Psychometric properties of the German version of the Traumatic Grief Inventory-Self Report Plus (TGI-SR+)

Background: Prolonged Grief Disorder (PGD) has been recognized as a mental health disorder and was added to the ICD-11 and DSM-5-TR. Despite the same name, both versions of PGD differ in symptom count, content, and diagnostic algorithm. A single instrument to screen for both PGD diagnoses is critical for bereavement research and care. The study aimed to evaluate the psychometric properties of the German version of the Traumatic Grief Inventory Self-Report Plus (TGI-SR+), a self-report measure to assess PGD_ICD-11 and PGD_DSM-5-TR symptoms.Methods: Out of a representative sample of the German general population (N = 2509), 1062 reported a significant loss and completed questions about sociodemographic and loss-related variables, the TGI-SR+, and a measure of health-related quality of life.Results: Item analyses demonstrated good item characteristics. Confirmatory factor analyses showed a good fit for two-factor models for PGD_ICD-11 and PGD_DSM-5-TR. Omega values demonstrated good internal consistency. In support of concurrent validity, symptoms of PGD_ICD-11 and PGD_DSM-5-TR were associated with worse health-related quality of life. In support of known-groups validity, symptoms of PGD_ICD-11 and PGD_DSM-5-TR were significantly higher among women, people with a lower educational level, more recently bereaved, those who lost a spouse or child (vs. other person), and those who lost someone due to unnatural causes (vs. natural causes). ROC analyses showed optimal cut-off scores of ≥60 and ≥65 to screen for probable caseness for PGD_ICD-11 and PGD_DSM-5-TR, respectively.Limitations: The analyses were based on a cross-sectional design, and data on retest-reliability and predictive validity is missing.Conclusion: Results support the reliability and validity of the German TGI-SR+ as a screening instrument for PGD in research.