C International Psychogeriatric Association 2015 International Psychogeriatrics: page 1 of 7 doi:10.1017/S1041610215000162
Development and validation of the geriatric depression inventory in Chinese culture ...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Zhijuan Xie,1,2, ∗ Xiaozhen Lv,1,2, ∗ Yongdong Hu,3 Wanxin Ma,4 Hengge Xie,5 Kai Lin,2,6 Xin Yu1,2,6 and Huali Wang1,2,6 1
Clinical Research Division, Peking University Institute of Mental Health (Sixth Hospital), Beijing 100191, P. R. China Key Laboratory for Mental Health (Peking University), Ministry of Health, Beijing100191, P. R. China 3 Department of Psychological Medicine, Chaoyang Hospital, Capital Medical University, Beijing, P. R. China 4 Department of Geriatric Psychiatry, Chaoyang District Third Hospital, Beijing 100025, P. R. China 5 Department of Geriatric Neurology, Chinese PLA General Hospital, Beijing 100875, P. R. China 6 Psychogeriatric Unit, Peking University Institute of Mental Health, Beijing 100191, P. R. China 2
ABSTRACT
Background: Depression among older adults is under-recognized either in the community or in general hospitals in Chinese culture. This study aimed to develop a culturally appropriate screening instrument for late-life depression in the non-psychiatric settings and to test its reliability and validity for a diagnosis of depression. Methods: Using a Delphi method, we developed a geriatric depression inventory (GDI), consisting of 12 core symptoms of depressive disorder in old age. We investigated its reliability and validity on 89 patients with late-life depression and 249 non-depression controls. Both self-report (GDI-SR) and physician-interview (GDI-RI) versions were assessed. Results: Cronbach’s α coefficient was 0.843 for GDI-SR and 0.880 for GDI-RI. Both GDI-SR and GDI-RI showed good concurrent validity with the 15-item Geriatric Depression Scale (GDS-15) (GDI-SR: r = 0.750, p < 0.001; GDI-RI: r = 0.733, p < 0.001). The area under the curve of the receiver operating characteristic (ROC) was 0.938 for GDI-SR and 0.961 for GDI-RI, suggesting good to excellent discrimination of depression versus non-depression. Using a cut-off of three items endorsed, sensitivity and specificity were 92.1% and 81.9% for GDI-SR, and 93.3% and 87.1% for GDI-RI. Conclusions: The GDI, either based on self-report or rater interview, is a reliable and valid instrument for the detection of depression among older adults in non-psychiatric medical settings in Chinese culture. Key words: depression, old age, screening, sensitivity, specificity
Introduction Depression is one of the most common psychiatric disorders in old age. Its prevalence rate ranges from 1% to 4% in community (Blazer, 2003) and from 4% to 14% in primary care settings or institutions (Kramer et al., 2009). Among older adults, depression increases risk of co-morbidity and self-neglect, decreases physical, cognitive, and social functioning, and thus increases mortality (Blazer, 2003). Yet, it remains under-diagnosed and under-treated (Mulsant and Ganguli, 1999; Small, 2009), especially by non-psychiatrists (Harman Correspondence should be addressed to: Huali Wang, Clinical Research Division, Peking University Institute of Mental Health, No. 51 Huayuanbei Road, Beijing 100191, P. R. China. Phone: +86-10-82801983; Fax: +86-10-62011769. Email: [email protected]. Received 18 Apr 2014; revision requested 19 Jun 2014; revised version received 7 Oct 2014; accepted 18 Jan 2015. ∗ Contributed equally to this work.
et al., 2001). It may be attributed to different presentations among older adults in comparison to younger adults. For example, older adults are less likely to report sadness (Gallo et al., 1994). Sleep disturbance, fatigue, psychomotor retardation, loss of interest in life, and hopelessness about the future may be more prevalent in late-life depression (Christensen et al., 1999). A recent meta-analysis found that older adults with major depression may experience more somatic symptoms, such as fatigue or pain (Hegeman et al., 2012). Many older people with physical discomforts usually visit non-psychiatric clinics (Lv et al., 2004). The limited awareness and lack of appropriate screening instrument of depression in general hospitals or community clinics (Unutzer, 2002) even delay the recognition of late-life depression. Several instruments are commonly used for screening depression in old age, but they are not
2
Z. Xie et al.
quite appropriate for Chinese culture. The Center for Epidemiologic Studies Depression Scale (CESD) (Radloff, 1977) evaluates the frequency of recent depressed mood. Several items, e.g. I cried most of the time, are not well-understood by the elderly (Carleton et al., 2013). Crying in Chinese culture symbolizes moral vulnerability instead of emotional depression. Though the Geriatric Depression Scale (GDS) (Brink et al., 1982) is developed specifically for elderly, there is yet consensus on cut-off points. For 15-item version, the cut-off point varies from 3 to 7, and for 30-item version, 7, 10, or 11 is recommended (Mitchell et al., 2010). In clinical practice, the GDS is not sensitive enough to identify depression. Somatic symptoms or thoughts about self-harm are not adequately evaluated by GDS (Hammond, 2004). Apart from these limitations, the vast majority of these instruments have been developed for a Western cultural background. The expression of emotional problems is quite different in Chinese (Wong et al., 2012). The factor structure of GDS varies significantly depending on the linguistic and cultural factors. Different cultures conceptualize, experience, and express depressive symptoms in different ways, and that there may be no equivalent concepts for depression in certain non-Western cultures (Kim et al., 2013). Chinese older adults tend to deny the presence of depressive symptoms or express it somatically (Parker et al., 2001). Many depressed Chinese people do not report feeling sad, but rather express boredom, discomfort, feelings of pressure in “heart” (“xin” in Chinese pronunciation, in the same meaning of mind in English), and symptoms of pain, dizziness, and fatigue (Kleinman, 2004). Therefore, we explored the clinical core symptoms of depression among older adults in Chinese culture, developed a new screening instrument for potential application in nonpsychiatric clinics, and then tested its psychometric properties.
Methods The study was approved by the institutional review board of Peking University Institute of Mental Health. Written informed consent was obtained from each participant. Development of the Geriatric Depression Inventory (GDI) In reference to diagnostic criteria of Depressive Disorder in the International Classification of Diseases (ICD-10), and scales which are now widely used in clinical practice and epidemiological surveys like GDS, CES-D, and in conjunction with the
clinical experience of our research team members of geriatric psychiatrist, we selected 15 possible core symptoms of depression among Chinese older adults. Descriptive definition was given to each symptom, to make it more understandable and practical for clinical practice. The original 15 core symptoms were as follows: low mood, self-blame, change of appetite, loss of memory, thoughts of selfharm, helpless or despaired, physical complaints, unable to experience pleasure, insomnia, anxiety, feeling lazy and slow, fatigue, hypochondria, hesitation, and loss of interest. In the next stage, we utilized the Delphi method to modify the symptom checklist and descriptive definition for each item. The expert panel consisted of 27 geriatric psychiatrists and 3 psychologists, with 24 from mainland China (21 geriatric psychiatrists and 3 psychologists), 3 from Hong Kong SAR and 3 from Taiwan. Experts from Hong Kong SAR and Taiwan are geriatric psychiatrists and fluent in written and spoken Mandarin. Details and results of the Delphi consensus were reported elsewhere (Xie et al., 2013). After two rounds of survey, the consensus of the core symptoms and descriptive definition was reached. According to opinions of the experts, three of the original 15 symptom items were abandoned, and the title and descriptive definition of remaining items were modified to fit the linguistic background. The final core symptoms and descriptive definitions in the GDI were as follows: change of appetite and body weight (“ddd dd” in Chinese character, same as below), sleep disturbance (“dd d”), physical complaints (“ dd”), fatigue (“ddd”), feeling lazy and slow (“d”), anxiety and being upset (“ddd”), low mood (“d ”), feeling helpless or despaired (“d d d”), self-blame (“d ”), thoughts of self-harm (“dddd”), unable to experience pleasure (“dddd ”), and loss of interest (“d d”). GDI evaluates mood changes in the last two weeks, with “yes” (score = 1) or “no” (score = 0) response. In addition to the rater-interviewed version (GDI-RI), we also develop the self-reported version (GDI-SR) to facilitate implementation in community settings. There are no differences in the items, definition and structure between selfreported and physician-interviewed versions. Pilot testing Eleven older adults aged above 60 years recruited from a general hospital, completed the draft version of the GDI as part of a pilot test. They provided comments on the readability, item wording, and phrasing immediately following completion of the instrument in paper-pencil form. The GDI was
Validation of GDI in China
subsequently reviewed and modified to formulate the final 12-item version, items based on the qualitative and response feedback from participants, theoretical fit, and comprehensiveness. This study represents its first full psychometric assessment.
Validation study of the GDI Participants The participants were consecutively recruited from clinics of neurology, cardiology, and gastroenterology in general hospitals and internal medicine clinics in community health centers in Beijing from November 2013 to March 2014. All participants met the inclusion criteria as following: aged 60 years or above; with normal cognition as indicated with a total score of the eightitem informant interview (AD-8 scale) < 2 (Galvin et al., 2005; Li et al., 2012); having competency in listening, speaking, reading, and writing to complete the interview and questionnaire, voluntary to participate in the study, and sign the informed consent. Those who were previously diagnosed with dementia, depression, and psychiatric disorders were excluded. Those with life-threatening physical conditions, such as severe heart failure, renal failure and liver function failure, disturbances of consciousness and any type of dementia, deficit in thyroid function, and acute stroke were also excluded. To evaluate reliability, both self-reported and physician-interviewed versions of GDI were administered. The GDS-15 (Liu, 1999; He et al., 2008) was administered to all the participants to evaluate the concurrent validity of the GDI. The GDI and GDS-15 were administered on the same day. The test administrators were blinded to the depression diagnosis of participants when administering the GDI and GDS scale. To evaluate test–retest reliability, nine patients with major depressive disorder were separately recruited and administered with GDI one week after the initial evaluation. The diagnosis for each participant was made based on the consensus of two independent senior geriatric psychiatrists. Those who received the consensus diagnosis of depressive disorder were categorized into depression group. Those who did not receive a consensus diagnosis of depression were excluded in data-analysis. The flow diagram of the entire evaluation process is shown in Figure 1. Both groups were included in the evaluation of the sensitivity and specificity of distinguishing depression with a ROC curve analysis. The clinical consensus diagnosis was used as the gold standard for the ROC analysis.
3
Statistical analysis Internal consistency was measured using Cronbach’s coefficient α. The consistency between GDI-SR and GDI-RI was evaluated using κ value. To test concurrent validity, GDI total scores were compared with GDS-15 scores using Spearman’s ρ correlation coefficients. Sensitivity and specificity of the GDI to differentiate depressive disorder from non-depression control were calculated with the ROC analysis. p < 0.05 was considered to be significant for all analyses.
Results Demographic characteristics A total of 384 participants were recruited into this study. 46 participants were excluded due to eligibility screening failure (n = 11), drop out during the interview (n = 7), withdrawal of consent (n = 1), not reaching a clinical consensus diagnosis (n = 12), and incomplete item of GDI-SR or GDIRI (n = 15). In total, 338 participants were included in the validation study. Table 1 summarizes the demographic characteristics of the depression group (N = 89) and non-depression group (N = 249). There were no significant differences in age and gender. Levels of education, marital status, sum score of the GHQ, AD-8, GDS-15, GDI-SR, and GDI-RI were statistically significant different between two groups (p < 0.05). In relative to nondepression group, the sum score of GDS-15, GDISR, and GDI-RI were higher in depression group. Reliability Cronbach’s coefficient α was 0.843 for GDI-SR and 0.880 for GDI-RI. Inter-item correlations coefficients for GDI-SR were ranged from 0.081 to 0582, p < 0.001; item-total correlations were 0.2190.765, p < 0.001. For GDIRI: the inter-item correlations coefficients were 0.0680.690, item-total correlations coefficients were 0.2040.793, p < 0.001 (supplement 1). The κ value of each symptom item between the GDI-SR and GDI-RI ranged from 0.723 to 0.874 (Table 2), indicating a higher reliability between the evaluations based on self-report and rater interview. Test–retest reliability is acceptable (r = 0.680, p = 0.044). Validity The correlation between GDI-SR and GDS-15 was substantial (r = 0.750, p < 0.001), as was the correlation between GDI-RI and GDS-15 (r = 0.733, p < 0.001).
4
Z. Xie et al.
Figure 1. Flow diagram of participant recruitment and validation procedure.
Table 1. Sociodemographic and clinical characteristics of participants DEPRESSION GROUP (N = 89)
NON-DEPRESION GROUP (N = 249)
P-VALUE
............................................................................................................................................................................................................................................................................................................................
Age (years) Gender (N,%) Male Female Lever of education (N,%) Primary and junior middle school High school or equivalency diploma College or above Marriage status (N,%) Married Unmarrieda GHQ score AD-8 score GDS score GDI-SR score GDI-RI score
67.6 ± 6.4
67.8 ± 6.3
0.680
36 (40.4) 52 (58.4)
110 (44.2) 136 (54.6)
0.556
45 (51.1) 21 (23.9) 22 (25.0)
164 (65.9) 43 (17.3) 42 (16.9%)
0.015
71 (79.8) 18 (20.2) 5.20 ± 3.00 0.44 ± 0.50 7.07 ± 3.33 5.91 ± 2.36 6.26 ± 2.41
225 (91.1) 22 (8.9) 0.67 ± 1.46 0.17 ± 0.38 2.06 ± 2.08 1.30 ± 1.76 0.91 ± 1.62
0.005
Development and validation of the geriatric depression inventory in Chinese culture ...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Zhijuan Xie,1,2, ∗ Xiaozhen Lv,1,2, ∗ Yongdong Hu,3 Wanxin Ma,4 Hengge Xie,5 Kai Lin,2,6 Xin Yu1,2,6 and Huali Wang1,2,6 1
Clinical Research Division, Peking University Institute of Mental Health (Sixth Hospital), Beijing 100191, P. R. China Key Laboratory for Mental Health (Peking University), Ministry of Health, Beijing100191, P. R. China 3 Department of Psychological Medicine, Chaoyang Hospital, Capital Medical University, Beijing, P. R. China 4 Department of Geriatric Psychiatry, Chaoyang District Third Hospital, Beijing 100025, P. R. China 5 Department of Geriatric Neurology, Chinese PLA General Hospital, Beijing 100875, P. R. China 6 Psychogeriatric Unit, Peking University Institute of Mental Health, Beijing 100191, P. R. China 2
ABSTRACT
Background: Depression among older adults is under-recognized either in the community or in general hospitals in Chinese culture. This study aimed to develop a culturally appropriate screening instrument for late-life depression in the non-psychiatric settings and to test its reliability and validity for a diagnosis of depression. Methods: Using a Delphi method, we developed a geriatric depression inventory (GDI), consisting of 12 core symptoms of depressive disorder in old age. We investigated its reliability and validity on 89 patients with late-life depression and 249 non-depression controls. Both self-report (GDI-SR) and physician-interview (GDI-RI) versions were assessed. Results: Cronbach’s α coefficient was 0.843 for GDI-SR and 0.880 for GDI-RI. Both GDI-SR and GDI-RI showed good concurrent validity with the 15-item Geriatric Depression Scale (GDS-15) (GDI-SR: r = 0.750, p < 0.001; GDI-RI: r = 0.733, p < 0.001). The area under the curve of the receiver operating characteristic (ROC) was 0.938 for GDI-SR and 0.961 for GDI-RI, suggesting good to excellent discrimination of depression versus non-depression. Using a cut-off of three items endorsed, sensitivity and specificity were 92.1% and 81.9% for GDI-SR, and 93.3% and 87.1% for GDI-RI. Conclusions: The GDI, either based on self-report or rater interview, is a reliable and valid instrument for the detection of depression among older adults in non-psychiatric medical settings in Chinese culture. Key words: depression, old age, screening, sensitivity, specificity
Introduction Depression is one of the most common psychiatric disorders in old age. Its prevalence rate ranges from 1% to 4% in community (Blazer, 2003) and from 4% to 14% in primary care settings or institutions (Kramer et al., 2009). Among older adults, depression increases risk of co-morbidity and self-neglect, decreases physical, cognitive, and social functioning, and thus increases mortality (Blazer, 2003). Yet, it remains under-diagnosed and under-treated (Mulsant and Ganguli, 1999; Small, 2009), especially by non-psychiatrists (Harman Correspondence should be addressed to: Huali Wang, Clinical Research Division, Peking University Institute of Mental Health, No. 51 Huayuanbei Road, Beijing 100191, P. R. China. Phone: +86-10-82801983; Fax: +86-10-62011769. Email: [email protected]. Received 18 Apr 2014; revision requested 19 Jun 2014; revised version received 7 Oct 2014; accepted 18 Jan 2015. ∗ Contributed equally to this work.
et al., 2001). It may be attributed to different presentations among older adults in comparison to younger adults. For example, older adults are less likely to report sadness (Gallo et al., 1994). Sleep disturbance, fatigue, psychomotor retardation, loss of interest in life, and hopelessness about the future may be more prevalent in late-life depression (Christensen et al., 1999). A recent meta-analysis found that older adults with major depression may experience more somatic symptoms, such as fatigue or pain (Hegeman et al., 2012). Many older people with physical discomforts usually visit non-psychiatric clinics (Lv et al., 2004). The limited awareness and lack of appropriate screening instrument of depression in general hospitals or community clinics (Unutzer, 2002) even delay the recognition of late-life depression. Several instruments are commonly used for screening depression in old age, but they are not
2
Z. Xie et al.
quite appropriate for Chinese culture. The Center for Epidemiologic Studies Depression Scale (CESD) (Radloff, 1977) evaluates the frequency of recent depressed mood. Several items, e.g. I cried most of the time, are not well-understood by the elderly (Carleton et al., 2013). Crying in Chinese culture symbolizes moral vulnerability instead of emotional depression. Though the Geriatric Depression Scale (GDS) (Brink et al., 1982) is developed specifically for elderly, there is yet consensus on cut-off points. For 15-item version, the cut-off point varies from 3 to 7, and for 30-item version, 7, 10, or 11 is recommended (Mitchell et al., 2010). In clinical practice, the GDS is not sensitive enough to identify depression. Somatic symptoms or thoughts about self-harm are not adequately evaluated by GDS (Hammond, 2004). Apart from these limitations, the vast majority of these instruments have been developed for a Western cultural background. The expression of emotional problems is quite different in Chinese (Wong et al., 2012). The factor structure of GDS varies significantly depending on the linguistic and cultural factors. Different cultures conceptualize, experience, and express depressive symptoms in different ways, and that there may be no equivalent concepts for depression in certain non-Western cultures (Kim et al., 2013). Chinese older adults tend to deny the presence of depressive symptoms or express it somatically (Parker et al., 2001). Many depressed Chinese people do not report feeling sad, but rather express boredom, discomfort, feelings of pressure in “heart” (“xin” in Chinese pronunciation, in the same meaning of mind in English), and symptoms of pain, dizziness, and fatigue (Kleinman, 2004). Therefore, we explored the clinical core symptoms of depression among older adults in Chinese culture, developed a new screening instrument for potential application in nonpsychiatric clinics, and then tested its psychometric properties.
Methods The study was approved by the institutional review board of Peking University Institute of Mental Health. Written informed consent was obtained from each participant. Development of the Geriatric Depression Inventory (GDI) In reference to diagnostic criteria of Depressive Disorder in the International Classification of Diseases (ICD-10), and scales which are now widely used in clinical practice and epidemiological surveys like GDS, CES-D, and in conjunction with the
clinical experience of our research team members of geriatric psychiatrist, we selected 15 possible core symptoms of depression among Chinese older adults. Descriptive definition was given to each symptom, to make it more understandable and practical for clinical practice. The original 15 core symptoms were as follows: low mood, self-blame, change of appetite, loss of memory, thoughts of selfharm, helpless or despaired, physical complaints, unable to experience pleasure, insomnia, anxiety, feeling lazy and slow, fatigue, hypochondria, hesitation, and loss of interest. In the next stage, we utilized the Delphi method to modify the symptom checklist and descriptive definition for each item. The expert panel consisted of 27 geriatric psychiatrists and 3 psychologists, with 24 from mainland China (21 geriatric psychiatrists and 3 psychologists), 3 from Hong Kong SAR and 3 from Taiwan. Experts from Hong Kong SAR and Taiwan are geriatric psychiatrists and fluent in written and spoken Mandarin. Details and results of the Delphi consensus were reported elsewhere (Xie et al., 2013). After two rounds of survey, the consensus of the core symptoms and descriptive definition was reached. According to opinions of the experts, three of the original 15 symptom items were abandoned, and the title and descriptive definition of remaining items were modified to fit the linguistic background. The final core symptoms and descriptive definitions in the GDI were as follows: change of appetite and body weight (“ddd dd” in Chinese character, same as below), sleep disturbance (“dd d”), physical complaints (“ dd”), fatigue (“ddd”), feeling lazy and slow (“d”), anxiety and being upset (“ddd”), low mood (“d ”), feeling helpless or despaired (“d d d”), self-blame (“d ”), thoughts of self-harm (“dddd”), unable to experience pleasure (“dddd ”), and loss of interest (“d d”). GDI evaluates mood changes in the last two weeks, with “yes” (score = 1) or “no” (score = 0) response. In addition to the rater-interviewed version (GDI-RI), we also develop the self-reported version (GDI-SR) to facilitate implementation in community settings. There are no differences in the items, definition and structure between selfreported and physician-interviewed versions. Pilot testing Eleven older adults aged above 60 years recruited from a general hospital, completed the draft version of the GDI as part of a pilot test. They provided comments on the readability, item wording, and phrasing immediately following completion of the instrument in paper-pencil form. The GDI was
Validation of GDI in China
subsequently reviewed and modified to formulate the final 12-item version, items based on the qualitative and response feedback from participants, theoretical fit, and comprehensiveness. This study represents its first full psychometric assessment.
Validation study of the GDI Participants The participants were consecutively recruited from clinics of neurology, cardiology, and gastroenterology in general hospitals and internal medicine clinics in community health centers in Beijing from November 2013 to March 2014. All participants met the inclusion criteria as following: aged 60 years or above; with normal cognition as indicated with a total score of the eightitem informant interview (AD-8 scale) < 2 (Galvin et al., 2005; Li et al., 2012); having competency in listening, speaking, reading, and writing to complete the interview and questionnaire, voluntary to participate in the study, and sign the informed consent. Those who were previously diagnosed with dementia, depression, and psychiatric disorders were excluded. Those with life-threatening physical conditions, such as severe heart failure, renal failure and liver function failure, disturbances of consciousness and any type of dementia, deficit in thyroid function, and acute stroke were also excluded. To evaluate reliability, both self-reported and physician-interviewed versions of GDI were administered. The GDS-15 (Liu, 1999; He et al., 2008) was administered to all the participants to evaluate the concurrent validity of the GDI. The GDI and GDS-15 were administered on the same day. The test administrators were blinded to the depression diagnosis of participants when administering the GDI and GDS scale. To evaluate test–retest reliability, nine patients with major depressive disorder were separately recruited and administered with GDI one week after the initial evaluation. The diagnosis for each participant was made based on the consensus of two independent senior geriatric psychiatrists. Those who received the consensus diagnosis of depressive disorder were categorized into depression group. Those who did not receive a consensus diagnosis of depression were excluded in data-analysis. The flow diagram of the entire evaluation process is shown in Figure 1. Both groups were included in the evaluation of the sensitivity and specificity of distinguishing depression with a ROC curve analysis. The clinical consensus diagnosis was used as the gold standard for the ROC analysis.
3
Statistical analysis Internal consistency was measured using Cronbach’s coefficient α. The consistency between GDI-SR and GDI-RI was evaluated using κ value. To test concurrent validity, GDI total scores were compared with GDS-15 scores using Spearman’s ρ correlation coefficients. Sensitivity and specificity of the GDI to differentiate depressive disorder from non-depression control were calculated with the ROC analysis. p < 0.05 was considered to be significant for all analyses.
Results Demographic characteristics A total of 384 participants were recruited into this study. 46 participants were excluded due to eligibility screening failure (n = 11), drop out during the interview (n = 7), withdrawal of consent (n = 1), not reaching a clinical consensus diagnosis (n = 12), and incomplete item of GDI-SR or GDIRI (n = 15). In total, 338 participants were included in the validation study. Table 1 summarizes the demographic characteristics of the depression group (N = 89) and non-depression group (N = 249). There were no significant differences in age and gender. Levels of education, marital status, sum score of the GHQ, AD-8, GDS-15, GDI-SR, and GDI-RI were statistically significant different between two groups (p < 0.05). In relative to nondepression group, the sum score of GDS-15, GDISR, and GDI-RI were higher in depression group. Reliability Cronbach’s coefficient α was 0.843 for GDI-SR and 0.880 for GDI-RI. Inter-item correlations coefficients for GDI-SR were ranged from 0.081 to 0582, p < 0.001; item-total correlations were 0.2190.765, p < 0.001. For GDIRI: the inter-item correlations coefficients were 0.0680.690, item-total correlations coefficients were 0.2040.793, p < 0.001 (supplement 1). The κ value of each symptom item between the GDI-SR and GDI-RI ranged from 0.723 to 0.874 (Table 2), indicating a higher reliability between the evaluations based on self-report and rater interview. Test–retest reliability is acceptable (r = 0.680, p = 0.044). Validity The correlation between GDI-SR and GDS-15 was substantial (r = 0.750, p < 0.001), as was the correlation between GDI-RI and GDS-15 (r = 0.733, p < 0.001).
4
Z. Xie et al.
Figure 1. Flow diagram of participant recruitment and validation procedure.
Table 1. Sociodemographic and clinical characteristics of participants DEPRESSION GROUP (N = 89)
NON-DEPRESION GROUP (N = 249)
P-VALUE
............................................................................................................................................................................................................................................................................................................................
Age (years) Gender (N,%) Male Female Lever of education (N,%) Primary and junior middle school High school or equivalency diploma College or above Marriage status (N,%) Married Unmarrieda GHQ score AD-8 score GDS score GDI-SR score GDI-RI score
67.6 ± 6.4
67.8 ± 6.3
0.680
36 (40.4) 52 (58.4)
110 (44.2) 136 (54.6)
0.556
45 (51.1) 21 (23.9) 22 (25.0)
164 (65.9) 43 (17.3) 42 (16.9%)
0.015
71 (79.8) 18 (20.2) 5.20 ± 3.00 0.44 ± 0.50 7.07 ± 3.33 5.91 ± 2.36 6.26 ± 2.41
225 (91.1) 22 (8.9) 0.67 ± 1.46 0.17 ± 0.38 2.06 ± 2.08 1.30 ± 1.76 0.91 ± 1.62
0.005
