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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 BA1, 2*, Rusli BN 1, Quek KF 1, RM Noah 2 1
2
Jeffrey Cheah School of Medicine and Health Sciences, Monash University, Malaysia 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, 47500 Sunway, Selangor, Malaysia Tel: +603-55146300 | Email:
[email protected]
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 symptoms1. Subsequently, a shorter version (DASS-21) consisting of 21 items was
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International Journal of Collaborative Research on Internal Medicine & Public Health 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 states2, 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 Australia4, England5, and Canada2 and was translated into several local languages including Bahasa Malaysia6–8, Spanish9 and Chinese10 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 studies6. 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,’
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International Journal of Collaborative Research on Internal Medicine & Public Health ‘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 disorder1.
Statistical Analysis Data entry and analysis were undertaken using the IBM SPSS Statistics Version 20.0. 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 items6,7,11; 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 (p1) 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 0.80. For the second factor (F2), M-DASS21-Anxiety subscale, items loading 0.52 to 0.78. The M-DASS21 Depression subscale left with six items in factor 3 (F3) with all items loading 0.53-0.78. The final validated Malay version of M-DASS21 (MDASS20) is shown in Table 2.
Reliability Table 3 shows the item-total correlations and Cronbach’s alpha coefficients for M–DASS20Depression, (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 (0.41 – 0.72), thereby supporting the high Cronbach’s alpha coefficients and suggesting good internal consistencies.
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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 0.73. 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 MDASS21 and M-DASS20 uses four fit indices: chi-square (χ2), 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 retesting25. 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 χ2 [χ2 (186) =617.83, P
