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

Prolonged grief disorder (PGD), recently included in the ICD-11 and DSM-5-TR, can be assessed using the Traumatic Grief Inventory-Self Report Plus (TGI-SR+). This study evaluates the psychometric properties of the Japanese translation of the TGI-SR+ using a survey of Japanese adults (N = 505) who had experienced bereavement more than one year earlier. To assess the severity of prolonged grief, depression, anxiety, and posttraumatic stress, participants completed several instruments. Confirmatory factor analyses supported a one-factor model, and significant positive correlations supported its convergent validity. Higher PGD severity was observed among participants with lower educational levels, loss of first-degree relatives, violent or unnatural losses, and more recent losses. Meanwhile, the receiver operating characteristic analyses yielded optimal cutoff scores for detecting probable PGD caseness using total TGI-SR+ scores of ≥ 74 and ≥ 71. This study confirmed the reliability and validity of the Japanese TGI-SR+ for assessing PGD severity among Japanese adults.