Posttraumatic stress disorder (PTSD) is commonly assessed with self-rated or clinician-rated measures. Although scores from these assessment modalities are strongly associated, they are often discrepant for individual symptoms, total symptom severity, and diagnostic status. To date, no known studies have empirically identified the sources of these discrepancies. In the present study, we had three aims: (a) replicate previously identified discrepancies; (b) examine contribution of possible objective predictors of discrepancies, including negative response bias, random responding, conscientiousness, neuroticism, and verbal IQ; and (c) identify subjective sources of discrepancies through analysis of participant feedback. Trauma-exposed undergraduates (N = 60) were administered the PTSD Checklist for DSM-5 (PCL-5), the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5), and other questionnaires. Interviewers identified discrepancies between corresponding PCL-5/CAPS-5 scores and asked participants to describe their attributions for discrepancies. Discrepancies, both dimensional and dichotomous, occurred at the item, cluster, and total score level. Objective predictors were weakly associated with discrepancies. The most commonly reported reasons for discrepancies were time-frame reminders, comprehension of symptoms, trauma-related attribution errors, increased awareness, and general errors. These findings help explain discordance between the PCL-5 and CAPS-5, and inform use and interpretation of these two widely used PTSD measures in clinical and research applications.
Keywords: Clinician-Administered PTSD Scale for DSM-5; PTSD Checklist for DSM-5; assessment; discrepancies; posttraumatic stress disorder.