Exploring the Gold-Standard: Evidence for a Two-Factor Model of the Clinician Administered PTSD Scale for the DSM-5

Objective: The latent factor structure of posttraumatic stress disorder (PTSD) remains a source of considerable variability. The current study compared several a priori factor structures, as well as a novel 2-factor structure of posttraumatic psychological distress as measured by the Clinician Administered PTSD scale for the DSM-5 (CAPS-5). In addition, variability in diagnostic rates according to the divergent DSM-5 and ICD-11 criteria were explored. Method: The setting for this study was a Level 1 trauma center in a U.S. metropolitan city. Data were pooled from 2 studies (N = 309) and participants were administered the CAPS-5 at 1 (n = 139) or 6 months postinjury (n = 170). Confirmatory factor analysis (CFA) was used to compare several factor models, and prevalence rates based on DSM-5 and ICD-11 criteria were compared via z tests and kappa. Results: CFAs of 5 factor structures indicated good fit for all models. A novel 2-factor model based on competing models of PTSD symptoms and modification indices was then tested. The 2-factor model of the CAPS-5 performed as well or better on most indices compared to a 7-factor hybrid. Comparisons of PTSD prevalence rates found no significant differences, but agreement was variable. Conclusions: These findings indicate that the CAPS-5 can be seen as measuring 2 distinct phenomena: posttraumatic stress disorder and general posttraumatic dysphoria. This is an important contribution to the current debate on which latent factors constitute PTSD and may reduce discordance.