DASS-21: assessment of psychological distress through the Bifactor Model and item analysis

Abstract The term distress has been used to refer to a continuous variable operationalized through symptoms of depression, anxiety, and stress. In this study, psychological distress is measured using the Depression, Anxiety, and Stress Scale (DASS-21). Confirmatory Factor Analysis compared the fit of different measurement models for the DASS-21, with the parameters of the items verified through the Andrich rating scale model. A non-clinical sample of 530 participants (mean age=24.35±6.55 years; 71.89% women) responded to the instrument. According to the theoretical hypothesis, the results indicated a better fit for the bifactor model, composed of three specific factors (depression, anxiety, and stress) and a general factor (general psychological distress). The assessment of the item properties allowed for a better understanding of the organization of the continuum represented by the construct psychological distress. It is possible to conclude that the Brazilian version of the DASS-21 is an adequate measure for psychological distress.