This paper reports on the valuation of quality-of-life states in the Alzheimer’s Disease Five Dimensions (AD-5D) instrument in a representative sample of the general population in Australia using the discrete-choice experiment with duration (DCETTO) elicitation technique.
A DCE with 200 choice sets of two quality-of-life (QoL) state–duration combinations blocked into 20 survey versions, with ten choice sets in each version, was designed and administered online to a sample representative of the Australian population. Two additional choice sets comprising internal consistency and dominance checks were included in each survey version. A range of model specifications investigating preferences with respect to duration and interactions between AD-5D dimension levels were estimated. Utility weights were developed, with estimated coefficients transformed to the 0 (being dead) to 1 (full health) scale, suitable for the calculation of quality-adjusted life-year (QALY) weights for use in economic evaluation.
In total, 1999 respondents completed the choice experiment. Overall, respondents were slightly better educated and had higher annual incomes than the Australian general population. The estimation results from different specifications and models were broadly consistent with the monotonic nature of the AD-5D: utility increased with increased life expectancy and decreased as the severity level for each dimension worsened. A utility value set was generated for the calculation of utilities for all QoL states defined by the AD-5D descriptive system.
The DCE-based utility value set is now available to use to generate QALYs for the economic evaluation of treatments and interventions targeting people with dementia and/or their family caregivers.
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The dataset used to generate the algorithm is available for reuse with commercial restriction in The University of Queensland eSpace repository .
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The authors would like to acknowledge the contributions of the AD5D project team, the project manager Alyssa Welch and participants of the online survey.
This study was supported by funding provided by the National Health and Medical Research Council (NHMRC) Partnership Centre on Dealing with Cognitive and Related Functional Decline in Older People (Grant no. GNT9100000). A/Prof Tracy Comans is supported by an NHMRC Boosting Dementia Research Fellowship. The contents of the published materials are solely the responsibility of the University of Queensland and the individual authors identified and do not reflect the views of the NHMRC or any other funding bodies or the funding partners.
Conflict of interest
Tracy Comans, Kim-Huong Nguyen, and Julie Ratcliffe have no conflicts of interest relevant to this manuscript. Brendan Mulhern and Donna Rowen were involved in the development of the DEMQOL-U, a utility instrument for dementia.
Ethical approval for this study was granted from Griffith University Human Research and Ethics Committee (approval number 2016/626) and University of Queensland Human Research and Ethics Committee (approval number 2017001481).
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Comans, T.A., Nguyen, KH., Ratcliffe, J. et al. Valuing the AD-5D Dementia Utility Instrument: An Estimation of a General Population Tariff. PharmacoEconomics 38, 871–881 (2020). https://doi.org/10.1007/s40273-020-00913-7