Validation of the Death and Dying Distress Scale in patients with advanced cancer
Gilla K. Shapiro, Kenneth Mah, Madeline Li, Camilla Zimmermann, Sarah Hales, Gary Rodin
Abstract
BACKGROUND: Distress about dying and death is an important clinical and research outcome in advanced cancer. A 15-item Death and Dying Distress Scale (DADDS) measure has undergone preliminary validation, but full validation in a large sample has not previously been reported. We investigated its psychometric characteristics and responsiveness to a therapeutic intervention. METHODS: This is a secondary analysis of baseline data obtained from a randomized controlled trial of psychotherapeutic intervention for patients with advanced cancer. Participants (n = 386) completed the DADDS, and measures of depression, anxiety, demoralization, quality of life (including preparation for end of life), spirituality, attachment security, and symptom burden. RESULTS: A confirmatory factor analysis revealed factors related to "Finitude" and to "Dying." Both factors showed good internal consistency (Cronbach α = 0.861-0.949). DADDS scores were significantly higher in females, those with lower income and not working. Construct validity was demonstrated by a positive correlation between DADDS and demoralization (r = 0.569-0.679), and a negative correlation with preparation for the end of life (r = -0.475 to -0.678). At 6 months, intervention participants with moderate DADDS scores at baseline reported significantly lower DADDS scores on both factors compared to usual care. CONCLUSIONS: The DADDS is a valid and brief two-factor measure that assesses distress related to the shortness of time and to the process of dying. The total and factor scores have utility in the clinical and research assessment of death-related distress in patients with advanced cancer.