The accuracy of the Clinician-Administered PTSD Scale (CAPS) to identify PTSD cases in victims of urban violence

Abstract

As a consequence of the increasing urban violence in Brazil, many cases of posttraumatic stress disorder (PTSD) are now seen in the community and clinical settings. The main aim of this article is to assess the psychometric properties of the Clinician-Administered PTSD Scale (CAPS) to study factors related to the etiology, prognosis, and efficacy of interventions of PTSD in civilian populations. PTSD outpatients from a program of victims of violence and subjects identified in an epidemiological survey conducted in the city of Sao Paulo completed a battery of validated instruments and the CAPS. Instrument reliability and validity were measured. The comparison between the CAPS scores and the Structured Clinical Interview for DSM IV (SCID) interview resulted in the following validity coefficients: sensitivity=90%, specificity=95%, and misclassification rate=7.1%. The area under the receiver operating characteristic (ROC) curve was 0.97. There was a positive correlation between CAPS scores with Beck Depression Inventory (BDI; 0.70) and Beck Anxiety Inventory (BAI; 0.76) scores. The Kappa coefficients were all higher than 0.63 for all CAPS items. The internal consistency for all CAPS items resulted in a Cronbach's alpha coefficient of 0.97. The CAPS showed to be both an accurate and a reliable research instrument to identify PTSD cases in a civilian population.