Factor structure of the depression anxiety stress Scale-21 (DASS-21): Unidimensionality of the Arabic version among Egyptian drug users

Background: Emotional distress is common among illicit drug users, and it can negatively affect treatment outcomes and increase the risk of relapse. Nonetheless, instruments that properly measure emotional distress are lacking. Therefore, this study investigated the factor structure of the Arabic Depression Anxiety Stress Scale-21 (DASS-21) in that population. Methods: The DASS-21 and the Self-stigma of Alcohol Dependence Scale (SSAD) were completed by 149 inpatient Egyptian drug users. The DASS-21 was examined using exploratory factor analysis, partial confirmatory factor analysis, and parallel analysis. For validation testing, correlations between stigma scores and DASS scores were computed. Results: A one-factor solution provided the best fit to the DASS-21 data. Four items with low loadings were removed. The resulting DASS-17 was also unidimensional, and its reliability was high (0.88). On the validation tests, the DASS scores correlated with the stigma scores as hypothesized. Conclusion: Subscales of the Arabic version of the DASS-21 do not differentiate between depression and anxiety. A modified 17-item version (the DASS-17) was suitable for measuring overall distress, and the results of convergent validation testing indicated that it was superior to the DASS-21.