Background: Complicated grief, which is often under-recognized and under-treated, can lead to substantial impairment in functioning. The Brief Grief Questionnaire (BGQ) is a 5-item self-report or interview instrument for screening complicated grief. Although investigations with help-seeking samples suggest that the BGQ is valid and reliable, it has not been validated in a broader population. Methodology/Principal Findings: A questionnaire was mailed to a randomly selected sample (n = 5000) residing in one of 4 areas of Japan. The BCQ was examined for responders who were bereaved more than 6 months and less than 10 years (n = 915). Non-specific psychological distress was assessed with the K6 screening scale. Multiple group confirmatory factor analysis supported a uni-dimensional factor structure and the invariance of parameters across gender and age. Cronbach's alpha was sufficiently high (alpha =. 75) to confirm internal consistency. Average Variance Extracted (0.39) was higher than the shared covariance (0.14) between BGQ and K6, suggesting discriminant validity. Conclusions: The results of this study support the reliability and validity of the BGQ in the Japanese population. Future studies should examine predictive validity by using structured interviews or more detailed scales for complicated grief.
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