Psychometric Properties of the Penn State Worry Questionnaire-Past Week (PSWQ-PW) in an Anxiety and Related Disorders Sample

Worry is a transdiagnostic characteristic across many mental health disorders and given the increased interest and recognized importance of measurement-based care and progress monitoring for mental health treatment, there is a need for psychometrically sound questionnaires that can track weekly progress. The Penn State Worry Questionnaire-Past Week (PSWQ-PW; Stöber & Bittencourt Behaviour Research and Therapy, 36(6), 645–656, 1998) was developed to be sensitive to the assessment of short-term changes in worry severity. This study examined the psychometric properties and treatment sensitivity of the PSWQ-PW in a sample of 370 outpatients with anxiety and related disorders. An exploratory factor analysis indicated that the PSWQ-PW has a one-factor structure measuring the unidimensional construct of worry. The PSWQ-PW demonstrated strong reliability and good convergent validity. However, the PSWQ-PW had poor discriminant validity with a measure of depression and stress, which may be explained by the distinct but related nature of these constructs. Additionally, the PSWQ-PW did not have strong diagnostic potential in identifying individuals with Generalized Anxiety Disorder (GAD) from a heterogeneous clinical sample, likely because of the transdiagnostic nature of worry and the state nature of the measure. Finally, the PSWQ-PW demonstrated strong treatment sensitivity (d = 0.85) when measured weekly across a 12-week cognitive behavioural therapy for GAD protocol. These findings suggest that the PSWQ-PW is a reliable and valid way to track changes in worry severity week-to-week to monitor patient progress throughout treatment. However, it should not be used as a diagnostic or screening measure to distinguish patients with GAD from those with other anxiety and related disorders.