Aim: Measurement of health-related quality of life in people with dementia is a challenge, because of their special characteristics and the difficulties that this term entails itself. The present study aimed at assessing the psychometric properties of the EQ-5D rated by a familiar or a professional caregiver of institutionalized older adults with dementia.
Methods: We analyzed the EQ-5D psychometric properties from 525 questionnaires rated by proxy, in a sample of institutionalized older adults with dementia.
Results: The mean EQ-5D index score was 0.11 ± 0.38, and 51.54 ± 21.47 for the visual analog scale. The intraclass correlation coefficient was 0.72. Regarding internal consistency, Cronbach's alpha was 0.64, and the item-total correlation ranged from 0.33 to 0.53. Exploratory factor analysis identified a functional and a subjective factor, accounting for 67.35% of the variance. Convergent validity of EQ-5D with Quality of Life Alzheimer's Disease by proxy and Quality of Life in Late-stage Dementia scales was satisfactory (r = 0.36-0.58). The EQ-5D showed appropriate discriminative validity among patients grouped into several categories. Multiple linear regression models, using EQ-index and visual analog scale as dependent variables, identified dependence level, proxy characteristics, leisure and comorbidity as determinants of quality of life.
Conclusions: Despite some limitations in the more subjective dimensions, the proxy-rated EQ-5D showed satisfactory psychometric properties in the present study, suggesting that it is a valid and alternative instrument to assess quality of life in institutionalized older people with dementia.
Keywords: EQ-5D questionnaire; dementia; nursing homes; psychometric properties; quality of life.
© 2013 Japan Geriatrics Society.