How does the EQ-5D perform when measuring quality of life in dementia against two other dementia-specific outcome measures?

This study aimed to assess and compare the psychometric performance of the EQ-5D in relation to other dementia-specific measures, the QoL-AD and DEMQoL, within a psychosocial intervention study. Two hundred and seventy-two people with dementia completed the EQ-5D, DEMQoL and QoL-AD. Convergent and discriminant validity of the measures were assessed, and inter-rater reliability was tested by comparing the self-reported and proxy scores of the measures. Internal consistency was tested using Cronbach's alpha. Results satisfy convergent validity amongst the three outcome measures. EQ-5D, DEMQoL and QoL-AD total scores were shown to be significantly correlated with each other (p < 0.001) in both participants with dementia and proxy reports. Results also satisfied discriminant validity for participant EQ-5D, DEMQoL and QoL-AD total scores. In relation to reliability between self and proxy scores, the EQ-5D showed higher reliability scores between participant and proxy total scores for mild and moderate level of cognitive impairment and performed better than the dementia-specific measures. Reliability assessed through Cronbach's alpha was satisfactory, indicating adequate internal consistency of all three measures. The results suggest that the EQ-5D might have advantages over other dementia-specific measures, and it could be used routinely and as a stand-alone measure of quality of life in dementia research.