). Care recipient’s physical functioning was assessed through the caregiver’s proxy-report of the care recipient’s performance in specific self-care tasks using the Katz’s activities of daily
Aging & Mental Health living (ADL; 8 items) scale (Katz, Ford, Moskowitz, Jackson, & Jaffe, 1963) and the Lawton’s instrumental activities of daily living (IADL; 7 items) scale (Lawton & Brody 1969). Each item elicited a binary response and a higher total score indicated a lower level of physical functioning. Care recipient’s behavioral problem was measured using the Revised Memory and Behavioral Problems Checklist (RMBPC) (Roth et al., 2003). The checklist comprised 24 items that generate scores for three subscales, namely memory-related problems, depression, and disruptive behaviors. Each item asked how frequent in the past week the care recipient exhibited a specific problem (0 D not at all to 3 D daily or more).
Downloaded by [University of Leeds] at 23:23 04 October 2015
Statistical analysis Individual items of the ZBI were presented as mean scores. We used confirmatory factor analysis (CFA) to test whether our data fitted a one-factor model (i.e., caregiver burden) and the two-factor model proposed by Bedard. The CFA model was estimated using covariance matrix and the maximum likelihood method. An acceptable model is conventionally indicated by the fit indices, including the chi-square test (p > 0.05), root mean square error of approximation (RMSEA, 0.06), comparative fit index (CFI, 0.95), non-normal fit index (NNFI, 0.95), and standardized root mean square residual (SRMR, 0.08) (Hu & Bentler, 1999). For results indicating a poor fit for the one-factor model and Bedard’s model, we subsequently used principal component analysis (PCA) with oblimin rotation to identify the factor structure of the 12-item ZBI. Components with an eigenvalue greater than 1 were included in the proposed model. The sample was randomly split into two sub-samples for PCA (n D 224) and CFA (n D 225). The CZBI-Short was validated using a number of tests. Cronbach’s alpha estimates of internal consistency and item-total correlations were obtained. Concurrent validity was tested by correlating the ZBI score with CESD, self-rated health, ADL, IADL, and RMBPC. Correlation coefficients for item-total correlations and concurrent validity were estimated by Pearson’s (r) or Spearman’s method (rho), where appropriate. Results The mean (SD) age of the 500 caregivers was 63.6 (12.6) years. The majority of caregivers were female (n D 389, 78%) and were spouses (n D 254, 51%) or children of the care recipients (n D 222, 44%). Most caregivers were married (n D 368, 74%), whereas the rest were single (n D 92, 18%), widowed (n D 12, 2%), divorced or divorcing (n D 20, 4%). Approximately one-tenth of caregivers had no formal education (n D 58, 12%), whereas the others had completed primary (n D 153, 31%), secondary (n D 94, 19%), and tertiary (n D 55, 11%) education. Data on the 12-item ZBI were only available in 447 out of 500 caregivers because one or more values were missing. The excluded caregivers (n D 53) did not have significant differences in the above demographic
3
characteristics compared to those included in the study. The mean (SD) score of the 12-item ZBI was 19.1 (8.8); item-total correlations were good, ranging from 0.39 to 0.71 (Table 1); and Cronbach’s alpha was 0.84. An initial CFA was performed to test whether our data fitted a one-factor model, and Bedard’s two-factor model comprised personal strain and role strain. The goodnessof-fit indices showed both models were inadequate (as shown by p < 0.05) for our Chinese sample (one-factor model: x2 D 579.2, df D 54, p < 0.001; RMSEA D 0.148; CFI D 0.697; NNFI D 0.630; SRMR D 0.089. Two-factor model: x2 D 232.6, d.f. D 53, p < 0.001; RMSEA D 0.087; CFI D 0.897; NNFI D 0.871; SRMR D 0.076). The PCA generated three factors with eigenvalues greater than 1, which explained 59% of the total variance. Factor 1 (items 1, 2, 4, 7, 8, and 9; 29% variance explained) was related to role strain due to caregiving; Factor 2 (items 11 and 12; 16% variance explained) involved the feelings of ‘self-criticism’ in caregiving, and Factor 3 (items 3, 5, and 10; 14% variance explained) involved the negative emotion related to caregiving. The three factors were inter-correlated with role strain and self-criticism showing the strongest inter-correlation, but with self-criticism and negative emotion showing the weakest inter-correlation (Table 2). Item 6 (suffered health) did not have sufficient loading (>0.30) on any of the three factors and was not included in the subsequent CFA. Loadings for the individual items are shown in Table 1. The CFA of the 11 items revealed that some fit indices were acceptable in the three-factor model (x2 D 87.0, df D 41, p < 0.001; RMSEA D 0.071; CFI D 0.943; NNFI D 0.924; SRMR D 0.050), which explained 61% of the total variance. The modification indices showed that the addition of item 8 (suffered social life) showed the largest increase in the chi-square value compared with the other items. We did not drop item 8 from the scale because the item contained good face validity, even the CFA fit indices without item 8 was satisfactory (x2 D 45.8, df D 32, p D 0.055; RMSEA D 0.044; CFI D 0.979; NNFI D 0.970; SRMR D 0.044). Factor loadings of CFA are shown in Table 1. The mean (SD) scores for Factors 1, 2, and 3 were 1.48 (0.89), 1.74 (0.86), and 1.46 (1.15), respectively. The Cronbach’s alpha for Factors 1, 2, and 3 were 0.82, 0.87, and 0.59, respectively. The CZBI-Short total score showed moderate correlation with CESD (r D 0.50; p < 0.001) and modest correlations with self-rated health (r D ¡0.26; p < 0.001), IADL (r D 0.26; p < 0.001), ADL (r D 0.18; p < 0.001), RMBPC memory-related problems (r D 0.35; p < 0.001), RMBPC disruptive behaviors (r D 0.36; p < 0.001), and RMBPC depression (r D 0.18; p D 0.01). The three proposed factors showed distinctive correlation patterns with the above measures (Table 2). Role strain was correlated with CESD, self-reported health, ADL, IADL, and RMBPC subscales; self-criticism was correlated with all measures except for ADL severity; whereas negative emotion was only correlated with CESD. Taken together, the CZBI-Short demonstrated satisfactory internal consistency and concurrent validity.
0.55 0.40
p-value of the item-total correlation coefficient (rho) for each item was
