Psychometric comparison of the generalized anxiety disorder scale-7 and the Penn State Worry Questionnaire for measuring response during treatment of generalised anxiety disorder.

The Penn State Worry Questionnaire (PSWQ) is a widely used measure of the worry characteristic of generalised anxiety disorder (GAD). The 7-item Generalized Anxiety Disorder Scale (GAD-7) is a new brief screening tool for GAD, which is being increasingly used in research and clinical practice. The present study sought to provide comparison data on the relative psychometric properties of these two scales. The data of 195 adults who met Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for GAD and who participated in two randomised treatment controlled trials were used. Factor analyses, internal consistency, correlational analyses, responsiveness to change, and agreement between the scales based on indentified clinical cutoffs were conducted. Factor analyses confirmed a one-factor structure for the GAD-7 and a three-factor structure involving two method factors for the PSWQ. Both the GAD-7 and the PSWQ demonstrated adequate internal consistency (Cronbach's alpha: .79-.91 and .86-.91, respectively), and moderate correlations (r = .51-.71) were observed between the scales across the treatment time points. The scales exhibited small correlations with the Sheehan Disability Scale at pretreatment (GAD-7 r = .38; PSWQ r = .26), but moderate correlations at posttreatment and follow-up (r = .59-.79). Agreement between the scales was limited using various clinical cutoffs identified within the literature. Both measures were sensitive to change, although the GAD-7 appeared to be more sensitive and may, therefore, confer some advantages in clinical work.