Detecting Dissociation: Comparing the CAPS-5, SCID-D-R, and MID in Women with PTSD

Abstract
Objective
Pathological dissociative symptoms are central features of trauma-spectrum disorders like posttraumatic stress disorder (PTSD), the dissociative subtype of PTSD (PTSD-D) and complex dissociative disorders. Despite the clinical relevance of dissociation, many clinicians and trauma researchers have limited formal training in dissociation assessment and often rely on the Clinician Administered PTSD Scale for DSM-5 (CAPS-5). The CAPS-5 includes two dissociation items, which we hypothesized may risk false negatives and construct underrepresentation. In this study, we examined the extent to which the CAPS-5 effectively captures dissociation.

Method
Participants were 92 treatment-seeking women with PTSD, the majority of whom had PTSD-D (n = 62). A subset of individuals with PTSD-D had co-occurring complex dissociative disorders (n = 42). Participants completed the CAPS-5, Structured Clinical Interview for DSM-IV Dissociative Disorders-Revised (SCID-D-R), and the Multidimensional Inventory of Dissociation (MID) self-report measure. The research team came to a final diagnostic consensus upon reviewing all assessment scores and clinical impressions, and this diagnosis was used to determine concordant and discrepant results.

Sensitivity and specificity were calculated as percentages with exact Clopper-Pearson confidence intervals based on concordant and discrepant results from each assessment instrument against the final diagnosis using MedCalc. Dissociation prevalence was based on studies of similar populations (United States, outpatient psychiatric settings, women) and used to calculate positive and negative predictive values. For positive or negative predictive values of 0 or 100, the Clopper-Pearson confidence interval was used; otherwise, standard logit confidence intervals were calculated.

Results
The CAPS-5 accurately captured PTSD-D in 60 cases with 7 false negative cases diagnosing PTSD instead of PTSD-D. Forty-two participants had more extensive dissociation that was not detected by the CAPS-5. The MID accurately captured 41 of the 42 individuals with complex dissociative disorders. The SCID-D-R similarly captured 41 individuals with complex dissociative disorders. Overall, the CAPS-5, SCID-D-R, and MID demonstrated acceptable to high sensitivity within this sample.

Conclusion
Our results suggest that the CAPS-5 will identify the majority of individuals with PTSD-D with some risk of a false negative. Without a more comprehensive dissociation assessment, those with complex dissociative disorders will be overlooked. This has serious treatment implications as these conditions require a different treatment course compared to individuals with only PTSD-D. A comprehensive approach to dissociation assessment is needed to prevent misdiagnosis, facilitate accurate identification of treatment modalities, and improve treatment outcomes.