Psychometric Properties of the Posttraumatic Stress Disorder Symptom Scale Interview for DSM-5 (PSSI-5)

Changes to the diagnostic criteria for posttraumatic stress disorder (PTSD) in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) create a need for valid and reliable updated assessment tools. This study examined key psychometric properties (e. g., internal consistency, test-retest reliability, interrater reliability, and convergent and discriminant validity) of the PTSD Symptom Scale Interview for DSM-5 (PSSI-5), a modified version of the PSS-I (PTSD Symptom Scale)-Interview Version for the DSM-IV. Participants were 242 urban community residents, veterans, and college undergraduates, recruited from 3 study sites, who had experienced a DSM-5 Criterion A traumatic event. The PSSI-5 demonstrated good internal consistency (alpha=.89) and test-retest reliability (r =. 87), as well as excellent interrater reliability for the total severity score (intraclass correlation =.98) and interrater agreement for PTSD diagnosis (kappa=.84). The PSSI-5 also demonstrated convergent validity with 3 measures of PTSD (i. e., Clinician-Administered PTSD Scale for DSM-5, Posttraumatic Diagnostic Scale for DSM-5, and PTSD Checklist-Specific Version; all rs >.72) and discriminant validity with the Beck Depression Inventory-II and the State-Trait Anxiety Inventory-Trait scale. Receiver operating characteristic analysis yielded a cutoff score of 23 for identifying a probable PTSD diagnosis. Together, these findings indicate that the PSSI-5 is a valid and reliable instrument for assessing PTSD diagnosis and severity.