Psychometric analysis of the Swedish panic disorder severity scale and its self-report version

Abstract

Background: Panic disorder, with or without agoraphobia (PDA or PD, respectively), is a major public health problem. After having established a PD diagnosis based on the DSM or the ICD systems, the Panic Disorder Severity Scale (PDSS) is the most widely used interview-based instrument for assessing disorder severity. There is also a self-report version of the instrument (PDSS-SR); both exist in a Swedish translation but their psychometric properties remain untested.

Methods: We studied 221 patients with PD/PDA recruited to a randomized controlled preference trial of cognitive-behavioral and brief panic-focused psychodynamic psychotherapy. In addition to PDSS and PDSS-SR the participants completed self-reports including the Clinical Outcome in Routine Evaluation – Outcome Measure, Montgomery Åsberg Depression Rating Scale, Sheehan Disability Scale, Bodily Sensations Questionnaire and the Mobility Inventory for Agoraphobia.

Results: PDSS and PDSS-SR possessed excellent psychometric properties (internal consistency, test–retest reliability) and convergent validity. A single factor structure for both versions was not confirmed. In terms of clinical utility, the PDSS had very high inter-rater reliability and correspondence with PD assessed via structured diagnostic interview. Both versions were sensitive to the effects of PD-focused treatment, although subjects scored systematically lower on the self-report version.

Conclusions: The study confirmed the reliability and validity of the Swedish versions of PDSS and PDSS-SR. Both versions were highly sensitive to the effects of two PD-focused treatments and can be used both in clinical and research settings. However, further investigation of the factor structures of both the PDSS and PDSS-SR is warranted.

Trial registration: ClinicalTrials.gov identifier: NCT01606592.

Keywords:

• Panic disorder
• assessment
• anxiety
• psychometric properties
• factor analysis

Disclosure statement

No member in the research team declares any conflict of interest.

Note

Notes

1 Unless otherwise specified, the acronym PD is used to refer to individuals with and without a history of agoraphobia.

Additional information

Funding

Project POSE was generously supported by grants from the Swedish Research Council for Health, Working Life, and Welfare; REHSAM/Swedish Social Insurance Agency; L. J. Boëthius’ Foundation; and the Regions of Skåne and Halland. Project POSE have received grants from FORTE, REHSAM, and L.J. Boëthius foundation during the study. In addition to this PhD student Thomas Nilsson has received grants from Region Skåne and PhD student Martin Svensson has received grants from Region Halland. Also fundings were provided by Forskningsrådet om Hälsa, Arbetsliv och Välfärd; L.J. Boëthius´ stiftelse.