Description
The PDSS is a self report scale that provides operationalized ratings of DSM-IV panic disorder symptoms. The PDSS consists of seven items, each rated on a 5-point scale. The items are carefully anchored and assess panic frequency, distress during panic, panic-focused anticipatory anxiety, phobic avoidance of situations, phobic avoidance of physical sensations, impairment in work functioning, and impairment in social functioning. The scale can be administered in 5-10 minutes. It is a useful way of assessing overall panic disorder severity at baseline, and it provides a profile of severity of the different panic disorder symptoms. It is a good monitoring tool because it is brief and sensitive to change. This scale is meant for use after diagnosis.

Validity
Evaluation of internal consistency in 198 patients with DSM-III-R panic disorder yielded a Cronbach’s alpha of 0.64. Joint reliability ranged from 0.84 to 0.88 for trained raters. The PDSS total score showed moderate correlations with both panic disorder severity ratings of the Anxiety Disorders Interview Schedule-Revised (ADIS-R) (r = 0.54) (DiNardo and Barlow 1988) and severity ratings of the Clinical Global Impression (CGI) Scale (r = 0.66). Individual PDSS item scores were strongly associated (r = 0.60-0.78) with ADIS-R items of similar content and less strongly associated (r = 0.35-0.47) with CGI Scale and ADIS-R severity ratings. The PDSS items most highly correlated with similar ADIS-R items were panic frequency (r = 0.71), anticipatory anxiety (r = 0.78), agoraphobic fear and avoidance (r = 0.73), and sensation fear and avoidance (r = 0.69). The PDSS total score was not significantly correlated with that of the Hamilton Rating Scale for Depression (Ham-D) (r = 0.11). The PDSS has proved to be sensitive to change with treatment.

Interpretation
In scoring the Panic Disorder Severity Scale, items are rated on a scale of 0 to 4. A composite score is established by averaging the scores of the seven items. This composite score indicates, on average, how the test taker responded to each question, higher scores indicating a higher severity of panic disorder. Raw scores range from 0 to 28 and composite scores range from 0-4. This test is not diagnostic; however a score of 9 and above suggest the need for a formal diagnostic assessment. Scores are sensitive to change after psychological treatment.

Developer
Shear, M.K., Brown, T.A., Barlow, D.H., Money, R., Sholomskas, D.E., Woods, S.W., Gorman, J.M., Papp, L.A. (1997). Multicenter collaborative Panic Disorder Severity Scale. American Journal of Psychiatry, 154, 1571-1575.