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Soc Sci Med. 2019 Nov;240:112560. doi: 10.1016/j.socscimed.2019.112560. Epub 2019 Sep 19.

Accounts from developers of generic health state utility instruments explain why they produce different QALYs: A qualitative study.

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Sydney School of Public Health, Edward Ford Building A27, The University of Sydney, NSW 2006, Australia.
Department of Health Services Research and Policy, Research School of Population Health, The Australian National University, 63 Eggleston Road, Acton, ACT 2601, Australia. Electronic address:
Centre for Evaluation and Research, Department of Health and Human Services, 50 Lonsdale Street, Melbourne, VIC 3000, Australia.
City University, London and Office of Health Economics, London, UK.
Yunus Centre for Social Business and Health, Glasgow Caledonian University, Cowcaddens Road, Glasgow, G40BA, UK.
Australian Centre for Health Engagement, Evidence and Values (ACHEEV), School of Health and Society, Faculty of Social Sciences, Building 15 Room 240, University of Wollongong, NSW 2522, Australia.



Despite the label "generic" health state utility instruments (HSUIs), empirical evidence shows that different HSUIs generate different estimates of Health-Related Quality of Life (HRQoL) in the same person. Once a HSUI is used to generate a QALY, the difference between HSUIs is often ignored, and decision-makers act as if 'a QALY is a QALY is a QALY'. Complementing evidence that different generic HSUIs produce different empirical values, this study addresses an important gap by exploring how HSUIs differ, and processes that produced this difference. 15 developers of six generic HSUIs used for estimating the QOL component of QALYs: Quality of Well-Being (QWB) scale; 15 Dimension instrument (15D); Health Utilities Index (HUI); EuroQol EQ-5D; Short Form-6 Dimension (SF-6D), and the Assessment of Quality of Life (AQoL) were interviewed in 2012-2013.


We identified key factors involved in shaping each instrument, and the rationale for similarities and differences across measures. While HSUIs have a common purpose, they are distinctly discrete constructs. Developers recalled complex developmental processes, grounded in unique histories, and these backgrounds help to explain different pathways taken at key decision points during the HSUI development. The basis for the HSUIs was commonly not equivalent conceptually: differently valued concepts and goals drove instrument design and development, according to each HSUI's defined purpose. Developers drew from different sources of knowledge to develop their measure depending on their conceptualisation of HRQoL.


We generated and analysed first-hand accounts of the development of the HSUIs to provide insight, beyond face value, about how and why such instruments differ. Findings enhance our understanding of why the six instruments developed the way they did, from the perspective of key developers of those instruments. Importantly, we provide additional, original explanation for why a QALY is not a QALY is not a QALY.


Australia; EQ-5D; Europe; Health Utilities Index (HUI); Health state utility instruments; North America; Preference weighted quality of life instruments; Short Form 6D (SF-6D)

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