The German PCL-5 : evaluating structural validity in a large-scale sample of the general German population

Background: In attempts to elucidate PTSD, recent factor analytic studies resulted in complex models with a proliferating number of factors that lack psychometrical and clinical utility. Recently, suggestions have been made to optimize factor analytic practices to meet a refined set of statistical and psychometric criteria.

Objective: This study aims to assess the factorial structure of the German version of the PCL-5, implementing recent methodological advancements to address the risk of overfitting models. In doing so we diverge from traditional factor analytical research on PTSD.

Method: On a large-scale sample of the German general population (n = 1625), exploratory factor analyses were run to investigate the dimensionality found within the data. Subsequently, we validated and compared all model suggestions from our preliminary analyses plus all standard and common alternative PTSD factor models (including the ICD-11 model) from previous literature with confirmatory factor analyses. We not only consider model fit indices based on WLSMV estimation but also deploy criteria such as favouring less complex models with a parsimonious number of factors, sufficient items per factor, low inter-factor correlations and number of model misspecifications.

Results: All tested models showed adequate to excellent fit in respect to traditional model fit indices; however, models with two or more factors increasingly failed to meet other statistical and psychometric criteria.

Conclusion: Based on the results we favour a two-factor bifactor model with a strong general PTSD factor and two less dominant specific factors – one factor with trauma-related symptoms (re-experiencing and avoidance) and one factor with global psychological symptoms (describing the trauma’s higher-order impact on mood, cognition, behaviour and arousal).

From the perspective of clinical utility, we recommend the cut-off scoring method for the German version of the PCL-5. Basic psychometric properties and scale characteristics are provided.

HIGHLIGHTS

• We contribute new insights to the debate on the factor structure of the PTSD Checklist (PCL-5) based on a large German general population sample deploying the newest methodological developments in a revised factor-analytical approach.
• Combining theoretical, statistical and practical considerations, we favour a two-factor bifactor model with a strong general PTSD factor and two less dominant specific factors – one factor with trauma-related symptoms and one factor with global psychological symptoms.
• For clinical practitioners, we recommend using the cut-off scoring method.