We calculated the reliable change index (RCI) and clinically significant change (CSC) values for two widely used measures of posttraumatic stress disorder (PTSD): The Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) and the PTSD Checklist for DSM-5 (PCL-5) and examined how symptom changes at these thresholds related to improvements in psychosocial functioning. We used data from three independent samples of male military veterans, including two randomized controlled trials for PTSD (N = 198 for Sample 1 and N = 102 for Sample 2) and a cross-sectional study of primary care patients (N = 228). For Sample 1, within-person change in CAPS-5 and PCL-5 scores of ≥ 13 and 15, respectively, was indicative of reliable change. For Sample 2, within-person change in CAPS-5 and PCL-5 scores of ≥ 12 and 18, respectively, was indicative of reliable change. Scores of ≤ 8 and 28 on the CAPS-5 and PCL-5, respectively, indicated a participant is more likely to belong to the non-PTSD population than the PTSD population (i.e., clinically significant change) in both Samples 1 and 2. Participants who exhibited reliable or CSC reported significantly better psychosocial functioning at all posttreatment assessments than those who did not. Results provide thresholds for identifying clinically meaningful PTSD symptom change using these measures. Care should be taken to interpret these values appropriately and relative to numerous other definitions for meaningful symptom change. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The aim of this study was to determine optimally efficient cutoff scores on the Posttraumatic Stress Disorder Checklist (PCL) for identifying full posttraumatic stress disorder (PTSD) and partial PTSD (P-PTSD) in active-duty Marines and Sailors. Participants were 1,016 Marines and Sailors who were administered the PCL and Clinician-Administered PTSD Scale (CAPS) 3 months after returning from Operations Iraqi and Enduring Freedom. PCL cutoffs were tested against three CAPS-based classifications: full PTSD, stringent P-PTSD, and lenient P-PTSD. A PCL score of 39 was found to be optimally efficient for identifying full PTSD. Scores of 38 and 33 were found to be optimally efficient for identifying stringent and lenient P-PTSD, respectively. Findings suggest that the PCL cutoff that is optimally efficient for detecting PTSD in active-duty Marines and Sailors is substantially lower than the score of 50 commonly used by researchers. In addition, findings provide scores useful for identifying P-PTSD in returning service members.