Quality-of-life assessment in dementia: the use of DEMQOL and DEMQOL-Proxy total scores

Abstract

PurposeThere is a need to determine whether health-related quality-of-life (HRQL) assessments in dementia capture what is important, to form a coherent basis for guiding research and clinical and policy decisions. This study investigated structural validity of HRQL assessments made using the DEMQOL system, with particular interest in studying domains that might be central to HRQL, and the external validity of these HRQL measurements.MethodsHRQL of people with dementia was evaluated by 868 self-reports (DEMQOL) and 909 proxy reports (DEMQOL-Proxy) at a community memory service. Exploratory and confirmatory factor analyses (EFA and CFA) were conducted using bifactor models to investigate domains that might be central to general HRQL. Reliability of the general and specific factors measured by the bifactor models was examined using omega (ω) and omega hierarchical (ω h) coefficients. Multiple-indicators multiple-causes models were used to explore the external validity of these HRQL measurements in terms of their associations with other clinical assessments.ResultsBifactor models showed adequate goodness of fit, supporting HRQL in dementia as a general construct that underlies a diverse range of health indicators. At the same time, additional factors were necessary to explain residual covariation of items within specific health domains identified from the literature. Based on these models, DEMQOL and DEMQOL-Proxy overall total scores showed excellent reliability (ω h > 0.8). After accounting for common variance due to a general factor, subscale scores were less reliable (ω h < 0.7) for informing on individual differences in specific HRQL domains. Depression was more strongly associated with general HRQL based on DEMQOL than on DEMQOL-Proxy (−0.55 vs −0.22). Cognitive impairment had no reliable association with general HRQL based on DEMQOL or DEMQOL-Proxy.ConclusionsThe tenability of a bifactor model of HRQL in dementia suggests that it is possible to retain theoretical focus on the assessment of a general phenomenon, while exploring variation in specific HRQL domains for insights on what may lie at the ‘heart’ of HRQL for people with dementia. These data suggest that DEMQOL and DEMQOL-Proxy total scores are likely to be accurate measures of individual differences in HRQL, but that subscale scores should not be used. No specific domain was solely responsible for general HRQL at dementia diagnosis. Better HRQL was moderately associated with less depressive symptoms, but this was less apparent based on informant reports. HRQL was not associated with severity of cognitive impairment.Electronic supplementary materialThe online version of this article (doi:10.1007/s11136-016-1343-1) contains supplementary material, which is available to authorized users.

The Unforgettables: a chorus for people with dementia with their family members and friends

“…Participants with dementia and their caregivers completed demographic questions, the Communication subscale of the Family Assessment Measure (Skinner et al, 1983); and the Rosenberg Self-esteem Scale (Rosenberg, 1965). In addition, quality of life of the person with dementia was assessed with two scales, Quality of Life-AD (QOL-AD; 13 items: Logsdon et al, 2002) and the DemQoL (28 items; Chua et al, 2016). In addition to the domains assessed for both members of the dyad, caregivers also completed the MOS Social Support Survey (Sherbourne and Stewart, 1991), the SF-8 measure of Health Related Quality of Life (Ware et al, 2001), and the Geriatric Depression Scale (15-item version; Sheikh and Yesavage, 1986).…”

Why do staff and family think differently about quality of life in dementia? A qualitative study exploring perspectives in care homes

“…Maintaining quality of life in dementia is possible, desirable, and is the underpinning goal of care . As global dementia care strategies focus on living well with dementia, finding a way to meaningfully measure quality of life is an area of research …”

Item distribution, internal consistency, and structural validity of the German version of the DEMQOL and DEMQOL–proxy

“…No adequate results are available for psychometric testing of the German versions, which are required for both research and applied purposes [ 17 ]. To date, the DEMQOL has been subjected to at least four more latent variable modeling investigations in two countries since its foundation work [ 15 ], two factor analyses [ 4 , 18 ], bifactor modeling [ 19 ], and Rasch modeling [ 20 ].…”