Assessing the psychometric performance of EQ-5D-5L in dementia: a systematic review

Abstract

Background: EQ-5D is widely used for valuing changes in quality of life for economic evaluation of interventions for people with dementia. There are concerns about EQ-5D-3L in terms of content validity, poor inter-rater agreement and reliability in the presence of cognitive impairment, but there is also evidence to support its use with this population. An evidence gap remains regarding the psychometric properties of EQ-5D-5L. Objectives: To report psychometric evidence around EQ-5D-5L in people with dementia. Methods: A systematic review identified primary studies reporting psychometric properties of EQ-5D-5L in people with dementia. Searches were completed up to November 2020. Study selection, data extraction and quality assessment were undertaken independently by at least 2 researchers. Results: Evidence was extracted from 20 articles from 14 unique studies covering a range of dementia severity. Evidence of known group validity from 5 of 7 studies indicated that EQ-5D-5L distinguishes severity of disease measured by cognitive impairment, depression, level of dependence and pain. Convergent validity (9 studies) showed statistically significant correlations of weak and moderate strengths, between EQ-5D-5L scores and scores on other key measures. Statistically significant change was observed in only one of 6 papers that allowed this property to be examined. All seven studies showed a lack of inter-rater reliability between self and proxy reports with the former reporting higher EQ-5D-5L scores than those provided by proxies. Five of ten studies found EQ-5D-5L to be acceptable, assessed by whether the measure could be completed by the PwD and/or by the amount of missing data. As dementia severity increased, the feasibility of self-completing EQ-5D-5L decreased. Three papers reported on ceiling effects, two found some evidence in support of ceiling effects, and one did not. Conclusions: EQ-5D-5L seems to capture the health of people with dementia on the basis of known-group validity and convergent validity, but evidence is inconclusive regarding the responsiveness of EQ-5D-5L. As disease progresses, the ability to self-complete EQ-5D-5L is diminished.