Convergent validity of EQ-5D with core outcomes in dementia: a systematic review

To explore through a systematic review, the convergent validity of EQ-5D (EQ-5D-3L and EQ-5D-5L (total score and dimensions)) with core outcomes in dementia and investigate how this may be impacted by rater-type; with the aim of informing researchers when choosing measures to use in dementia trials.

To identify articles relevant to the convergent validity of EQ-5D with core dementia outcomes, three databases were electronically searched to September 2022. Studies were considered eligible for inclusion within the review if they included individual level data from people with dementia of any type, collected self and/or proxy reported EQ-5D and collected at least one core dementia outcome measure. Relevant data such as study sample size, stage of dementia and administration of EQ-5D was extracted, and a narrative synthesis was adopted.

The search strategy retrieved 271 unique records, of which 30 met the inclusion criteria for the review. Twelve different core outcome measures were used to capture dementia outcomes: cognition, function, and behaviour/mood across the studies. Most studies used EQ-5D-3L (n = 27). Evidence related to the relationship between EQ-5D and measures of function and behaviour/mood was the most robust, with unanimous directions of associations, and more statistically significant findings. EQ-5D dimensions exhibited associations with corresponding clinical outcomes, whereby relationships were stronger with proxy-EQ-5D (than self-report).

Measuring health-rated quality of life in dementia populations is a complex issue, particularly when considering balancing the challenges associated with both self and proxy report. Published evidence indicates that EQ-5D shows evidence of convergent validity with the key dementia outcomes, therefore capturing these relevant dementia outcomes. The degree of associations with clinical measures was stronger when considering proxy-reported EQ-5D and differed by EQ-5D dimension type. This review has revealed that, despite the limited targeted psychometric evidence pool and reliance on clinical and observational studies, EQ-5D exhibits convergent validity with other dementia outcome measures.