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UBC Theses and Dissertations

Measurement of Post Traumatic Stress Disorder : an a posteriori content validation of the clinician-administered PTSD scale (CAPS-dxsx) Thiessen, Lynda Gail


Many people in society today suffer from the consequences of exposure to a traumatic event in their life of the life of a loved one. These persons are at risk for developing a condition known as Post Traumatic Stress Disorder (PTSD). PTSD is a potentially debilitating disorder that is characterized by three symptoms clusters: reexperiencing, numbing and avoidance, and hyperarousal. To assess PTSD, many practitioners often use semi-structured interviews. The current "gold-standard" instrument for assessing PTSD is the Clinician-Administered Post Traumatic Stress Scale (CAPS; Blake et al., 1995). However, the CAPS has gaps in its validity evidence. In particular, a content validation study has not been performed to assess the ability of the CAPS to produce content-related validity evidence. The purpose of the present study was to evaluate (a) the CAPS adequacy in sampling the entire content domain of PTSD (b) how relevant each of the elements of the CAPS was, and (c) whether our current definitions of trauma and PTSD in the DSM-IV-TR (APA, 2000) are considered adequate by our subject matter experts. Results indicated that the CAPS received high ratings for the relevance of its traumatic events questions, individual items, and Life Events Checklist; however, it received poor ratings for its format, rating scales, global ratings, associated features, time-sampling parameter, scoring and summary chart, and summary sheet. Moreover, the CAPS failed to achieve minimum acceptable levels for its representativeness for the content domain of PTSD. Concordantly, subject-matter experts rated the current definition of PTSD in the DSM-IV-TR (2000) as inadequate. Experts indicated that the current conceptualization of PTSD does not capture the full range of symptoms seen in clients with PTSD. Implications and suggestions for future research are proposed.

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