Reliability and validity of Quality of Life in Late-stage Dementia Scale of Chinese Version

Objective: To translate and test the reliability and validity of the Quality of Life in Late-stage Dementia Scale (QUALIDS), and to investigate its applicability in China. Methods: From December 2015 to January 2016, 205 patients with late-stage dementia who were in special care unit of old-age care institutions in Hunan province were selected by multistage cluster sampling method. The QUALIDS in English version was translated into Chinese, and then translated back to English again. Then it was sent to the original author for review, and finally the QUALIDS of Chinese version was formed after repeated contrast and comparison. The scale was filled in by the caregivers of the patients, and the scales were sent out and recovered on the spot. Two different caregivers filled in the QUALIDS of Chinese version repeatedly by targeting at 23 patients in two large old-age care institutions in Changsha city. The QUALIDS of Chinese version was reevaluated after 2 weeks. The reliability of the scale was evaluated by internal consistency, inter-rater reliability, test-retest reliability, and split-half reliability; the validity of the scale was evaluated by content validity, association validity and structure validity. Results: The Cronbach's α coefficient of the QUALIDS of Chinese version was 0.738, and the correlation coefficients of each item and total score were 0.354-0.755. Two different caregivers targeting at the 23 patients fill in the QUALIDS of Chinese version again, the intraclass correlation coefficients (ICC) of each item were 0.783-0.964, and the total scores of ICC was 0.892. The QUALIDS of Chinese version was evaluated again for the 23 patients after two weeks. The correlation coefficients of test-retest of each item were 0.575-0.878, and the total score of test-retest correlation coefficient was 0.819. The split-half reliability was 0.874. According to the feedback of experts, the content validity index (CVI) was 0.910. The correlation coefficients between QUALIDS of Chinese version and GDS, severity scale of NPI-Q, pain degree subscale of NPI-Q and PSMS score were -0.270, 0598, 0.576, and 0.267 (P<0.01). Three common factors were obtained by factor analysis, common factor 1 had items 2, 3, and 4, the common factor 2 had items 6, 7, and 11, and the common factor 3 had items 1, 9, and 10. Conclusion: The QUALID of Chinese version of is a reliable and valid instrument to evaluate the quality of life of patients in late-stage dementia.