Measure of quality of life for Taiwanese persons with early to moderate dementia and related factors.

BACKGROUND This study validates the Chinese Dementia-Quality of Life instrument (DQoL) in patients with early to moderate stages of Alzheimer's disease (AD) (Clinical Dementia Rating Scale, CDR=0.5, 1, and 2; MMSE >or= 12). METHODS A cross-sectional design was used involving 98 participants (27 controls, 35 patients with questionable dementia (QD), and 36 patients with mild to moderate AD) and 51 paired family caregivers (FCs) (20 FCs of QD patients, 31 FCs of AD patients). FCs were recruited to evaluate patients' DQoL using the parallel form. Internal consistency, construct validity and concurrent validity of the DQoL were examined. RESULTS The findings indicated that the Chinese DQoL instrument has stable internal consistency but only moderate validity when used in early to moderate AD participants with MMSE greater than, or equal to 12. The DQoL and Self-esteem subscales were significantly different across the three dementia severity groups. The values of internal consistency of the DQoL and its five subscales were high for the ratings of both the patients and the FCs. The interscale correlations for the DQoL were almost all significant for patients' and FCs' ratings. Agreement of the DQoL and its subscales for patients and FCs was significant. However, two inconsistencies were found in the results of the factor analysis and the prior conceptualization of patients' DQoL, the subscales of Self-esteem and Negative Affect. Global cognitive impairment and self-care problems significantly correlated with the patients' DQoL, while the patients' depressive symptoms and self-care problems significantly correlated with the FCs' DQoL. CONCLUSIONS The Chinese DQoL reported by early to moderate AD patients has good reliability, but moderate validity because the patients' depressive symptoms did not correlate with their DQoL and the major subscales. Both patients' and FCs' ratings on DQoL are important in research and treatment decision making.