Comparison of the PTSD symptom scale–interview version and the clinician‐administered PTSD scale

Abstract

The Clinician‐Administered PTSD Scale (CAPS) is one of the most frequently used measures of posttraumatic stress disorder (PTSD). It has been shown to be a reliable and valid measure, although its psychometric properties in nonveteran populations are not well known. One problem with the CAPS is its long assessment time. The PTSD Symptom Scale–Interview Version (PSS‐I) is an alternative measure of PTSD severity, requiring less assessment time than the CAPS. Preliminary studies indicate that the PSS‐I is reliable and valid in civilian trauma survivors. In the present study we compared the psychometric properties of the CAPS and the PSS‐I in a sample of 64 civilian trauma survivors with and without PTSD. Participants were administered the CAPS, the PSS‐I, and the Structured Clinical Interview for DSM‐IV (SCID) by separate interviewers, and their responses were videotaped and rated by independent clinicians. Results indicated that the CAPS and the PSS‐I showed high internal consistency, with no differences between the two measures. Interrater reliability was also high for both measures, with the PSS‐I yielding a slightly higher coefficient. The CAPS and the PSS‐I correlated strongly with each other and with the SCID. Although the CAPS had slightly higher specificity and the PSS‐I had slightly higher sensitivity to PTSD, overall the CAPS and the PSS‐I performed about equally well. These results suggest that the PSS‐I can be used instead of the CAPS in the assessment of PTSD, thus decreasing assessment time without sacrificing reliability or validity.