EQ-5D as a quality of life measure in people with dementia and their carers: evidence and key issues

Objectives: This article analyzes published studies on the application of the EQ-5D for the assessment of quality of life in patients with dementia and their carers. The EQ-5D, a generic instrument for measuring health-related quality of life, is widely used for economic evaluation in many areas of health research. However, there is considerable debate about the appropriateness of the EQ-5D for people with impaired cognition.

Methods: We conducted a systematic review of research studies published in the past 10 years that either used the EQ-5D as an outcome measure or investigated different aspects of the performance of the EQ-5D in studies of dementia.

Results: This study demonstrates that despite good feasibility and reliability of the EQ-5D instrument, there are problems with the validity of self-rated data because of a lack of association between patient and proxy ratings. There is a substantial ceiling effect for patient ratings. The visual analogue scale has poor reliability, even in patients with mild and moderate dementia. Different proxies (e.g., family carers, institutional carers, and health-care professionals) provide different ratings for patients' health.

Conclusion: Careful selection of assessment mode and appropriate proxies is important to ensure the EQ-5D validity in studies of patients with dementia. Because the cost of informal patient care represents a significant proportion of total costs of dementia treatment, the impact of dementia on carer's quality of life should be included in economic evaluation.