Factor structure and validity of the Depression, Anxiety and Stress Scale-21 in Swedish translation

Abstract

WHAT IS KNOWN ON THE SUBJECT?: The Depression, Anxiety and Stress Scale-21 (DASS-21) is a widely used measurement for psychological symptoms and distress. Some previous studies have shown that the DASS-21 can accurately measure symptoms of anxiety, depression and stress, while other studies have indicated that the DASS-21 mainly measures overall distress. The factor structure of the DASS-21 is important and debated since if affects interpretations of findings. WHAT DOES THIS PAPER ADD TO EXISTING KNOWLEDGE?: In this study, the DASS-21 was translated into Swedish and evaluated in three diverse samples. The DASS-21 subscales of Depression and Anxiety correlated significantly with corresponding criteria instruments. The DASS-21 Stress subscale showed more diverse associations with psychological distress. The analyses supported a bifactor model of the DASS-21 with three specific factors of depression, anxiety and stress as well as a general distress factor. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: The results show that the DASS-21 may be used to measure unique symptoms of depression, anxiety and, with some caveat, stress as well as overall psychological distress. This study confirms that the DASS-21 is theoretically sound instrument that is feasible for both research and clinical practice. The DASS-21 can be an accessible tool for screening and evaluation in first-line mental health services.

Abstract: Introduction There is a constant need for theoretically sound and valid self-report instruments for measuring psychological distress. Previous studies have shown that the Depression, Anxiety and Stress Scale-21 (DASS-21) is theoretically sound, but there have been some inconsistent results regarding its factor structure. Aims The aim of the present study was to investigate and elucidate the factor structure and convergent validity of the DASS-21. Methods A total of 624 participants recruited from student, primary care and psychotherapy populations. The factor structure of the DASS-21 was assessed by confirmatory factor analyses and the convergent validity by investigating its unique correlations with other psychiatric instruments. Results A bifactor structure with depression, anxiety, stress and a general factor provided the best fit indices for the DASS-21. The convergent validity was adequate for the Depression and Anxiety subscales but more ambiguous for the Stress subscale. Discussion The present study overall supports the validity and factor structure of the DASS-21. Implications for practice The DASS-21 can be used to measure symptoms of depression and anxiety as well as overall distress. It can be useful for mental health nurses, and other first-line psychiatric professionals, in need of a short, feasible and valid instrument in everyday care.

Keywords: anxiety; depression; distress; psychometric; screening; stress.