Abstract
Background
Quality-adjusted life-years (QALYs) have been used since the 1980s as a standard health outcome measure for conducting cost-utility analyses, which are often inadequately labeled as ‘cost-effectiveness analyses’. This synthetic outcome, which combines the quantity of life lived with its quality expressed as a preference score, is currently recommended as reference case by some health technology assessment (HTA) agencies. While critics of the QALY approach have expressed concerns about equity and ethical issues, surprisingly, very few have tested the basic methodological assumptions supporting the QALY equation so as to establish its scientific validity.
Objectives
The main objective of the ECHOUTCOME European project was to test the validity of the underlying assumptions of the QALY outcome and its relevance in health decision making.
Methods
An experiment has been conducted with 1,361 subjects from Belgium, France, Italy, and the UK. The subjects were asked to express their preferences regarding various hypothetical health states derived from combining different health states with time durations in order to compare observed utility values of the couples (health state, time) and calculated utility values using the QALY formula.
Results
Observed and calculated utility values of the couples (health state, time) were significantly different, confirming that preferences expressed by the respondents were not consistent with the QALY theoretical assumptions.
Conclusions
This European study contributes to establishing that the QALY multiplicative model is an invalid measure. This explains why costs/QALY estimates may vary greatly, leading to inconsistent recommendations relevant to providing access to innovative medicines and health technologies. HTA agencies should consider other more robust methodological approaches to guide reimbursement decisions.
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Notes
If u(.) is a Neumanian-type utility function on E associated with an agent preferences, then, whatever the real numbers a and b such as a >0, function v(.) = au(.) + b is also a Neumanian-type utility function associated to the preferences of the same agent, and reciprocally. Then if u(.) is measured in a reference system S1, v(.) can be measure in a reference system S2 after a change of unit (role of coefficient a) and a change of origin (role of coefficient b).
In order to measure the utility of a health state z, so that z1 ≽z, where the utility of z1 is equal to 1, the duration t < T for which the pair (T,z) is indifferent to the pair (t, z 1) is assessed. It is then postulated that the utility of z, v(z), is equal to t/T. The assumption that enables this result, and which is not often stated, is that the utility function on the pairs (t,z) is of the type tv(z). It is precisely this specification that is at the origin of our interrogations.
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Acknowledgments
The authors gratefully acknowledge the suggestions of Louise Crathorne who kindly reviewed the manuscript.
Disclaimer
This project has received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under agreement n° 242203. The sole responsibility for the content of this article lies with the authors and does not necessarily reflect the opinion of the European Union. The European Commission is not responsible for any use that may be made of the information contained therein.
Conflicts of interests
No conflict of interests have been declared by the authors.
Authors’ contributions
AB, JPA, GD, and ML have designed the study. AB, AM-L, JPA, GD, and ML have carried out the methodological framework. ADW, J-CP, RT, AT, AM-L, and ML have organized the data collection. AB, DD, GD, and JPA have contributed to the writing of the manuscript. All authors have contributed to the interpretation of the results and to the revision of the manuscript. AB is acting as the overall guarantor.
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Beresniak, A., Medina-Lara, A., Auray, J.P. et al. Validation of the Underlying Assumptions of the Quality-Adjusted Life-Years Outcome: Results from the ECHOUTCOME European Project. PharmacoEconomics 33, 61–69 (2015). https://doi.org/10.1007/s40273-014-0216-0
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DOI: https://doi.org/10.1007/s40273-014-0216-0