Quality-adjusted life year

Demonstration of quality-adjusted life years (QALYs) for two individuals. Individual A (who did not receive an intervention) has fewer QALYs than individual B (who received an intervention). The letters A and B designate the boundary lines, with the QALY for A being only the blue area, the QALY for B being the blue area plus the additional tan area. NB It is possible to experience an improvement in health-related quality of life with age, for example through healthier life choices.

The quality-adjusted life year or quality-adjusted life-year (QALY) is a generic measure of disease burden, including both the quality and the quantity of life lived.[1][2] It is used in economic evaluation to assess the value of medical interventions.[1] One QALY equates to one year in perfect health.[2] QALY scores range from 1 (perfect health) to 0 (dead).[3] QALYs can be used to inform health insurance coverage determinations, treatment decisions, to evaluate programs, and to set priorities for future programs.[3]

Critics argue that the QALY oversimplifies how actual patients would assess risks and outcomes, and that its use may restrict patients with disabilities from accessing treatment. Proponents of the measure acknowledge that the QALY has some shortcomings, but that its ability to quantify tradeoffs and opportunity costs from the patient and societal perspective make it a critical tool for equitably allocating resources.

Calculation

The QALY is a measure of the value of health outcomes to the people who experience them. It combines two different benefits of treatment—length of life and quality of life—into a single number that can be compared across different types of treatments.

Calculating a QALY requires two inputs. One is the utility value (or utility weight) associated with a given state of health by the years lived in that state. The underlying measure of utility is derived from clinical trials and studies that measure how people feel in these specific states of health. The way they feel in a state of perfect health equates to a value of 1 (or 100%). Death is assigned a utility of 0 (or 0%), and in some circumstances it is possible to accrue negative QALYs to reflect health states deemed "worse than dead."[3] The value people perceive in less than perfect states of health are expressed as a fraction between 0 and 1.

The second input is the amount of time people live in various states of health. This information usually comes from clinical trials.

To calculate the QALY, the two measures are multiplied. For example, one year lived in perfect health equates to 1 QALY. This can be interpreted as a person getting 100% of the value for that year. A year lived in a less than perfect state of health can also be expressed as the amount of value accrued to the person living it. For example, 1 year of life lived in a situation with utility 0.5 yields 0.5 QALYs—a person experiencing this state is getting only 50% of the possible value of that year. In other words, they value the experience of being in less than perfect health for a full year as much as they value living for half a year in perfect health (0.5 years × 1 Utility). This characteristic is what makes the QALY useful for evaluating tradeoffs.

Weighting

The utility values used in QALY calculations are generally determined by methods that measure people's willingness to trade time in different health states, such as those proposed in the Journal of Health Economics:[4]

  • Time-trade-off (TTO): Respondents are asked to choose between remaining in a state of ill health for a period of time, or being restored to perfect health but having a shorter life expectancy.
  • Standard gamble (SG): Respondents are asked to choose between remaining in a state of ill health for a period of time, or choosing a medical intervention which has a chance of either restoring them to perfect health or killing them.
  • Visual analogue scale (VAS): Respondents are asked to rate a state of ill health on a scale from 0 to 100, with 0 representing being dead and 100 representing perfect health. This method has the advantage of being the easiest to ask, but is the most subjective.

Another way of determining the weight associated with a particular health state is to use standard descriptive systems such as the EuroQol Group's EQ-5D questionnaire, which categorises health states according to five dimensions: mobility, self-care, usual activities (e.g. work, study, homework or leisure activities), pain/discomfort and anxiety/depression.[5]

Use

Data on medical costs are often combined with QALYs in cost-utility analysis to estimate the cost-per-QALY associated with a health care intervention. This parameter can be used to develop a cost-effectiveness analysis of any treatment. This incremental cost-effectiveness ratio (ICER) can then be used to allocate healthcare resources, often using a threshold approach.[6]

In the United Kingdom, the National Institute for Health and Care Excellence (NICE), which advises on the use of health technologies within the National Health Service, has since at least 2013 used "£ per QALY" to evaluate their utility.[1][7]

In the Netherlands the use of QALYs is also applied to decision making on security measures of highways and local roads and railway crossings.

History

QALY is credited to work by Klarman et al. (1968),[8] Fanshel and Bush (1970)[9] and Torrance et al. (1972)[10] who suggested the idea of length of life adjusted by indices of functionality or health.[11] A 1976 article by Zeckhauser and Shepard[12] was the first appearance in print of the term.[13] QALYs were later promoted through medical technology assessments conducted by the US Congress Office of Technology Assessment.

In 1980, Pliskin et al. justified the QALY indicator using multiattribute utility theory: if a set of conditions pertaining to agent preferences on life years and quality of life are verified, then it is possible to express the agent's preferences about couples (number of life years/health state), by an interval (Neumannian) utility function.[14] This utility function would be equal to the product of an interval utility function on "life years", and an interval utility function on "health state".

Debate

According to Pliskin et al., the QALY model requires utility independent, risk neutral, and constant proportional tradeoff behaviour.[14] Because of these theoretical assumptions, the meaning and usefulness of the QALY is debated.[15][16] Perfect health is difficult, if not impossible, to define. Some argue that there are health states worse than being dead, and that therefore there should be negative values possible on the health spectrum (indeed, some health economists have incorporated negative values into calculations). Determining the level of health depends on measures that some argue place disproportionate importance on physical pain or disability over mental health.[17]

The method of ranking interventions on grounds of their cost per QALY gained ratio (or ICER) is controversial because it implies a quasi-utilitarian calculus to determine who will or will not receive treatment.[18] However, its supporters argue that since health care resources are inevitably limited, this method enables them to be allocated in the way that is approximately optimal for society, including most patients. Another concern is that it does not take into account equity issues such as the overall distribution of health states—particularly since younger, healthier cohorts have many times more QALYs than older or sicker individuals. As a result, QALY analysis may undervalue treatments which benefit the elderly or others with a lower life expectancy. Also, many would argue that all else being equal, patients with more severe illness should be prioritised over patients with less severe illness if both would get the same absolute increase in utility.[19]

As early as 1989, Loomes and McKenzie recommended that research be conducted concerning the validity of QALYs.[20] In 2010, with funding from the European Commission, the European Consortium in Healthcare Outcomes and Cost-Benefit Research (ECHOUTCOME) began a major study on QALYs as used in health technology assessment.[21] Ariel Beresniak, the study's lead author, was quoted as saying that it was the "largest-ever study specifically dedicated to testing the assumptions of the QALY."[22] In January 2013, at its final conference, ECHOUTCOME released preliminary results of its study which surveyed 1361 people "from academia" in Belgium, France, Italy and the UK.[22][23][24] The researchers asked the subjects to respond to 14 questions concerning their preferences for various health states and durations of those states (e.g., 15 years limping versus 5 years in a wheelchair).[24] They concluded that:

  • "preferences expressed by the respondents were not consistent with the QALY theoretical assumptions";
  • quality of life can be measured in consistent intervals;
  • life-years and quality of life are independent of each other;
  • people are neutral about risk; and
  • willingness to gain or lose life-years is constant over time.[24]

ECHOUTCOME also released "European Guidelines for Cost-Effectiveness Assessments of Health Technologies," which recommended not using QALYs in healthcare decision making.[25] Instead, the guidelines recommended that cost-effectiveness analyses focus on "costs per relevant clinical outcome."[22][25]

In response to the ECHOUTCOME study, representatives of the National Institute for Health and Care Excellence, the Scottish Medicines Consortium, and the Organisation for Economic Co-operation and Development made the following points. First, QALYs are better than alternative measures.[22][23] Second, the study was "limited."[22][23] Third, problems with QALYs were already widely acknowledged.[23] Fourth, the researchers did not take budgetary constraints into consideration.[23] Fifth, the UK's National Institute for Health and Care Excellence uses QALYs that are based on 3395 interviews with residents of the UK, as opposed to residents of several European countries.[22] Finally, according to Franco Sassi, a senior health economist at the Organisation for Economic Co-operation and Development, people who call for the elimination of QALYs may have "vested interests".[22]

While supporters laud QALY’s efficiency, critics argue that use of QALY can cause medical inefficiencies because a less-effective, cheaper drug may be approved based on its QALY calculation.[26]

The use of QALYs has been criticized by disability advocates because otherwise healthy individuals cannot return to full health or achieve a high QALY score. Treatments for quadriplegics, patients with multiple sclerosis, or other disabilities are valued less under a QALY-based system.[27]

Critics also argue that a QALY-based system would limit research on treatments for rare disorders because the upfront costs of the treatments tend to be higher. Officials in the United Kingdom were forced to create the Cancer Drugs Fund to pay for new drugs regardless of their QALY rating because innovation had stalled since NICE was founded. At the time, one in seven drugs were turned down.[28]

The Partnership to Improve Patient Care, a group opposed to the adoption of QALY-based metrics, argued that a QALY-based system could exacerbate racial disparities in medicine because there is no consideration of genetic background, demographics, or comorbidities that may be elevated in minority racial groups that do not have as much weight in the consideration of the average year of perfect health.[29]

Critics have also noted that QALY only considers the quality of life when patients may choose to suffer negative side-effects to live long enough to attend a milestone event, such as a wedding or graduation.[26]

The Rule of rescue and immoral or "inhuman acting" are frequently used arguments to ignore cost-effectiveness analysis and the use of QALYs. Especially during the 2020/2021 Covid-19 pandemic, national responses represented a massive form of applying the ‘rule of rescue’ and ignoration of cost-effectiveness analysis (see e.g. Utilitarianism and the pandemic).

Both the Rule of rescue and immoral behaviour are heavily attacked by Shepley Orr and Jonathan Wolff in their 2014 article “Reconciling cost-effectiveness with the rule of rescue: the institutional division of moral labour” (https://link.springer.com/article/10.1007/s11238-014-9434-3). They argued that the “Rule of rescue” is the result of wrong reasoning. Cost-effectiveness reasoning with the aid of QALYs always leads to moral superior outcomes and optimal public health outcome, allthough not always perfect, given constraints of resources.

Future development

The UK Medical Research Council and others are exploring improvements to or replacements for QALYs.[30] Among other possibilities are extending the data used to calculate QALYs (e.g., by using different survey instruments); "using well-being to value outcomes" (e.g., by developing a "well-being-adjusted life-year"; and by value outcomes in monetary terms.[30] In 2018 HM Treasury set a discount rate of 1.5% for QALYs, which is lower than the discount rate for other costs and benefits, because the QALY is a direct utility measure.[31]

See also

Related units:

  • Disability-adjusted life year (DALY)
  • Wellbeing-adjusted Life Year WALY and Wellbeing Year (WELLBY)
  • Life-years lost
  • Value of a Statistical Life (VSL)

Other:

References

  1. 1 2 3 "Judging whether public health interventions offer value for money". National Institute for Health and Care Excellence. September 2013. Retrieved 2017-05-30.
  2. 1 2 "Glossary". National Institute for Health and Care Excellence. Retrieved 2017-05-30.
  3. 1 2 3 Weinstein, Milton C.; Torrance, George; McGuire, Alistair (2009). "QALYs: The Basics". Value in Health. 12: S5–S9. doi:10.1111/j.1524-4733.2009.00515.x. ISSN 1098-3015. PMID 19250132.
  4. ↑ Torrance, George E. (1986). "Measurement of health state utilities for economic appraisal: A review". Journal of Health Economics. 5 (1): 1–30. doi:10.1016/0167-6296(86)90020-2. PMID 10311607.
  5. ↑ EuroQol Group (1990-12-01). "EuroQol--a new facility for the measurement of health-related quality of life". Health Policy (Amsterdam, Netherlands). 16 (3): 199–208. doi:10.1016/0168-8510(90)90421-9. ISSN 0168-8510. PMID 10109801.
  6. ↑ Weinstein, Milton; Zeckhauser, Richard (1973-04-01). "Critical ratios and efficient allocation". Journal of Public Economics. 2 (2): 147–157. doi:10.1016/0047-2727(73)90002-9.
  7. ↑ "Guide to the methods of technology appraisal 2013". NICE. 2013. Archived from the original on 7 May 2015. Retrieved 15 Jun 2015.
  8. ↑ Klarman, Herbert E.; Francis, John O'S; Rosenthal, Gerald D. (1968). "Cost effectiveness analysis applied to the treatment of chronic renal disease". Medical Care. 6 (1): 48–54. doi:10.1097/00005650-196801000-00005. S2CID 72031480.
  9. ↑ Fanshel, Sol; Bush, J.W. (1970). "A health-status index and its application to health-services outcomes" (PDF). Operations Research. 18 (6): 1021–66. doi:10.1287/opre.18.6.1021. Retrieved 2014-05-06.
  10. ↑ Torrance, G W; Thomas, W.H.; Sackett, D.L. (1972). "A utility maximization model for evaluation of health care programs". Health Services Research. 7 (2): 118–133. ISSN 0017-9124. PMC 1067402. PMID 5044699.
  11. ↑ Kaplan, Robert M. (1995). "Utility assessment for estimating quality-adjusted life years" (PDF). Valuing health care: Costs, benefits, and effectiveness of pharmaceuticals and other medical technologies. pp. 31–60. Retrieved 2014-05-06.
  12. ↑ Zeckhauser, Richard; Shepard, Donald (1976). "Where Now for Saving Lives?". Law and Contemporary Problems. 40 (4): 5–45. doi:10.2307/1191310. ISSN 0023-9186. JSTOR 1191310.
  13. ↑ Sassi, Franco (2006). "Calculating QALYs, comparing QALY and DALY calculations". Health Policy and Planning. 21 (5): 402–408. doi:10.1093/heapol/czl018. ISSN 0268-1080. PMID 16877455.
  14. 1 2 Pliskin, J. S.; Shepard, D. S.; Weinstein, M. C. (1980). "Utility Functions for Life Years and Health Status". Operations Research. 28 (1): 206–24. doi:10.1287/opre.28.1.206. JSTOR 172147.
  15. ↑ Prieto, Luis; Sacristán, José A (2003). "Problems and solutions in calculating quality-adjusted life years (QALYs)". Health and Quality of Life Outcomes. 1: 80. doi:10.1186/1477-7525-1-80. PMC 317370. PMID 14687421. open access
  16. ↑ Mortimer, D.; Segal, L. (2007). "Comparing the Incomparable? A Systematic Review of Competing Techniques for Converting Descriptive Measures of Health Status into QALY-Weights". Medical Decision Making. 28 (1): 66–89. doi:10.1177/0272989X07309642. PMID 18263562. S2CID 40830765.
  17. ↑ Dolan, P (January 2008). "Developing methods that really do value the 'Q' in the QALY" (PDF). Health Economics, Policy and Law. 3 (1): 69–77. doi:10.1017/S1744133107004355. PMID 18634633. S2CID 25353890.
  18. ↑ Schlander, Michael (2010-05-23), Measures of efficiency in healthcare: QALMs about QALYs?, Institute for Innovation & Valuation in Health Care, archived from the original (PDF) on 2016-10-25, retrieved 2010-05-23
  19. ↑ Nord, Erik; Pinto, Jose Luis; Richardson, Jeff; Menzel, Paul; Ubel, Peter (1999). "Incorporating societal concerns for fairness in numerical valuations of health programmes". Health Economics. 8 (1): 25–39. doi:10.1002/(SICI)1099-1050(199902)8:1<25::AID-HEC398>3.0.CO;2-H. PMID 10082141. S2CID 16623609.
  20. ↑ Loomes, Graham; McKenzie, Lynda (1989). "The use of QALYs in health care decision making". Social Science & Medicine. 28 (4): 299–308. doi:10.1016/0277-9536(89)90030-0. ISSN 0277-9536. PMID 2649989.
  21. ↑ "ECHOUTCOME: European Consortium in Healthcare Outcomes and Cost-Benefit Research". Archived from the original on 2016-10-08.
  22. 1 2 3 4 5 6 7 Holmes, David (March 2013). "Report triggers quibbles over QALYs, a staple of health metrics". Nature Medicine. 19 (3): 248. doi:10.1038/nm0313-248. PMID 23467219.
  23. 1 2 3 4 5 Dreaper, Jane (24 January 2013). "Researchers claim NHS drug decisions 'are flawed'". BBC News. Retrieved 2017-05-30.
  24. 1 2 3 Beresniak, Ariel; Medina-Lara, Antonieta; Auray, Jean Paul; De Wever, Alain; Praet, Jean-Claude; Tarricone, Rosanna; Torbica, Aleksandra; Dupont, Danielle; Lamure, Michel; Duru, Gerard (2015). "Validation of the Underlying Assumptions of the Quality-Adjusted Life-Years Outcome: Results from the ECHOUTCOME European Project". PharmacoEconomics. 33 (1): 61–69. doi:10.1007/s40273-014-0216-0. ISSN 1170-7690. PMID 25230587. S2CID 5392762.
  25. 1 2 European Consortium in Healthcare Outcomes and Cost-Benefit Research (ECHOUTCOME). "European Guidelines for Cost-Effectiveness Assessments of Health Technologies" (PDF). Archived from the original (PDF) on 2015-08-14.
  26. 1 2 Krell, J; Kirkdale, R; O'Hanlon Brown, C; Tuthill, M; Waxman, J (2010). "The cost of a QALY". QJM : Monthly Journal of the Association of Physicians. 103 (9): 715–720. doi:10.1093/qjmed/hcq081. PMID 20519275. Retrieved 13 May 2021.
  27. ↑ Smith, William (24 January 2019). "Key Questions for Legislators on the Institute for Clinical and Economic Review (ICER)". Pioneer Institute. Retrieved 13 May 2021.
  28. ↑ Smith, William (22 February 2019). "The U.S. shouldn't use the 'QALY' in drug cost-effectiveness reviews". Stat News. Retrieved 13 May 2021.
  29. ↑ Roland, Denise (4 November 2019). "Obscure Model Puts a Price on Good Health—and Drives Down Drug Costs". Wall Street Journal. Retrieved 13 May 2021.
  30. 1 2 Brazier, John; Tsuchiya, Aki (2015). "Improving Cross-Sector Comparisons: Going Beyond the Health-Related QALY". Applied Health Economics and Health Policy. 13 (6): 557–565. doi:10.1007/s40258-015-0194-1. ISSN 1175-5652. PMC 4661222. PMID 26324402.
  31. ↑ "HMT Green Book". p. 28.
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