Development and validation of a DSM-5-based generalized anxiety disorder self-report Scale: Investigating frequency and intensity rating differences

Abstract

There are limitations in the currently available measures for the assessment of generalized anxiety disorder (GAD). While changes have been made in the diagnostic criteria for GAD from DSM-IV to DSM-5, there are no scales which items correspond directly to DSM-5-based GAD symptomatology. Moreover, although recent studies support measuring both symptom frequency and intensity of mental disorders, most GAD measures assess only either symptom frequency or intensity, and there is no DSM-5-based self-report measure of GAD that assesses both. In order to address these limitations, two studies were conducted to develop and validate a new GAD self-report scale, the Generalized Anxiety Symptom Severity Inventory (GASSI), which measures symptom severity by assessing both the frequency and intensity of DSM-5-based GAD symptoms in samples of undergraduates and natural disaster survivors. Study 1 provides evidence for a one-factor summed frequency and intensity GAD score using exploratory factor analysis. GASSI was found to have good reliability and evidence of construct validity. Study 2 suggests that both frequency and intensity of symptoms are needed in assessing GAD severity based on the results of invariance testing. These findings have implications for the measurement of GAD symptoms, as well as in the development of interventions for GAD.