Measuring Health-Related Quality of Life in Dementia

AbstractDementia presents unique challenges for the measurement of health-related quality of life (HRQL). The subjective nature of the HRQL construct, the cognitive demands of questionnaires, and the necessity of sometimes relying on a proxy report taken together mean that traditional questionnaires scored using classical psychometrics may not provide robust measurement. Advanced psychometric methods, such as those based on Rasch measurement theory, can provide possible solutions to these challenges. Rasch based methods have been used with the DEMQOL/DEMQOL-Proxy disease specific HRQL instrument to measure HRQL in people with dementia, to provide robust scales, to equate self- and proxy-reported instruments, and to create a cross walk from a proxy-reported measurement to the equivalent self-reported measurement. These methods also provide a qualitative understanding of statistical change. Advanced psychometric methods such as those based on Rasch measurement theory therefore provide a potentially powerful way to address the challenges of measuring HRQL for people with dementia. However, the use of these methods is not a quick fix. They require careful development of a conceptual framework describing the construct (HRQL) and a commitment to keeping the person with dementia’s perspective central at all stages of the process.