Improving the accuracy of the Posttraumatic Stress Disorder Checklist (PCL-5) and Life Events Checklist (LEC-5) as diagnostic tools for posttraumatic stress disorder.

The large impact and sequelae of posttraumatic stress disorder (PTSD) place the development of accurate assessment tools a top priority. The latest version of the PTSD Checklist (PCL-5) is commonly administered in conjunction with the Life Events Checklist (LEC-5) to categorize a person as having or not having PTSD. Despite this being a common approach, researchers have yet to investigate to what degree this approach can lead to false positive PTSD identification, given the broad range of stressful events respondents could be considering while answering the questionnaires. The goal of this study was to evaluate the false positive rate of the PCL-5/LEC-5 combination. A battery of questionnaires was administered to a large sample of college students (N = 864) that contained the PCL-5, the LEC-5, and an assessment of the stressful event the participant was thinking about while answering the PCL-5 questionnaire. The specificity obtained by the PCL-5/LEC-5 combination was 0.86. Concretely, our results show that among the potential positives (n = 184), more than the 58% (n = 107) were considered false positives, whereas only 41.84% (n = 77) were assessed as true positives. The addition of a single item asking participants what they were thinking about while answering the PCL-5 questionnaire was able to successfully identify these cases, as evidenced by the obtainment of similar rates than more time-consuming and clinician-administered measures. The results of this study lead to questions about the generalizability of several findings reported in the PTSD literature. (PsycInfo Database Record (c) 2025 APA, all rights reserved).