Assessment of the Validity of the Post-Traumatic Stress Disorder Checklist for DSM-5 Scale for Post-Traumatic Stress Disorder Screening in a Cohort of Non-Native French Speaking Soldiers From the Foreign Legion: A Prospective Analysis.

Introduction: Post-traumatic stress disorder (PTSD) is a multifaceted psychiatric disorder arising from exposure to traumatic events, characterized by intrusion symptoms, avoidance behaviors, heightened arousal, and negative cognitive and mood alterations. Military personnel are particularly vulnerable to PTSD because of frequent exposure to life-threatening situations during deployments. In France, studies have reported PTSD prevalence rates of 1.7% and 4.8% among military personnel. Early detection and intervention through regular psychological assessments are essential, as chronic PTSD offers limited therapeutic options. The PTSD Checklist for DSM-5 (PCL-5) is widely used for screening, with demonstrated validity in various settings, including the military. However, its application among non-native French speakers in the French Foreign Legion requires validation as a result of potential comprehension issues.

Materials and methods: This study assessed the psychometric properties of the French version of the PCL-5 in a cohort of French Foreign Legion soldiers deployed in Mali during Operation Barkhane in early 2022. The PCL-5 was administered approximately 1 month postdeployment. Two commonly accepted PCL-5 cutoff scores, 31 and 33, and 4 subscores were used based on recommendations. French proficiency levels were categorized into 5 levels based on validated oral and written examinations. Descriptive statistics, Spearman's correlation coefficients, analysis of variance, and the Kruskal-Wallis test were utilized to analyze the data.

Results: The final sample comprised 250 legionnaires. The mean PCL-5 score was 21.24 (SD=5.23). Six individuals scored above the cutoff; however, after clinical examination, only one was diagnosed with PTSD (prevalence rate of 0.40%), while the others had anxiety or interpersonal issues. The PCL-5 demonstrated excellent internal consistency (Cronbach's alpha=0.96). Subscale internal consistency ranged from 0.60 to 0.93. No significant correlation was found between PCL-5 scores and French proficiency levels.

Discussion: This study confirms the reliability of the PCL-5 as a PTSD screening tool within the French Foreign Legion, demonstrating strong internal consistency and applicability across diverse linguistic backgrounds. The high sensitivity of the PCL-5 resulted in false positives, underscoring the necessity of follow-up clinical evaluations to confirm PTSD diagnoses and provide appropriate care. The lack of significant correlations between PCL-5 scores and French proficiency suggests the tool effectively screens individuals regardless of language proficiency. Future research should aim to enhance item comprehension among non-native speakers and explore additional screening instruments to complement the PCL-5 in this unique linguistic population.

Clinical trial registration: 20230928_C2EDFRI_4.