Validation of the Japanese version of the death and dying distress scale

The Death and Dying Distress Scale (DADDS) is a self-report instrument used to assess distress related to dying and death in patients with advanced cancer. We aimed to test the reliability and validity of the Japanese-translated version of the DADDS (DADDS-J) and evaluate its psychological properties in patients with advanced cancer in Japan.

Japanese participants with advanced cancer (n = 200) completed the DADDS and additional tools measuring depression (Patient Health Questionnaire-9), anxiety (Generalized Anxiety Disorder-7), quality of life (Functional Assessment of Cancer Therapy-General; Japanese Version of the Quality of Life at the End of Life-Cancer Scale), symptom burden (Japanese Version of the Quality of Life at the End of Life-Cancer Scale), and spirituality (Functional Assessment of Chronic Illness Therapy-Spiritual Well-Being). Exploratory factor analysis (EFA), parallel analysis, and confirmatory factor analyses (CFA) were performed on 15 DADDS items. Internal consistency was assessed using Cronbach's alpha and McDonald's ω, and construct validity was examined by calculating correlations with relevant scales.

EFA and parallel analysis identified a three-factor structure in the 14-item DADDS-J after item 3 was excluded, with Cronbach's alpha and McDonald's ω ranging from 0.85 to 0.92. CFA showed an adequate fit for the unique structure. Each subscale was significantly correlated with age, depression, anxiety, symptom burden, and lower quality of life and spirituality, but not with social and family well-being or time since cancer diagnosis.

The DADDS-J has a three-factor structure and demonstrates good reliability and validity. Differences between the original and Japanese versions of the scale may be due to cultural factors. This is the first tool that can measure spiritual pain associated with death in patients with advanced cancer in Japan and is suitable for large-scale studies and clinic use. This scale can enhance research and clinical care for patients with advanced cancer in Japan.