A Bifactor Evaluation of Self-Report and Clinician-Administered Measures of PTSD in Veterans

The PTSD Checklist for DSM-5 (PCL-5) and the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) are two of the most widely used and well-validated PTSD measures providing total and subscale scores that correspond with DSM-5 PTSD symptoms. However, there is little information about the utility of subscale scores above and beyond the total score for either measure. The current study compared the proposed DSM-5 four-factor model to a bifactor model across both measures using a sample of veterans (N = 1,240) presenting to a Veterans Affairs (VA) PTSD specialty clinic. The correlated factors and bifactor models for both measures evidenced marginal-to-acceptable fit and were retained for further evaluation. Bifactor specific indices suggested that both measures exhibited a strong general factor but weak lower-order factors. Structural regressions revealed that most of the lower-order factors provided little utility in predicting relevant outcomes. Although additional research is needed to make definitive statements about the utility of PCL-5 and CAPS-5 subscales, study findings point to numerous weaknesses. As such, caution should be exercised when using or interpreting subscale scores in future research.