Official journal of the Pacific Rim College of Psychiatrists

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Asia-Pacific Psychiatry ISSN 1758-5864

ORIGINAL ARTICLE

Validity and reliability of the Chinese version of the Sheehan Disability Scale (SDS-C) Shang-Herng Leu1 MD, Jen-Yu Chou2 MD PhD, Pei-chin Lee3 OTR EdD, Hsiu-Chu Cheng1 RN, Wen-Chuan Shao1 RN MS, Wan-Lin Hsien4 MS, Chieh-Liang Huang5,6 MD & Vincent Chin-Hung Chen7,8,9,10 MD PhD 1 Tsaotun Psychiatric Center, Department of Health, Nantao County, Taiwan 2 Graduate Institute for Humanities in Medicine, Taipei Medical University, Taipei, Taiwan 3 School of Occupational Therapy, Chung Shan Medical University, Taichung, Taiwan 4 Department of Psychiatry, Cardinal Tien Hospital Yonghe Branch, New Taipei City, Taiwan 5 College of Medicine, China Medical University, Taichung, Taiwan 6 Center for Drug Abuse & Addiction, China Medical University Hospital, Taichung, Taiwan 7 Department of Psychiatry, Chung Shan Medical University, Taichung, Taiwan 8 Department of Psychiatry, Chung San Medical University Hospital, Taichung, Taiwan 9 Chang Gung Medical Foundation, Chiayi Chang Gung Memorial Hospital, Chiayi, Taiwan 10 Chang Gung University, Chiayi, Taiwan

Keywords depression, functional impairment, Sheehan Disability Scale, validity Correspondence Vincent Chin-Hung Chen, 259 Wen-Hwa 1st Road, Kwei-Shan Tao-Yuan 333, Taiwan. Tel: 886 5 362 1000 Fax: 886 5 362 3002 Email: [email protected] Dr Chieh-Liang Huang contributes equally to Dr Shang-Herng Leu. Received 23 July 2013 Accepted 23 February 2015 DOI:10.1111/appy.12182

Asia-Pacific Psychiatry 7 (2015) 215–222 © 2015 Wiley Publishing Asia Pty Ltd

Abstract Introductions: This study aims to evaluate the validity and reliability of the Chinese version of the Sheehan Disability Scale (SDS-C) among depression patients in Taiwan. Methods: To validate the SDS-C, two samples were selected: Sample 1 (n = 78) consisted of patients diagnosed with Depressive Disorder, while sample 2 (n = 63) consisted of a nondepressive population. Sample 1 was evaluated with SDS twice with 7–14 days interval to measure test–retest reliability. Both samples were also evaluated with The Centre for Epidemiologic Studies Depression Scale (CESD), Family APGAR (adaptation, partnership, growth, affection, resolve) score, the Global Assessment of Functioning (GAF), and brief questionnaire of the World Health Organization Quality of Life instrument (WHOQOL-BREF) and by a psychiatrist. The two samples were combined to measure validity. Results: In concurrent validity, SDS-C scores were significantly correlated with the total score of GAF. The discriminative validity was carried out by comparing the score of SDS-C between subjects with and without current depressive disorder (t = 12.32, df = 139, P < 0.001). Another discriminative validity by receiver-operating characteristic analysis showed the optimal cut-point was >11 (sensitivity: 82.1, specificity: 93.7). The area under the curve was 0.93 (±0.02). For the factor validity, principal components analysis showed that a single factor solution was the best solution accounting for 88.9% of the variance. Regarding the construct validity, SDS-C scores were significantly correlated with CESD, WHOQOL-BREF, and the Family APGAR score. For test–retest reliability, the intra-class correlation coefficient for the total SDS-C score was 0.89 (95% confidence interval 0.82–0.93) and internal consistency Cronbach’s alpha was 0.94. Discussion: The SDS-C was found to be a valid and reliable instrument for current depressive disorder patients in Taiwan.

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Introduction The burden of depression on the society has been noted globally. (Murray and Lopez, 1996) Several research reports have shown that significant impairment in social, family, and occupational functioning is found among patients with depressive disorders (Wells et al., 1989; Olfson et al., 1997). Worldwide, the psychiatric profession has been trying to address concerns through its research and clinical endeavors. Several tools have been established to evaluate the severity of depressive symptoms, some of which have been translated into the Chinese language (Chan, 1996; Lee et al., 1998; Heh, 2001). There are also some instruments that have been developed originally in Chinese (Lee et al., 2003). However, these measures, focusing on symptoms, tend to overlook the importance of functional disability, which is a crucial and indispensable part in the diagnosis of depression according to Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision DSM-IV-TR; Mintz et al., 1992; American Psychiatric Association, 2000). Without the evaluation of functional impairment, the status of relapse, recurrence, remission, and recovery cannot be gauged with symptom severity alone. (Frank et al., 1991; Kelsey, 2001; Lecrubier, 2002) Unfortunately, most of the existing instruments assess symptom severity instead of disability. Some instruments have been developed to meet the needs of rating and tracking mental health-related impairment, but most of the existing scales are quite long and difficult to administer. (Sheehan and Sheehan, 2008) The Sheehan Disability Scale (SDS) is one of the most extensively used and tested among the very limited disability measurement resources (Sheehan and Sheehan, 2008). Some researchers have validated its psychometric properties among patients with bipolar disorder, panic disorder, post-traumatic disorder, and other anxiety disorders (Leon et al., 1992; Placchi, 1997; Gonzalez et al., 1998; Neal et al., 2004; Arbuckle et al., 2009) as well as those with depressive disorders (Olfson et al., 1997; Erkens et al., 2008; Arbuckle et al., 2009). SDS is a patient-rated tool evaluating functional disability in work, social, and family life (Sheehan and Sheehan, 2008) with only three self-rated items. It has been widely used in antidepressants trials as a treatment outcome measure due to the scale’s simplicity, responsiveness, and predictability (Keller et al., 1993; Rosenberg, 2000; Marshall et al., 2001; Liebowitz et al., 2002; Detke et al., 2004; Freeman et al., 2005). SDS is also extensively used in research regarding treatment

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efficacy for psychosocial interventions and in primary care setting (Schulberg et al., 1996; Katzelnick et al., 2000; McQuaid et al., 2000; Galassi et al., 2001; Mirod et al., 2001; Hirschfeid et al., 2002; Herbert et al., 2005). In Taiwan, depression has also been a major concern in recent decades. The rapid and continuous increase of cost for treatment and impairment poses a great burden on society (Chan et al., 2006). The need for a measurement tool identifying functional disability in both clinical and research settings is significant. The aim of this research was to establish a Chinese version of the Sheehan Disability Scale (SDS-C) and evaluating its reliability among patients with depressive disorders in Taiwan.

Methods Subjects were recruited if they were at least 18 years of age, met the DSM-IV-TR criteria for current major depressive disorder or dysthymia, had no change in treatment in the past 4 weeks, were fluent in Chinese, and were willing and able to provide written informed consent and comply with the study requirements. Subjects with a clinically significant or unstable medical condition, bipolar I disorder, bipolar II disorder, illiteracy and learning difficulties, psychotic disorders, substance abuse, or substance dependence (other than caffeine or nicotine) in the past 3 months were excluded. All diagnostic interviews were carried out by a senior attending psychiatrist according to DSMIV-TR criteria. Study design and data collection procedures The SDS was first forward translated from English to Chinese by one psychiatrist and then back-translated to English by an independent psychiatrist. To establish validity and reliability for Chinese SDS, two samples were selected: Sample 1 consists of patients diagnosed with depressive disorder, while sample 2 nondepressive population (hospital staff, family of patients, or other outpatients). Subjects were recruited from outpatient clinic of the Department of Psychiatry in Tsaotun Psychiatric Center in central Taiwan. Patients and their family that came to the department were asked to participate in the project and also provided written informed consent. All patientreported questionnaires were completed before each participant’s clinical interview. All study assessments were completed between August 2010 and June 2011. Both groups of subjects were interviewed by a senior

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S.-H. Leu et al.

psychiatrist using DSM-IV-TR criteria and Global Assessment Functioning (GAF). The psychiatrist, blinded to the results of all above instruments, performed face-to-face interviews to confirm recent diagnosis of mental disorders. Patients were evaluated with SDS twice with a 7-day interval in order to measure test–retest reliability, while the control group was evaluated with SDS once. The two samples were combined to measure construct validity. Both samples also completed the Chinese version of the Center for Epidemiologic Studies Depression Scale (CES-D), the brief questionnaire of the World Health Organization Quality of Life instrument (WHOQOL-BREF), and the Family APGAR (adaptation, partnership, growth, affection, resolve) score during the first visit. We test the predictive validity of SDS-C through comparing the SDS-C score with the Clinical Global Impression – Improvement scale (CGI-I) rating. After 6 weeks of treatment, the psychiatrist rated the CGI-I scale, and the depressive patients completed the SDS-C again. Ethical Considerations The study was approved by constituted Ethics Committee of the institution of Tsaotun Psychiatric Center in Taiwan. Instruments The SDS measures the impairment in three domains: (i) work/school; (ii) social life/leisure; and (iii) family life/home responsibilities. Patients were asked to respond on a visual analogue scale ranging through 0 (no impairment), 1–3 (mild), 4–6 (moderate), 7–9 (marked), and 10 (extreme) disability. Total scores range from 0 to 30. Two new additional questions are added to the original SDS: (i) “DAYS LOST” (how many days in the last week did your symptoms cause you to miss school or work or leave you unable to carry out your normal daily responsibilities?), and (ii) “DAYS UNDERPRODUCTIVE” (how many days in the last week did you feel so impaired by your symptoms, that even though you went to school or work, your productivity was reduced?). The total score of SDS do not include these two items. The GAF is a clinician-administered rating scale evaluating overall psychosocial and occupational functioning. Subjects are given a score between 1 (hypothetically the sickest person) and 100 (hypothetically the healthiest person) divided into 10 equal intervals. (Rey et al., 1995; Soderberg et al., 2005) The Chinese version of The Centre for Epidemiologic Studies Depression Scale (CESD-C) is a 20-item

Asia-Pacific Psychiatry 7 (2015) 215–222 © 2015 Wiley Publishing Asia Pty Ltd

Validity and reliability of SDS-C

self-administered scale assessing the frequency of depressive symptoms in the preceding week. (Radloff, 1977; Chien and Cheng, 1985) It is a Likert-type scale with responses ranging from 1 (experienced rarely or none of the time) to 4 (experienced most or all of the time). The sensitivity and specificity of the Chinese-version CESD in screening depressive illness in community respondents were reported to be 92% and 91%, respectively, with a classification rate of 91.8% at a cutoff point of 15. (Chien and Cheng, 1985) The Family APGAR score can be used to assess the satisfactory degree regarding support and communication from family. (Good, 1979) Higher score means poorer support. The Chinese version of the scale has been validated in Taiwan. (Smilkstein et al., 1982; Chau et al., 1991) The WHOQOL-BREF is the short form of WHOQOL questionnaire. The Chinese version showed internal consistence at 0.70–0.77, test–retest reliability at 0.76–0.80, and content validity at 0.53–0.78 (Yao et al., 2002). Statistical analysis Concurrent validity was assessed by Spearman’s rankorder correlation coefficients between SDS-C total scores and GAF score. Relationships between SDS-C and current depressive disorders and other diagnosis were analyzed by means of Student’s t-tests. Factor validity was assessed by oblique principal component analysis (varimax rotation). All items were tested whether to load on the first factor (>0.40) to support unidimensionality as the original scale. Construct validity was calculated by Spearman’s rank-order correlation coefficients between SDS-C total scores and the sum of CESD, APGAR score, and WHOQOL-BREF. One-way analysis of variance was used to compare the SDS-C and the CGI-I. CGI-I was used to assess how much the patient’s illness has changed and scored as: 1, very much improved; 2, much improved; 3, minimally improved; 4, no change; 5, minimally worse; 6, much worse; or 7, very much worse. We categorized the patients to three groups according to the CGI-I score (Group 1: CGI-I score 1–2, Group 2: CGI-I score 3–4, Group 3: CGI-I score 5–7). Receiver-operating characteristic (ROC) analysis was used to optimize the cutoff point of SDS-C for depression. Test–retest reliability was assessed by intra-class correlation coefficient (ICC). Internal reliability was calculated using Chronbach’s alpha. These analyses will be carried out using SPSS (Statistical Package for the Social Sciences) version 15.0 (SPSS Inc, Chicago, IL, USA).

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Result A total of 141 Taiwanese subjects (30 men and 111women) were recruited. Most were married (68.1%), with the remainder being single (17.0%), divorced (5.7%), or widowed (17.0%). More than 75% had senior high school or college level of education. Among the subjects, 78 were diagnosed with depressive disorders including major depressive disorder (n = 71, 50.4%) and dysthymia (n = 7, 7.5%). Seventy-two of subjects completed the test–retest rating, and 61 of subjects completed at least 6 weeks of treatment. Other diagnostic categories included adjustment disorder (n = 8, 5.7%) and no current mental disorders (n = 55, 39.0%) (Table 1). Validity The concurrent validity of the SDS-C was investigated by analyses of associations between SDS-C and GAF. The results showed significantly negative correlation between both (r = −0.91, P < 0.001). In terms of construct validity, SDS-C scores were significantly correlated with the total score of CESD (r = 0.778, P < 0.001), WHOQOL-BREF (r = −0.641, P < 0.001), and the Family APGAR score (r = 0.391, P < 0.001). Three individual SDS-C items also showed strong association with above scales. For the two additional items of day lost and day unproductive, the results also showed prominent correlation with SDS-C total score (r = 0.53–0.68, P < 0.001) and other measurements except no correlation of day lost with family support (r = 0.11, P = 0.21) (Table 2).

The discriminative validity of the SDS-C was carried out by comparing the scores of SDS-C between subjects with and without current depressive disorder. The difference of SDS-C score between depression patients (SDS-C = 17.9 ± 7.7) and nondepression group (SDS-C = 4.3 ± 4.7) was 13.6 ± 1.0 (t = 12.32, df = 139, P < 0.001) with high effect size (Cohen’s d = 2.13, r = 0.73). ROC analysis showed the optimal cut-point was >11 (sensitivity: 82.1, specificity: 93.7). The area under the curve (AUC) (±SE) was 0.93 (±0.02). For the factorial validity of the SDS-C, principal components analysis showed that a single-factor solution was the best solution accounting for 88.9% of the variance. The mean score of the three CGI-I groups were 7.5 (SD 5.8) for group 1, 15.9 (SD 6.0) for group 2, and 19.7 (SD 6.2) group 3, respectively. The difference was significant (F = 17.8, P < 0.001) and the improved patents (CGI-I group 1) score much lower SDS-C score (Figure 1). Reliability For test–retest reliability, the intra-class correlation coefficient for the total SDS-C score was 0.89 (95% confidence interval [CI] 0.82–0.93), within the “excellent” range (>0.75). For individual items, ICC scores ranged from: item 1, 0.89 (95% CI 0.82–0.93); item 2, 0.89 (95% CI 0.83–0.93); and item 3, 0.89 (95% CI 0.82–0.93). With regards to internal consistency, Cronbach’s alpha was 0.94 with regards to total score. For the additional items of DAYS LOST, the ICC score was 0.76 (0.64–0.86) and DAYS UNDERPRODUCTIVE 0.78 (0.64–0.86).

Table 1. Socio-demographic characteristics of the subjects (n = 141) Variables Gender Work Education

Marriage

Age SDS-C CESD-C GAF

Male Female Full time Non-full time Junior high school or below Senior high school Collage or above Unmarried Married Divorced/ widow

Total n (%)

Depression n (%)

Nondepression n (%)

30 (21.3) 111 (78.7) 91 (64.5) 50 (35.5) 34 (24.1) 53 (37.6) 54 (38.3) 24 (17.0) 94 (66.7) 23 (16.3) Mean (SD) 45.4 (10.5) 11.8 (9.4) 23.1 (13.0) 63.8 (15.9)

13 65 44 34 22 31 25 15 49 14 Mean 44.54 17.85 31.33 52.17

17 46 47 16 12 22 29 9 45 9 Mean 46.37 4.27 12.97 78.19

(16.7) (83.3) (56.4) (43.6) (28.2) (39.7) (32.1) (19.2) (62.8) (17.9) (SD) (10.59) (7.67) (10.44) (8.9)

(27.0) (73.0) (74.6) (25.4) (19.0) (34.9) (46.0) (14.3) (71.4) (14.3) (SD) (10.45) (4.70) (7.48) (9.64)

P (Chi-square test) 0.14 0.03 0.20

0.56

P (t-test) 0.31

Validity and reliability of the Chinese version of the Sheehan Disability Scale (SDS-C).

This study aims to evaluate the validity and reliability of the Chinese version of the Sheehan Disability Scale (SDS-C) among depression patients in T...
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