Psychometric properties of the Malay version of the Depression Anxiety Stress Scale-21 (M-DASS21) among nurses in public hospitals in the Klang Valley

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1 109 Psychometric properties of the Malay version of the Depression Anxiety Stress Scale-21 (M-DASS21) among nurses in public hospitals in the Klang Valley Nur Azma BA 1, 2*, Rusli BN 1, Quek KF 1, RM Noah 2 1 Jeffrey Cheah School of Medicine and Health Sciences, Monash University, Malaysia 2 Universiti Kuala Lumpur- Institute of Medical Science Technology (UniKL-Mestech), Malaysia * Corresponding Author: Nur Azma Amin Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Sunway, Selangor, Malaysia Tel: naami5@students.monash.edu Abstract Objectives: This study aims to examine the psychometric properties and validity of the Malay version of Depression Anxiety Stress Scales (M-DASS) among nurses at public hospitals in Klang Valley area of Kuala Lumpur. Methodology: The study is a cross-sectional study design. The questionnaire consists of two sections; participant s socio-demographic information and response to emotional distress experienced by the participants for the past one week. The data were initially analyzed for normality distribution followed by descriptive statistics and further assessed using Explanatory (EFA) and Confirmatory Factor Analysis (CFA). Results: Initial analysis has shown one item of M-DASS21 was cross loaded between factors, hence been omitted, therefore, the DASS was left with 20 items. The items were one dimensional and loaded clearly in the designated factor. The M-DASS20 indicated a good internal consistency of Cronbach s alpha values 0.70 for all subscale. Later, CFA was performed on four different models; it was proven that Model 3b of three factor model M-DASS20 is a preferred fitting model than other proposed models. Conclusion: The results of this study demonstrated that M-DASS is reliable and valid to be applied to the nurse s populations. Key words: Depression, anxiety, stress, reliability, validity Introduction The Depression Anxiety Stress Scales (DASS) consisting of 42 items is developed to maximize discrimination between self-reported depression, anxiety and stress across the full range of these disorders core symptoms 1. Subsequently, a shorter version (DASS-21) consisting of 21 items was

2 110 developed and extensively used in health-related research globally. The DASS was not a diagnostic tool, but a severity measurement scale in which the three subscales were used to assess dimensional components of the depression, anxiety and stress disorders in the community settings. 1 Both versions of DASS were able to differentiate between the depression and anxiety states 2, though ; the DASS-21 was subsequently shown to be more stable and distinctive. 3 The DASS-21 was extensively studied for its validity and reliability in both clinical and nonclinical settings across populations and countries such as those in Australia 4, England 5, and Canada 2 and was translated into several local languages including Bahasa Malaysia 6 8, Spanish 9 and Chinese 10 with acceptable reliabilities (internal consistencies) of between 0.74 to 0.93 for all subscales. Despite its popularity, to date very limited studies using DASS-21 were carried out among the working population particularly among nurses. Therefore, the main objective of the present study was to determine the psychometric properties of the Malay version of the DASS-21 (M-DASS-21) among nurses working in public hospitals, in the Klang Valley area of Kula Lumpur. Methods Study design and participants This is a cross-sectional study design. Female nurses were recruited from four public hospitals in the Klang Valley. Selection of the particular hospitals was based on convenience sampling and support from the respective hospital management. The inclusion criterion was female nurses who were currently working in shift at least one year at the clinical site in the participating hospitals. The study received ethics approval from the Monash University Human Research Ethics Committee (MUHREC) and the Ministry of Health, Malaysia Research Ethics Committee (MREC). Materials and procedures Upon receiving approval from the relevant authorities, and in collaboration with the Matron s office at the respective hospitals, a briefing session was conducted to potential nursing participants. During this session, the subject information documents and informed consent forms were distributed to the participating nurses. The participants were to submit the informed consent forms by the end of the briefing session. The self-administered questionnaires (SAQs) containing the Malay version of DASS-21 (M-DASS-21) were later distributed to those who consented to participate in the study, through the Nurse Manager. The SAQs consist of two sections: sociodemographic profile (age, marital status, education level, work experience, hours worked per week and day and average monthly income) and self-report measures of M-DASS-21 that was adopted from previous local studies 6. The participants remained anonymous, and the completed SAQs were deposited within a week into a locked box located at the Matron s office. The DASS-21 consists of 21-items of self-report according to three subscales (with seven items in each subscale) that measures depression, anxiety, and stress, respectively over the past week. Each item comprises of a statement, and four ordinal responses scored from 0 (Did not apply to me at all) to 3 (Applied to me very much, or most of the time). Scores from each set of seven items were summed up to yield a single subscale score and interpreted as either normal, mild, moderate,

3 111 severe, to extremely severe according to a predetermined criteria. Scores of each subcategory were multiplied by two to compare with the full DASS-42. Higher scores indicate greater severity of the depression, anxiety, or stress disorder 1. Statistical Analysis Data entry and analysis were undertaken using the IBM SPSS Statistics Version Data were checked for completeness and examined for normality distribution using the stem-and-leaf plot and the Kolmogorov-Smirnov Test. For numerical variables, means, and standard deviations were computed for normally distributed variables; medians and interquartile ranges were computed for non-normally distributed variables; for categorical variables, frequencies, and percentages were computed. Previous validations of the Malay version of DASS-21 have indicated a 3-factor solution with each subscale contributed by 7 items 6,7,11 ; however, 3 items (item 15, 20, and 21) loaded poorly into the relevant factors. This was not surprising as the DASS was developed in a Western setting and will have difficulties when translated into the local languages without proper validation. In fact, a recent cross-cultural factor analyses revealed a 3-factor solutions based on 18 items (DASS-18). 12 Therefore, we performed an exploratory factor analysis (EFA) to investigate the factor structure and internal reliability of the 21 items to corroborate the findings. To decide on the number of factors, a scree plot, and eigenvalues (>1) were generated using the principal component analysis (PCA). Factor extraction using PCA was undertaken to obtain the loadings (preferably 0.3 or greater) for each of the factors. 13 Upon obtaining the factor loadings for each factor, the loadings were rotated to maximize high loadings and minimize low loadings so that the simplest possible structure is achieved. Hence, to obtain the simplest structure, the varimax (orthogonal) rotation was employed assuming that the factors were uncorrelated with one another; if the factors were correlated, then an oblique rotation (such as the oblimin, promax or direct quartimin) would be preferred. Following EFA (construct validation), the internal consistency (reliability) of the constructs were examined using the reliability analysis. Cronbach s alpha coefficients were calculated to measure the internal consistency (reliability) for each subscale with a cut-off of 0.70 indicating high internal consistency. 14 AMOS software was used to test the fitness of the factorial models using the maximum likelihood estimation procedure. Assessment of model fitness was based on the value of the chi-square, corresponding p value and goodness-of-fit indices that include the Goodness of Fit Index (GFI) 15, Root Mean Square Error of Approximation (RMSEA) 16, and Comparative Fit Index (CFI). 17 Nonsignificant p values (p>0.05) of the chi square would suggest acceptable and significant model fit. 15 In other words, if the p-value associated with the chi square value is larger than 0.05, the Null hypothesis is accepted, and the model is regarded as being compatible with the population covariance matrix Σ. 18 However, chi square test is sensitive to sample size, meaning the chi square statistics always yielded significant values (p<0.05) when large sample is used, therefore, reject the proposed model. 19 On the other hand, when small sample size is used, the model failed to explain the difference between good and bad model fitting, due to lack of power. In such to the restrictiveness, relative/ normed chi-square (X 2 /df) was introduced to reduce the effect of sample size to the model. 20 Although there is no consensus regarding acceptable ratio for this statistic, recommendations range from to GFI is used to show the relative amount of the variances/covariance in the sample predicted by the population estimation where values 0.95 indicated a good fit 15, however, values greater than 0.90

4 112 is interpreted demonstrating acceptable model fit. 22 Although usually the values ranges between zero and one, higher value indicated better fitting, however, in some occasions; a negative GFI may occur. 18 RMSE demonstrated the model s wellness by choosing the model with lesser number of parameters. RMSEA values of less than would suggest acceptable fit model for continuous data. 3,15,23 The CFI is the revised from of Normed Fit Index (NFI), which is reliable to perform though, in a small sample size. 21 Similarly to NFI, it is ranged 0 to 1, a cut off criterion 0.95 demonstrated good model fitness and accountable for its least sample size effect. 24 Results Socio-demographic characteristics Table 1 summarizes the participants socio-demographic characteristics. The response rate was 91% (455 sets of questionnaires out of 500 distributed; 2 sets have missing data and were excluded from the analysis). The mean (SD) age of the participants was (5.56) years. The majority was Malays (93.6%) and married (76.5%). More than half of the participants have joined the nursing profession for more than 5 years with average service of 7.34 (5.16) years and working at an average of 7.56 (0.91) hours/day or (5.78) hours/week. The Kolmogorov- Smirnov Test for the continuous data showed a highly significant deviated distributions, p=0.00 and were positively skewed. Exploratory Factor Analysis (EFA) Initial extraction using principal component analysis (PCA) with eigenvalues (>1) and scree plot revealed a 3-factor (F1, F2, and F3) solution according to the original study. 4 Using PCA, factor extraction with loadings was generated for all 21 items. Using orthogonal (varimax) rotation, and loading matrices, it was found that only one item (item 3: subscale-depression positive feelings ) significantly cross loaded in more than one factor; therefore is omitted as it failed to show the discrepancy between factors. The first factor (F1) corresponded to the M-DASS21-stress subscale, with all item's loading 0.58 to For the second factor (F2), M-DASS21-Anxiety subscale, items loading 0.52 to The M-DASS21 Depression subscale left with six items in factor 3 (F3) with all items loading The final validated Malay version of M-DASS21 (M- DASS20) is shown in Table 2. Reliability Table 3 shows the item-total correlations and Cronbach s alpha coefficients for M DASS20- Depression, (0.76), M-DASS20-Stress (0.81), M-DASS20-Anxiety (0.77) and M-DASS20-Total (0.90). The modest value of α for DASS20-Depression was expected due to the reduced number of items in the subscale (six items). The item total correlations for each of the subscale items had at least modest correlations with other items ( ), thereby supporting the high Cronbach s alpha coefficients and suggesting good internal consistencies.

5 113 Summary statistics and normative data of M-DASS20 Only 2.9%, 15.7% and 4.2% of respondents reported mild depression, anxiety, and stress, respectively (Table 4). No respondent experienced moderate to very severe stress, but 15.4%, and 1.5% of respondents reported moderate anxiety and depression, respectively. The depression subscale showed the lowest mean score of 3.12 (2.65), while the stress subscale showed the highest mean score of 7.08 (3.30). In general, 26.9% of respondents reported at least one of the emotional distresses (depression, anxiety, and stress). Correlations between scales have shown moderate positive associations with the correlation coefficients ranging from 0.67 to The correlation coefficients between the anxiety subscale and the stress subscale showed a higher correlation coefficient of 0.73; as compared to the depression subscale and anxiety subscale and the depression subscale and the stress subscale showed an almost similar correlation coefficient of 0.68 and 0.67, respectively. Kolmogorov Smirnov tests confirm the obtained score was statistically significant deviated from a normal distribution. Confirmatory Factor Analysis (CFA) A Confirmatory Factor Analysis (CFA) was undertaken to evaluate the model fitness of M- DASS21 and M-DASS20 uses four fit indices: chi-square (χ 2 ), GFI, PGFI, CFI and RMSEA. CFA was carried out to assess the fitness of four models: Model 1 (M-DASS21:3 factors), Model 2 (M-DASS21:1factor), Model 3 (M-DASS20: 3 factors) and Model 4 (M-DASS20:1 factor). Table 5 presented the fit statistics for the models to determine whether a theoretical model fits the data adequately. In the case of inadequate fit, the model may be modified and retesting 25. Henry & Crawford (2005) 5 proposed modification involves correlated errors within items in the same subscale and observed whether the model could possibly yield the better fit that the original model. For the study, the models were tested with and without correlated errors items, The first model tested was M-DASS21 three factor model (1a) 1 of anxiety, depression and stress dimension, which generated a statistically χ 2 [χ 2 (186) =617.83, P <0.05], GFI=0.88, CFI=0.87, and RMSEA: 0.07], indicated a poor fitting. The items were later correlated within items in same subscales and further examined (1b), has showed improvement and fulfilled the criterion for good fit, χ 2 [χ 2 (182) =514.06, P <0.05], GFI=0.90, CFI=0.90, and RMSEA: 0.06]. Next, we tried to confirm the one-factor model of M-DASS-21 (Model 2). Model 2a yielded a higher statistically χ 2 [χ 2 (189) =688.93, P <0.05], GFI=0.87, CFI=0.85, and RMSEA: 0.08] and was not confirmed whereas model 2b showed χ 2 [χ 2 (182) =458.46, P <0.05], GFI=0.87, CFI=0.85, and RMSEA: 0.08]. Followed by Model 3a (M-DASS20 three factor model), discovered a significant χ 2 [χ 2 (167) =564.97, P <0.05], GFI=0.88, CFI=0.87, and RMSEA: 0.07]; while 3b showed a significant χ 2 [χ 2 (163) =469.38, P <0.05], GFI=0.91, CFI=0.90, and RMSEA: 0.06]; and lastly Model 4 of M-DASS20 one factor model, Model 4a generated a statistically χ 2 [χ 2 (170) =644.57, P <0.05], GFI=0.87, CFI=0.85, and RMSEA: 0.08] whereas Model 4b discovered statistically χ 2 [χ 2 (166) =507.80, P <0.05], GFI=0.91, CFI=0.90, and RMSEA: 0.06]. Thus, permitting correlated error has leads to a statistically significant improvement in each of the relevant comparisons (Models 1b, 2b, 3b, and 4b versus 1a, 2a, 3a, and 4a, respectively). The chisquared difference tests confirmed that Models 3b had a significantly superior to other counterparts.

6 114 Discussion The aim of this study was to assess the psychometric properties and validity of the Malay translated version of DASS21 (M-DASS21) among nurses in public hospitals. This study confirmed that M-DASS21, as in the original version of DASS21, has three constructs: depression, anxiety, and stress. EFA was performed to explore the factor loadings, based on the cut-off criterion of at least 0.30 to be a strong factor loading coefficient. For a 3-factor solution, one item (from the depression subscale) revealed significant cross loadings after factor extraction and orthogonal (varimax) rotation and was subsequently omitted. Therefore, 20 items and 3 factors (M-DASS20) left to undergo further analysis. Despite the items was reduced, the findings agreed to the previous local studies which have shown that the remaining items were one-dimensional, clearly loaded in designated factor and obtained good loadings ( ). 6 8 Several alternative models were tested using CFA techniques, as recommended in previous literature 5,12. Initially, all models showed unacceptable and poor fitting models hence illustrated the disagreement between the hypothesized model and the study model. 26 As compared to other tested models, Model 3b which additionally permitting correlated error illustrated reasonably result for both; chi square test [χ 2 /df=2.88]and other fit indices were in agreement with the recommend levels, GFI(0.91) hence indicated close fitting. 22 Given the M- DASS20 is continuous data, RMSEA (0.06) indicated acceptable good fit. 3,15 Hence, Model 3b of three factors M-DASS20, suggest the superiority over the other models. Reliability analysis of the M-DASS20 revealed the following Cronbach s alpha values: depression, six items (α=0.76), anxiety, seven items (α=0.77), stress, seven items (α=0.81) and overall (0.90). When compared to the Cronbach s alpha values in the original study. 27 The present study s Cronbach s alpha values were much lower for the depression (α=0.88), anxiety (α=0.82), stress subscale (α=0.90) and the total scale (α=0.93). It has been shown that a small number of items in the construct validation will reduce the Cronbach s alpha values 1. Similarly, the current study also obtained lower Cronbach s alpha values, as compared to Crawford & Henry(2003) 28 for depression (α=0.95), anxiety(α=0.90) and the stress subscale (α=0.93) and the total scale (α=0.97). However, all subscale showed slightly higher values; depression (α=0.75), anxiety(α=0.74) and stress (α=0.79) in comparison to the local findings using the Malay version of DASS21 6,7 ; nevertheless, the present study yielded a similar value for Cronbach s α total (0.90). The Cronbach s α coefficient values were in the range similar to those documented among nurses in Ghana ( ) 29. There is no absolute criterion for the reliability of the instrument; however, a cut-off of 0.70, indicating adequate internal consistency 30 of the observed variables. As non-clinical sample is concerned, the DASS Manual suggested the scores to be calculated and categorized into normal verses emotional distress rather than using the median value as the referral point 1. The mean (SD) scores in the present study using M-DASS20 were as follows: subscale depression [3.12(2.66)], anxiety [5.84(3.62)], and stress [8.00(3.82)]. Similar in Henry & Crawford (2005) 5, Kolmogorov Smirnov tests, showed obtained scores was significantly deviated from a normal distribution. The findings were slightly lower than those in the original version 1 for subscale depression [6.34(6.97)] and subscale stress [10.26(7.91)] but greater to subscale anxiety [4.70(4.71)], and to the findings by Crawford & Henry (2003) 28,for subscale depression [5.55(7.48)], subscale stress [9.27(8.04)] and for subscale anxiety [3.56(5.39)]. Only 4.2% of the participants self perceived have stress, lower than other studies among nurses 19.23% 31, and 23.8% 32 respectively. 3.1% have self-identified themselves suffered of depression far better than

7 115 findings among Iranian nurses which found a prevalence of 25% 32. On the other hand, 31.1% of the nurses self-reported experienced anxiety, higher than Iranian nurses in which reported prevalence of 28%. 32 Nonetheless, the study was self-reported; the outcome might have possibly portrayed response bias, and although the questionnaire is well translated the participants still have given socially desirable answers. 33 The positive correlation value between subscales indicated that there was a positive relationship between the variables. Correlations between subscales obtained in the present study were highly significant and moderate (0.67 to 0.73). Anxiety subscale was more closely associated (0.73) with stress subscales than with depression (0.67), whereas the correlation between depression, and anxiety yielded In comparison to a local study using M-DASS21 6,7, the reported values were slightly higher (0.41 to 0.68);similarly in Lovibond & Lovibond (1995) 27 which documented moderate correlations between subscales (0.54 to 0.65). This finding illustrated that the depressive nurses may also experience anxiety and stress symptoms. These findings supported the hypothesized model of a 3-factor construct of the M-DASS21 and M-DASS20 with moderate inter-correlation between the three subscales (depression, anxiety, and stress). Conclusions In conclusion, the cultural and language differences may possibly have influenced individuals understanding and interpretation of the study items 12. However, the present research has provided preliminary evidence of a valid and reliable M-DASS20 with good psychometric properties among the nursing population in the Klang Valley and has potential for further refinement in the future. Competing interests: None Authors' contributions Nur Azma, BA: Conception and design, Data collection and analysis, drafting article and final approval Rusli, BN: Conception and design of the study, interpretation, drafting and final approval Quek, KF: Conception and design of the study, interpretation, drafting and final approval RM, Noah: Conception and design of the study, drafting and final approval Acknowledgement: The authors would like to acknowledge, with gratitude financial support from the seed grant of the Jeffrey Cheah School of Medicine and Health Sciences, Monash University Sunway campus (TSJC-118a), and the Short Term Research Grant (STR12020) of the University of Kuala Lumpur. We appreciate the support from the Ministry of Health, Malaysia for granting permission to conduct this study. Special thanks to the Chief Matrons at the respective participating hospitals and also staff nurses for their valuable support and contribution. References 1. Lovibond, P. F. & Lovibond S. Manual for the Depression Anxiety Stress Scales. Sydney, Australia: School of Psychology, University of New South Wales; 1995.

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10 118 Table 1: Socio-demographic characteristics of respondents (N=453) Variables Frequency (%) Mean (SD) Age (yr) (18.0) 286(62.9) 78(17.1) 9( 2.0) 30.62(5.56) Race Malay Chinese Indian Other Marital status Not married Married Duration of employment as nurses (yr) Working hours/day (hr) Working hours/week (hr) (93.6) 8 (1.8) 16(3.5) 5(1.1) 107 (23.5) 348 (76.5) 203 (44.8) 126 (27.8) 96 (21.1) 28 (6.2) 404 (89.2) 49(10.8) 21(4.6) 384(84.8) 48(10.6) 7.34(5.16) 7.56(0.91) 45.17(5.80) Household income (RM) ( )

11 119 Subscale Depression Items Table 2: Exploratory Factor Analysis: M-DASS20 (N=453) Factors Q5: attaining initiative 0.78 Q10: nothing to look forward to 0.72 Q13: downhearted and blue 0.61 Q16: unable to become enthusiastic 0.73 Q17: panicking many times 0.71 Q21: meaningless 0.53 Anxiety Q2 : dryness of my mouth 0.59 Q4: breathing difficulties 0.57 Q7: trembling (e.g. hands shaking) 0.52 Q9: panic and make a fool Q15:close to panic Q19: action of heart Q20: scared Stress Q1: hard to wind down 0.76 Q6: overreact 0.63 Q8: nervous energy 0.58 Q11 : getting agitated 0.80 Q12: difficult to relax 0.73 Q14: impatient 0.67 Q18: touchy Table 3: Item total correlations and Cronbach s alpha coefficients for M-DASS20 (N=453) Subscale Item Depression Q5: attaining initiative Q10: nothing to look forward to Q13: downhearted and blue Q16: unable to become enthusiastic Q17: panicking many times Q21: meaningless Anxiety Q2 : dryness of my mouth Q4: breathing difficulties Q7: trembling (e.g. hands shaking) Q9: panic and make a fool Q15:close to panic Q19: action of heart Q20: scared Stress Q1: hard to wind down Q6: overreact Q8: nervous energy Q11 : getting agitated Q12: difficult to relax Q14: impatient Q18: touchy Corrected item total correlation Cronbach s alpha

12 120 Subscales Median (IQR) Table 4: Summary statistics and normative data of M-DASS20 (N=453) Mean (SD) Normal (0-78 a ) Percentage in each DASS category (%) Mild Moderate Severe (79-87) (88-95) (96-98) Very Severe (99-100) M-DASS (2.66) Depression (3.00) M-DASS (3.62) Anxiety (4.00) M-DASS (3.82) Stress (4.00) M-DASS20- Total (9.03) (11.00) Note:: a Percentiles cut-offs corresponding to each DASS category 1 Table 5: Fit Indices for CFA Models of M-DASS21 and M-DASS20 Model* χ 2 df χ 2 /df GFI CFI RMSEA Model 1a Model 1b Model 2a Model 2b Model 3a Model 3b Model 4a Model 4b * Model 1 and 2: M-DASS21; Model 3 and 4: M-DASS20 χ 2 : p<.001. χ 2 : chi square, GFI: Goodness of fit Index, CFI: Comparative Fit Index, RMSEA: Root Mean Square Error of Approximation..