Psychometric testing of the Depressive Cognition Scale in Korean adults

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Applied Nursing Research 25 (2012) 264 – 270 www.elsevier.com/locate/apnr

Psychometric testing of the Depressive Cognition Scale in Korean adults Eun Ja Yeun, PhD, RNa , Young Mi Kwon, PhD, RNb , Jung A Kim, PhD, RNc,⁎ b

Abstract

a Department of Nursing, Konkuk University, Chungju, Chungbuk 380-701, Republic of Korea Department of Nursing, Kyung-In Women's College, Gyeyang-gu, Incheon 407-740, Republic of Korea c Department of Nursing, Hanyang University, Seoungdong-gu, Seoul 133-791, Republic of Korea Received 8 July 2010; revised 21 April 2011; accepted 26 April 2011

This study translated the Depressive Cognition Scale (DCS) from English into Korean and tested the reliability and validity of the scale. Data were from a convenient sample of 795 communitydwelling Korean adults with a self-administered questionnaire. With regard to the reliability estimate, the internal consistency of the Korean version of the DCS (K-DCS) was acceptable, where the Chronbach's alpha is .93 and the average item-to-total correlation r = .760. With regard to the validity estimate, the mean scores of the K-DCS were significantly different according to gender, age, and marital status. A single factor was extracted that accounted for 67.37% of the total variance. The average score of the K-DCS also correlated significantly with the subscales of the Korean version of the Profile of the Mood States Brief Form. These findings suggest that the K-DCS can be used as a reliable and valid measure of depressive cognition among Korean adults. © 2012 Elsevier Inc. All rights reserved.

1. Introduction According to a recent World Health Organization (2008) report, depression (unipolar depression) makes a large contribution to the burden of disease, being at third place worldwide but at first place in middle- and high-income countries. As one of the most common psychiatric disorders, depression is a mental disorder characterized by persistent sadness, loss of interest in normal daily living activities, and decreased energy. People with depression feel hopeless, worthless, and helpless and have difficulty concentrating, remembering, and making decisions. They may also experience loss of appetite or overeat, leading to weight loss or gain, insomnia or excessive sleeping, lack of energy, and inability to concentrate. Changes in mood and thought processes are common; feeling of worthlessness, restlessness, irritability or excessive guilt, and recreant thought of death or suicide can also occur (American Psychological Association, 2010; Sousa, Zauszniewski, Mendes & Zanetti, 2005). According to Beck and colleague's the cognitive theory of depression, the depressive cognitions include negative views of the self, the current experiences/environment, and ⁎ Corresponding author. Tel.: +82 2 2220 0799; fax: +82 2 2297 8613. E-mail addresses: [email protected] (E.J. Yeun), [email protected] (Y.M. Kwon), [email protected] (J.A. Kim). 0897-1897/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.apnr.2011.04.003

the future (Beck, 1974; Beck, Rush, Shaw, & Emery, 1979). The cognitive symptoms of depression, that is, depressive cognition, appear earlier than the affective, motivational, and somatic symptoms constituting clinical depression (Beck, Brown, Steer, Eidelson, & Riskind, 1987; Zauszniewski & Bekhet, 2011). Depressive cognitions can be a precursor of clinical depression. Depressive cognition invariably precedes symptoms of clinical depression (Peden, Rayans, Hall & Grant, 2004), leading to the suggestion that the reduction of depressive cognition is likely to be associated with reduced depression (Coleman, Cole & Wuest, 2009). Thus, measuring depressive cognition can provide important information in terms of screening for clinical depression, whereas identifying depressive cognition in individual cases can be useful to prevent clinical depression (Peden et al., 2004; Sousa, Zanetti, Zauszniewski, Mendes & Daguano, 2008; Zauszniewski, 1997). Accordingly, in response to this need, Zauszniewski (1995) developed the Depressive Cognition Scale (DCS) to assess specific cognitions that may precede the development of clinical depression. The conceptual bases of the DCS are Beck's cognitive theory of depression (Beck, 1967) and Erikson's theory of psychosocial development (Zauszniewski, 1995). The DCS assesses eight depressive cognitions: emptiness, helplessness, hopelessness, loneliness,

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meaninglessness, powerlessness, purposelessness, and worthlessness (Zauszniewski, 1995). The DCS is a paperbased, self-administered, eight-item scale scored on a 6-point Likert-type scale ranging from 0 (strongly disagree) to 5 (strongly agree). Each item in the scale represents a depressive cognition, where sample item statements include “I am hopeful about my future” and “I am in control of my life.” Strong disagreement with an item statement indicates the presence of that specific depressive cognition. The composite score of the scale ranges from 0 to 40. Because the item statements are all phrased in a positive direction, a higher composite score indicates more depressive cognitions (Sousa et al., 2005, 2008; Zauszniewski, 1995, 1997). The DCS was originally developed for use with elder subjects, and an acceptable internal consistency and construct validity, including convergent and discriminate validity, were demonstrated by significant correlation with measures of psychosocial development among functionally independent, community-dwelling older adults (Zauszniewski, 1995). The scale was then subsequently tested with various populations in the United States, including healthy elders (Zauszniewski, 1997), youth, and middleaged women with type 2 diabetes mellitus (Zauszniewski, Chung, Krafcik & Sousa, 2001). The validity and reliability of the scale have also been empirically documented (Zauszniewsk, 1997; Zauszniewski et al., 2001). In 2005, the DCS was translated into Portuguese (Escala Cognitiva de Depressão [ECD]), and its psychometric properties were evaluated using a convenience sample of 40 bilingual Brazilian adults (Sousa et al., 2005) and 82 Brazilian adults with diabetes mellitus, which yielded evidence for the reliability and construct validity of the ECD. Depression is a universal phenomenon. In Korea, the estimated prevalence of depressive symptoms in men and women is 23.1% and 27.4%, respectively, whereas the prevalence of depression in men and women is 6.8% and 10.4%, respectively (Cho, Nam & Suh, 1998). However, little attention has been paid to the early screening of depressive cognition and clinical depression. Therefore, systematic studies are needed to examine the depressive cognition among Koreans. However, despite the clinical implications, no cross-culturally validated Korean language instrument is available to measure depressive cognition. With the increase in international research collaboration, health professionals are becoming more aware of the advantages of using consistent measures to compare outcomes across cultures. Thus, to address this need, this study translated the DCS from English into Korean and tested the reliability and validity of the scale.

2. Methods This study was approved by the Research Ethics Committee of Konkuk University. The subjects were recruited in South Korea from the community and from universities using the following inclusion criteria: (a)

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voluntarily agreed to participate in the study; (b) is older than 18 years; (c) is able to read, write, and hear with or without correction; (d) is able to participate in a 20-minute interview; and (f) has no severe physical or psychological health problems. The final convenience sample consisted of 795 subjects. All subjects agreed to participate after a written description and further verbal information about the research project and signed a consent form. To insure privacy, the names of the subjects were coded. 2.1. Instruments The subjects completed a self-administered questionnaire that included a demographic questionnaire, the Korean Version of the DCS (K-DCS), and a Korean Version of the Profile of the Mood States Brief Form (K-POMS-B). McNair, Loor, and Droppleman (1992) developed the POMS-B to measure an individual's total mood disturbance (TMD). The POMS-B is a shortened version of the original 65-item POMS and consists of 30 adjectives describing feelings and moods that the respondent may have experienced during the past week. The POMS-B consists of 6 identifiable mood states: tension, depression, anger, vigor, fatigue, and confusion. The response format consists of a 5point Likert scale: 0 = not at all, 1 = a little, 2 = moderately, 3 = quite a bit, and 4 = extremely, and is scored in six-factor analytically derived mood dimensions. The score is the sum of the item ratings for each dimension. Reliability coefficients of more than .90 for internal consistency have been reported, with numerous validity studies and normative sample data provided in the manual (McNair et al., 1992). The POMS-B has already been translated into many languages, including Korean. Yeun and Shin-Park (2006) translated the English version of the POMS-B into Korean and evaluated the reliability and validity of the POMS-B for cross-cultural research by comparing the psychometric properties of the POMS-B between American and Korean adult subjects. As such, this study used the K-POMS-B translated and evaluated by Yeun and Shin-Park (2006) to measure the TMD and six mood states to test the construct validity of the K-DCS. The depression, fatigue, anger, tension, and confusion subscales were used to assess the convergent validity with K-DCS. The vigor subscale was used to assess the discriminant validity of the K-DCS. Regarding the convergent validity, it would be expected that the total score of the K-DCS should positively correlated with the depression subscale, as well as the tension, anger, fatigue, and confusion subscales of the K-POMS-B. Fatigue (National Institute of Mental Health, NIMH, 2008), anger, and rage (Busch, 2009); impaired concentration and memory loss; and confusion (Clinical Research Center for Depression, 2006) are all commonly observed among depressed people. With regard to the discriminant validity, it would be theoretically expected that the vigor subscale should be negatively correlated with the K-DCS because the energy level of people with depression is decreased (NIMH, 2008).

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2.2. Translation and assessment of language equivalence The understandability and validity of the K-DCS were examined by Korean clinicians also fluent in the original language of the text (English), along with the inclusion of items common across cultures. The repeated forward– backward translation procedure was adopted as the most commonly quoted adaptation and translation process (Meadows, Bentzen & Touw-Otten, 1996) and was considered the best possible pragmatic strategy for this study. An expert in the Korean language checked the structure and grammar of the items. Another translator was then asked to complete a back translation blindly. Following this back translation, a native English speaker compared the original English and back-translated versions of the instrument, noting any changes to the item descriptions and criteria. The discrepancies were then discussed and agreed upon by both the researcher and the back translator. Thereafter, an expert committee evaluated the translated scale and assessed the item equivalence and content relevance. The expert committee included three nursing professors, a professor of Korean literature, a professor of English literature, a psychiatrist with a PhD and MD, and a psychologist with a PhD, all of whom were bilingual in Korean and English with translation experience, so as to ensure cultural and linguistic equivalence. Finally, the resulting K-DCS was presented to a group of Koreans to evaluate whether the clarity, appropriateness, and content of the items were relevant in a Korean context. 2.3. Data collection At the participating universities (two universities, one women's college), after permission for access to the subjects was granted from course heads, an investigator visited the subjects in a room before or after a lecture and informed them verbally about the research project and the procedures involved. These students were students varying years and majors in school. The questionnaires were distributed to those who agreed to participate in the study and were returned in the envelopes provided immediately after they finished completing the questionnaire in the room. Meanwhile, at the other participating institutions, after permission for access to the subjects was granted from the head of the institution, the investigator visited the subjects in an office room and distributed the questionnaire to them. Approximately 30% (n = 198) of the subjects were asked to answer the questionnaire a second time 2 weeks after the first administration to assess the test–retest reliability of the KDCS. The data collection took place during 2009. 2.4. Data analysis The collected data were managed and analyzed using the Statistical Package for Social Sciences software version 16.0. The statistical significant level was set at p b .05. Descriptive statistics were obtained: the frequency, mean,

standard deviation, and rank of each item in the K-DCS. The internal consistency of the K-DCS was examined by calculating Cronbach's alpha coefficient, whereas the itemto-total correlations of the K-DCS were assessed using the Pearson's correlation coefficient. A minimum value of .8 for Cronbach's alpha is acceptable, and the inter-item correlation should between .30 and .70 (Nunnally & Bernstein, 1994). The item-to-total correlation should be more than .4 (Streiner & Norman, 1995). The intraclass correlation (ICC) was also calculated to determine the test–retest reliability and should be greater than .7 to indicate adequate test–retest reliability (Scientific Advisory Committee of Medical Outcomes Trust, 1995). The validity of the K-DCS was evaluated using three different methods: (a) a t test or oneway analysis of variance test (ANOVA) and Scheffe multiple comparison to examine the differences in the mean score of the K-DCS according to the general characteristics of the subjects, (b) factor analysis using the principal components method to examine the construct validity of the scale, and (c) calculating the Pearson's correlation coefficient between the K-DCS and the POMS to examine the convergent and discriminant validity of the scale.

3. Results 3.1. Subject characteristics As shown in Table 1, 59.6% of the subjects were female and 40.4% were male. The age range of the subjects was 20 to 92 years, with a mean age of 49.39 ± 18.54 years, and the marital status was 58.9% married and 26.3% unmarried. 3.2. Descriptive analysis of K-DCS The scores for each item of the K-DCS ranged from 1.52 to 2.14, and the composite score for all items of the K-DCS was 15.05 ± 7.74 (Table 2). Helplessness (2.14 ± 1.19) had the highest mean score, followed by purposelessness (2.11 ± 1.24), loneliness (2.08 ± 1.12), and emptiness (2.02 ± 1.23). Worthlessness had the lowest mean score of 1.52 ± 1.20. 3.3. Reliability estimate The overall reliability estimate for the K-DCS, that is, Chronbach's alpha, was .93. There was no single item that improved the overall Chronbach's alpha coefficient for the scale. The item-to-total correlation ranged from r =.683 to r =.859, where the average correlation was r =.760. The ICC score for the K-DCS was .93 (Table 2). As shown in Table 3, the inter-item correlations ranged from r =.527 to r =.772. The correlation between meaninglessness and hopelessness, between meaninglessness and worthlessness, and between powerlessness and purposelessness was r =.772 (p b .01), r =.736 (p b .01), and r =.703 (p b .01), respectively. The average inter-item correlation was r =.627.

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Table 1 Sample characteristics and ANOVA of K-DCS scores (N = 795) Variable

Gender

Age (years)

Marital status

n

Male Female Missing 20–29a 30–39b 40–49c 50–59d 60–69e 70–79f ≥80g Missing Unmarrieda Marriedb Bereavedc Divorced/Separatedd Missing

320 473 2 183 34 200 117 115 120 19 7 207 463 95 21 9

%

K-DCS M

SD

t or F

p

40.4 59.6

14.24 15.61

8.00 7.52

−2.448

.015

23.2 4.3 25.4 14.8 14.6 15.2 2.4

10.71 11.38 14.23 14.79 18.73 19.39 24.68

6.16 5.16 6.80 8.06 7.02 7.44 7.49

33.161

.000

a,bbg

26.3 58.9 12.1 2.7

11.22 15.49 20.54 20.38

6.19 7.55 7.09 8.54

42.453

.000

abbbc,d

3.4. Validity estimate As shown in Table 1, the mean scores for the K-DCS were significantly different depending on gender (t = −2.448, p = .015), age (F = 33.161, p b .001), and marital status (F = 41.423, p b .001). The K-DCS scores were higher for the female subjects, bereaved or divorced/separated subjects, and older age group (≥80). A principal components factor analysis was conducted on the K-DCS items. The factor extraction only generated one factor with eigenvalues greater than 1.00 (Table 4). In addition, the scree plot suggested that there was only one dimension underlying the items of the K-DCS, and a single extracted factor explained 67.37% of the variance in the items of the K-DCS. No further rotation was needed because only one factor obtained an eigenvalue greater than 1.00 (Lesthaeghe, 1983). The communality values were greater than .50 for all the items. Plus, every item of the scale had strong factor loadings (≥.748) on the single factor that emerged, exceeding the minimum recommended criterion of .30 (Nunally & Bernstein, 1994). As shown in Table 5, the composite score for the K-DCS showed a weak positive correlation with the K-POMS-B's score for the TMD (r = .388, p b .01). Only the vigor

Scheffe

subscale of the K-POMS-B showed a negative correlation with the composite score of the K-DCS, and the strongest correlation was between two variables (r = −.392, p b .01). 4. Discussion The findings of this study provide evidence of the reliability and validity of the K-DCS. The mean score of each item of the K-DCS was lower than the midpoint of the possibly score range, and the mean score for the K-DCS was 15.05. These findings are much lower than the mean score of the DCS (33.60) in the study by Zauszniewski et al. (2001) for a sample of 83 women with type 2 diabetes. On the other hand, in a study recently published by Sousa, Zauszniewski, and Jaber (2010) for a large sample of 629 adults (mean age was 35.2 years) from a U.S. general population, the mean score of the DCS was 7.59, which is much lower than the mean score for the K-DCS in this study. The higher score for the DCS indicates a great number of depressive cognitions (Zauszniewski, 1995, 1997; Zauszniewski et al., 2001). These differences may be due to the differences in the subject population of the three studies, as only young and middle-aged women with type 2 diabetes were included in

Table 2 Mean score and reliability analysis of K-DCS (N = 795)

Emptiness Helplessness Hopelessness Loneliness Meaninglessness Powerlessness Purposelessness Worthlessness Overall scale a

n = 198.

M

SD

Rank

Item–Total correlation

Cronbach's α if item deleted

Intraclass coefficienta

2.02 2.14 1.75 2.08 1.66 1.79 2.11 1.52 15.05

1.23 1.19 1.18 1.12 1.18 1.11 1.24 1.20 7.74

4 1 6 3 7 5 2 8

.761 .738 .781 .683 .859 .734 .757 .773 .760

.922 .923 .920 .927 .914 .924 .922 .921 .931

.931

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Table 3 Inter-item correlations for K-DCS items (N = 795)

1. 2. 3. 4. 5. 6. 7. 8.

Emptiness Helplessness Hopelessness Loneliness Meaninglessness Powerlessness Purposelessness Worthlessness

1

2

3

4

5

6

7

8

1.000

.694⁎ 1.000

.665⁎ .683⁎ 1.000

.561⁎ .527⁎ .559⁎ 1.000

.682⁎ .671⁎ .772⁎ .666⁎ 1.000

.542⁎ .561⁎ .588⁎ .527⁎ .683⁎ 1.000

.607⁎ .552⁎ .564⁎ .622⁎ .677⁎ .703⁎ 1.000

.636⁎ .581⁎ .662⁎ .527⁎ .736⁎ .649⁎ .660⁎ 1.000

⁎ p b .01.

the study by Zauszniewski et al. (2001), whereas adults without severe physical or psychological health problems were included in this study, and individuals from general population were in the study by Sousa et al. (2010). Depression occurs about two times more frequently in women than in men (Steiner & Yonkers, 1998), and patients with diabetes have nearly twice the risk of comorbid depression compared with the general population (Rush, Whitebird, Rush, Solberg & O'Connor, 2008). In addition, the rate of depression can increase in patients with a chronic illness, such as diabetes. Indeed, depression has been found to be twice as likely to occur in patients with diabetes (Anderson, Freedland, Clouse & Lustman, 2001). The findings of this study showed high internal consistency reliability for K-DCS. A Chronbach's alpha of .93 for the total scale exceeded the recommended coefficient of internal consistency of Chronbach's alpha set at .70 (Nunnally & Bernstein, 1994). The DCS and ECD has demonstrated internal consistency reliability of Chronbach's alpha ranging from .78 to .92 in American and Brazilian samples that involve older adults, diabetic patients (Sousa et al., 2008; Zauszniewski et al., 2001), and adults (Sousa et al., 2005; Sousa et al., 2010). Especially, Chronbach's alpha coefficients were greater than .90 in two studies, including this study. The research participants of these two studies were the younger adults from the general population. It is suggested that values greater than .9 would not be desirable because it may indicate redundancies in the instrument (Streiner & Norman, 2000). However, the appropriate degree of reliability depends upon the use of the instrument (Shaqrah, 2010); an instrument designed to be Table 4 Factor loadings of K-DCS items from factor analysis (N = 795) Items

Factor loading

Communality

Emptiness Helplessness Hopelessness Loneliness Meaninglessness Powerlessness Purposelessness Worthlessness

.820 .803 .839 .748 .898 .800 .819 .831

.673 .645 .705 .559 .807 .641 .671 .690

used as a part of a clinical practice to screen participants for a condition (i.e., depressive cognition) may require extremely precise measures with very high reliabilities (Nunnally & Bernstein, 1994). According to these background and findings of previous study, it would be expected that the K-DCS could be used to screen for depressive cognition and to identify adults at risk for clinical depression. Although the item-to-total correlations in this study were between .683 and .859, and the average item-to-total correlation was .760 for the K-DCS, in previous studies, the average item-to-total correlation was reported as .88 for the EDC (Sousa et al., 2008) and .75 for the DCS. The itemto-total correlation obtained in this study was over the minimum value recommended by Streiner and Norman (1995) and demonstrated a high level of homogeneity. The inter-item correlations in this study were between .527 and .772, and the average inter-item correlation was .627. Most inter-item correlations were in an acceptable range of .30 and .70 (Nunnally & Bernstein, 1994) except for several items of the K-DCS; the inter-item correlation between meaninglessness and hopelessness, between meaninglessness and worthlessness, and between powerlessness and purposelessness was .772, .736, and .703, respectively. In previous studies, the average inter-item correlation was reported as .31 (Zauszniewski, 1995), .30 (Zauszniewski, 1997), .42 (Zauszniewski et al., 2001), and .61 (Sousa et al., 2010) for the DCS, and .32 (Sousa et al., 2005) and .50 (Sousa et al., 2008) for the EDC. These diverse inter-item correlations among studies reported here are probably related to the health status and age of the research participants. This study and only one study (Sousa et al., 2010) were conducted among adults from general population, and the mean age of the research participants was 49 and 35 years, respectively. The average inter-item correlations of these two studies were higher than those reported in the other studies of older adults (Zauszniewski, 1995, 1997), diabetic patients (Sousa et al., 2008; Zauszniewski et al., 2001), and bilingual Brazilian adults (Sousa et al., 2005). These findings support the hypothesis that characteristics such as age, gender, and ethnicity may affect the relationship among the depressive cognitions (Zauszniewski et al., 2001). For the validity estimate, the mean score of the K-DCS was higher for the female subjects than that for the male

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Table 5 Correlation of K-DCS with K-POMS-B (N = 795)

K-DCS Emptiness Helplessness Hopelessness Loneliness Meaninglessness Powerlessness Purposelessness Worthlessness

K-POMS-B TMD

Tension

Depression

Anger

Vigor

Fatigue

Confusion

.388⁎ .364⁎ .292⁎ .312⁎ .328⁎ .333⁎ .285⁎ .309⁎ .333⁎

.250⁎ .224⁎ .169⁎ .208⁎ .201⁎ .222⁎ .185⁎ .215⁎ .215⁎

.346⁎ .323⁎ .253⁎ .300⁎ .272⁎ .294⁎ .250⁎ .277⁎ .303⁎

.274⁎ .250⁎ .175⁎ .210⁎ .233⁎ .239⁎ .222⁎ .239⁎ .229⁎

−.392⁎ −.394⁎ −.369⁎ −.316⁎ −.271⁎ −.318⁎ −.285⁎ −.264⁎ −.357⁎

.257⁎ .221⁎ .190⁎ .178⁎ .256⁎ .213⁎ .197⁎ .233⁎ .204⁎

.227⁎ .203⁎ .152⁎ .183⁎ .238⁎ .178⁎ .155⁎ .196⁎ .196⁎

⁎ p b .01. K-POMS-B, Korean version of Profile of Mood States-Brief; TMD, total mood disturbance.

subjects, indicating that a higher number of Korean female adults experience depressive cognition. This finding is consistent with the results of Cho et al. (1998), where a nationwide sample of 3,711 Korean adults showed that women were significantly more likely to have high levels of depressive symptoms than men. Depression and depressive symptoms are already known to be more prevalent in women than in men, possibly due to genetics, biological reasons, and sociocultural vulnerability (Keita, 2007; Kim et al., 2007). In this study, age was found to have an impact on depressive cognition, which is consistent with the results of Weissman and Klerman (1977, 1985) and Blazer (1989), who suggested that the prevalence of depression and depressive symptoms increases with age. Elderly persons face numerous losses associated with aging, which can precipitate depression (Reed, 1986, Zauszniewski, 1995). As expected, the absence of a spouse due to bereavement, divorce, or separation was a significant factor for depressive cognition. Married people have comparatively low depression rates, as they tend to be emotionally less damaged by stressful experiences than unmarried people (Essex & Johnson, 1982). Plus, spousal support can be a significant factor for coping with distress and increasing the quality of life. The construct validity of the K-DCS was also confirmed by a principle component analysis. A single factor emerged with eigenvalues greater than 1.00, accounting for 67.37% of the total variance, and all eight items of the K-DCS loaded on this factor with loadings exceeding the .30 criterion recommended by Nunnally and Bernstein (1994). The items measuring meaninglessness, hopelessness, and worthlessness were the most representative of the depressive cognitions, as they had the highest factor loadings in the Korean adult sample. However, this finding is partially inconsistent with the results of Zauszniewski et al. (2001), who identified the most representative items as hopelessness, loneliness, and meaninglessness. As this difference may or may not be due to regional and cultural differences related to the samples in the two studies, further testing of the K-DCS with a more diverse sample in a more diverse setting is needed. The convergent and discriminant validity of the KDCS were supported by correlations in the expected directions between the scores for the K-DCS, the subscales of the K-POMS-B, and the score of the TMD.

Therefore, the results of this research project demonstrated that the K-DCS is appropriate for use with Korean adults. The results also revealed that the translated scale can be a useful tool for health care providers and researchers to access the depression mood of the Korean population and may be useful in identifying the effects of nursing intervention and other treatments on study subjects or clients. A growing number of scientific publications are highlighting the need for clinicians and researchers to have access to reliable and valid research instruments in their own language to measure concepts of interest or concern (Sousa et al., 2005). Although depression is one of the most common mental disorders and depressive cognition is known to precede the development of depression, there is currently no screening instrument to measure these symptoms in Korean adults. Therefore, this is the first study to examine depressive cognition among Korean adults and was conducted to translate and validate the DCS among community-dwelling Korean adults. There were several limitations to this study. The first limitation concerns the subjects of this study. Because the subjects were the general public who did not have severe physical or psychological health problem and lived in urban areas, there may be chance that depression and cognitive symptom of depressive were not common among these subjects. A larger and more diverse sample needs to be recruited for in future psychometric testing studies, particularly such participants with chronic illness at higher risk of developing clinical depression in Korean setting. Another limitation was that we only tested the convergent and divergent validity of K-DCS, and the result is modest in this study. Further work conducting a confirmatory factor analysis and comparison with other scales for symptoms of depression/depressive cognition should be done in order to further validate this K-DCS. In summary, the results from this study suggested that the K-DCS can be used as a reliable and valid measure of depressive cognition in Korean adults. The implications to nursing profession and research were as follows. Using a single assessment scale in different countries can reduce variations in international assessments of depressive cognitions. In addition, this study provides strong evidence that the DCS can be used for international comparisons and can

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contribute to the development of international standards for nursing needs and outcome assessments in adults. It is acknowledged that further work is required to validate its use in screening depression/depressive cognition among Koreans to ensure broader acceptability. Acknowledgment The authors gratefully acknowledge Professor Zauszniewski, J. A., PhD, RN, FAAN (Case Western Reserve University, FPB School of Nursing) for her permission to use the DCS. The authors also would like to thank Professor Sung Shim, MD, PhD (Case Western Reserve University School of Medicine, Psychiatry), and Psychologist Young Rae Kim, PhD (University of Akron), for their valuable comments to this article. This study was supported by Konkuk University in 2008.

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