Predictors of quality of life ratings from persons with dementia: the role of insight

Abstract

Evidence suggests that people with dementia are able to respond accurately and consistently to questions about quality of life (QoL), although large discrepancies exist between patient and proxy ratings. This may be due, in part, to the reduced insight of the person with dementia. The aim of this study was to explore the predictors of QoL ratings in a sample of people with mild dementia, with a particular focus on the role of insight. Sixty-nine participants and their caregivers were recruited from a memory clinic setting. The Bath Assessment of Subjective Quality of Life in Dementia (BASQID), Alzheimer's Disease-Related Quality of Life Scale, Memory Functioning Scale, Alzheimer's Disease Cooperative Study Activities of Daily Living (ADL) Inventory and Mini Mental State Examination were administered. Regression analyses indicated that the strongest predictor of QoL ratings from persons with dementia was their awareness of memory function, such that lower awareness was associated with higher QoL ratings. Proxy ratings of activity performance and enjoyment of activity were also significant predictors of BASQID scores. Awareness of memory function impacts directly on patient QoL ratings and can also mask the effects of changes in other outcomes such as ADL function. Measures of awareness should therefore be employed alongside patient QoL ratings in order to ensure they are interpreted accurately. Discrepancies between patient and proxy QoL ratings do not necessarily occur because of patient unreliability, but may instead reflect the application of distinct modes of QoL assessment that emphasise very different outcomes.