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Improving the measurement of QALYs in dementia: developing patient- and carer-reported health state classification systems using Rasch analysis


  • Mulhern, B
  • Smith, SC
  • Rowen, D
  • Brazier, JE
  • Knapp, M
  • Lamping, DL
  • Loftus, V
  • Young, Tracey A.
  • Howard, RJ
  • Banerjee, S


Objectives: Cost-utility analysis is increasingly used to inform resource allocation. This requires a means of valuing health states before and after intervention. Although generic measures are typically used to generate values, these do not perform well with people with dementia. We report the development of a health state classification system amenable to valuation for use in studies of dementia, derived from the DEMQOL system, a measure of health-related quality of life in dementia by patient self-report (DEMQOL) and carer proxy-report (DEMQOL-Proxy). Methods: Factor analysis was used to determine the dimensional structure of DEMQOL and DEMQOL-Proxy. Rasch analysis was subsequently used to investigate item performance across factors in terms of item-level ordering, functioning across subgroups, model fit and severity-range coverage. This enabled the selection of one item from each factor for the classification system. A sample of people with a diagnosis of mild/moderate dementia (n=644) and a sample of carers of those with mild/moderate dementia (n=683) were used. Results: Factor analysis found different 5-factor solutions for DEMQOL and DEMQOL-Proxy. Following item reduction and selection using Rasch analysis, a 5-dimension classification for DEMQOL and a 4-dimension classification for DEMQOL-Proxy were developed. Each item contained 4 health state levels. Conclusion: Combining Rasch and classical psychometric analysis is a valid method of selecting items for dementia health state classifications from both the patient and carer perspectives. The next stage is to obtain preference weights so that the measure can be used in the economic evaluation of treatment, care and support arrangements for dementia.

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  • Mulhern, B & Smith, SC & Rowen, D & Brazier, JE & Knapp, M & Lamping, DL & Loftus, V & Young, Tracey A. & Howard, RJ & Banerjee, S, 2010. "Improving the measurement of QALYs in dementia: developing patient- and carer-reported health state classification systems using Rasch analysis," MPRA Paper 29948, University Library of Munich, Germany.
  • Handle: RePEc:pra:mprapa:29948

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    References listed on IDEAS

    1. Brazier, John & Ratcliffe, Julie & Salomon, Joshua & Tsuchiya, Aki, 2016. "Measuring and Valuing Health Benefits for Economic Evaluation," OUP Catalogue, Oxford University Press, edition 2, number 9780198725923.
    2. Mavranezouli, I & Brazier, JE & Young, Tracey A. & Barkham, M, 2009. "Using Rasch analysis to form plausible health states amenable to valuation: the development of CORE-6D from CORE-OM in order to elicit preferences for common mental health problems," MPRA Paper 29849, University Library of Munich, Germany.
    3. Drummond, Michael F. & Sculpher, Mark J. & Torrance, George W. & O'Brien, Bernie J. & Stoddart, Greg L., 2005. "Methods for the Economic Evaluation of Health Care Programmes," OUP Catalogue, Oxford University Press, edition 3, number 9780198529453.
    4. Brazier, John & Roberts, Jennifer & Deverill, Mark, 2002. "The estimation of a preference-based measure of health from the SF-36," Journal of Health Economics, Elsevier, vol. 21(2), pages 271-292, March.
    5. Richard Holland & Richard D Smith & Ian Harvey & Louise Swift & Elizabeth Lenaghan, 2004. "Assessing quality of life in the elderly: a direct comparison of the EQ-5D and AQoL," Health Economics, John Wiley & Sons, Ltd., vol. 13(8), pages 793-805.
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    Cited by:

    1. Mulhern, B & Rowen, D & Brazier, J & Jacoby, A & Marson, T & Snape, D & Hughes, D & Latimer, N & Baker, GA, 2010. "Developing a health state classification system from NEWQOL for epilepsy using classical psychometric techniques and Rasch analysis: a technical report," MPRA Paper 29970, University Library of Munich, Germany.
    2. Elizabeth Goodwin & Colin Green, 2016. "A Systematic Review of the Literature on the Development of Condition-Specific Preference-Based Measures of Health," Applied Health Economics and Health Policy, Springer, vol. 14(2), pages 161-183, April.

    More about this item


    quality adjusted life years; health related quality of life; Rasch analysis; preference-based measures of health; health states; dementia;

    JEL classification:

    • I31 - Health, Education, and Welfare - - Welfare, Well-Being, and Poverty - - - General Welfare, Well-Being
    • I19 - Health, Education, and Welfare - - Health - - - Other


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