Evaluating depression, anxiety, and stress assessment before and during the COVID-19 pandemic using Generalisability Theory

Abstract

The evaluation of depression, anxiety, and stress requires distinguishing between state and trait changes. Otherwise, the accuracy of evaluating the effectiveness of interventions and the reliability and validity of research can be compromised. The COVID-19 pandemic has introduced extraneous variables that have the potential to significantly impact the measurement of affective conditions and the distinction between state or trait symptoms. The Depression Anxiety and Stress Scales (DASS-21) is the only psychometric scale that measures depression, anxiety, and stress, and the overall psychological distress simultaneously. It is widely used and applicable to both clinical and non-clinical populations. However, no study has assessed its ability to distinguish state from trait changes or investigated the impact of the COVID-19 pandemic on its temporal reliability. In this study, Generalisability Theory (G-Theory) was applied to evaluate the DASS-21 under normal and COVID-19 pandemic conditions. Data was collected from two independent samples. The first sample was collected in the United States (n = 115) before the pandemic and the second sample was collected in New Zealand (n = 114) during the pandemic. In both samples the data were collected on three occasions with 2 to 4-week intervals. The total DASS-21 scale showed excellent reliability in measuring enduring symptoms of psychological distress (G = 0.94 to 0.96), and while all DASS-21 subscales demonstrated good reliability in the pre-pandemic US sample, they showed lower temporal reliability in the NZ sample during the pandemic. These findings suggest that the overall DASS-21 reliably measures psychological distress as a trait and its scores can be generalised across different populations and occasions. However, the DASS-21 subscales are not as reliable during emergencies and uncertainty as seen in the COVID-19 pandemic. The overall psychological distress remains stable across individuals and can be reliably measured by the DASS-21, but shifts in depression, anxiety, and stress levels are likely during emergencies and uncertainty.