Development of a Japanese Version of the Quality of Life at the End of Life-Cancer Scale.

ABSTRACT

CONTEXT The Quality of Life at the End of Life-Cancer Scale (QUAL-EC) is a self-reported instrument to assesses the quality of life of patients with cancer near the end of life. OBJECTIVE: To test the reliability and validity of the QUAL-EC-J, a Japanese translated version of the QUAL-EC. METHODS: A total of 179 Japanese patients with advanced cancer completed the QUAL-EC-J, Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, Rosenberg Self-Esteem Scale, Multidimensional Scale of Perceived Social Support, Functional Assessment of Cancer Therapy-General Scale, and Functional Assessment of Chronic Illness Therapy-Spiritual questionnaires. We performed confirmatory factor analysis of the four structures of the QUAL-EC and exploratory factor analysis of the QUAL-EC-J. Internal consistency was assessed using Cronbach's α coefficient and validity was examined by calculating correlations with relevant scales. RESULTS: Confirmatory factor analysis showed an inadequate fit to the original QUAL-EC structure. Exploratory factor analysis revealed a three-factor structure of the QUAL-EC-J, with Cronbach's α values of 0.68-0.88. All subscales were negatively correlated with depression and anxiety. Each subscale was correlated with related measures: "symptom control" with "physical well-being"; "acceptance of disease and life" with "social and family well-being" and "meaning/peace"; and "preparation for end of life" with "emotional well-being" and "meaning/peace." CONCLUSIONS: The QUAL-EC-J has a three-factor structure with acceptable reliability and sufficient validity. Differences in the factor structure between the QUAL-EC-J and the QUAL-EC may be due to cultural factors. Study findings suggest that utilization of the QUAL-EC-J could help to improve research and clinical care in advanced cancer in Japan.