Quality-corrected year of life

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A quality-adjusted life ( english quality-adjusted life year or QALY ) is a measure for the evaluation of a year of life in relation to health. A QALY of 1 means a year of full health, while a QALY of 0 means death . QALY is thus a useful value for a lifetime (year). The QALY is the most frequently used indicator in health economic evaluation.

The QALYs are a form of cost-benefit analysis . With this method, the advantages and disadvantages of a measure are measured in units of a cardinal utility function and are thus intended to map the multi-dimensional concept of health in an index. They are similar to the cost-benefit analysis , but differ from it in that the benefit is not measured in monetary units, but in quality of life (and duration). In addition to the QALYs, other benefit concepts were also developed in the cost-benefit analysis, e.g. B. DALY ( disability-adjusted life years ) or HYE ( healthy-years equivalent ).

development

The QALY concept was originally developed in 1968 by Herbert Klarman for the health economic analysis of chronic kidney failure. The current QALY concept was then further developed by Weinstein and Stason in 1977. Fanshel and Bush (1970) as well as Zeckhauser and Shepard (1976) also played a key role in the formulation. In 2002 Paul Dolan won the Philip Leverhulme Prize for his contributions to health economics, in particular for his work on the QALY concept.

Goal of the QALYs

The aim of this key figure in health services research is to convert the subjective good of health into a measurable figure in order to be able to carry out cost-benefit analyzes. In contrast to simpler cost-cost or cost-effectiveness analyzes, the QALY brings together different dimensions of medical outputs and, in contrast to the simpler concepts, also allows treatments to be compared across different diagnoses (interindication comparison). This theoretically makes it possible to make a transparent rationing decision: A medical measure is paid for as long as it does not exceed a limit of x EUR / QALY. Such a threshold value has not yet been explicitly specified anywhere; rather, intervals are used. An estimate assumes that the threshold of the English NICE ( National Institute for Health and Care Excellence ) from 20,000 GBP is 30,000 GBP. However, measures are also repeatedly approved whose costs per QALY are significantly higher than this value.

Conceptualization

At the core of the QALY model, the aspects of quantity of life (see life expectancy ) and quality of life are multiplicatively linked in order to calculate a QALY value:

.

Here T stands for the number of years and Q for the health-related quality of life (initially normalized from 0 to 1). It is believed that chemotherapy can extend a patient's life by an average of two months (approximately 0.17 years of age). However, the infusions are associated with side effects and are extremely stressful for the patient. The patient therefore rates his health-related quality of life during therapy as 0.8. Then this corresponds to a QALY value of .

A controversial question is whether QALYs need to be discounted . Discounting means that the further into the future, the less the benefit of a treatment is included in the calculation. Most proponents suggest a low single digit interest rate in the range of 3-5%.

Determination of the key figure

To calculate the QALY, two components are required, both of which are linked multiplicatively: on the one hand, the gain in lifetime (e.g. in years) and the health-related quality of life.

Lifetime

With targeted studies, it can usually be reliably measured whether and to what extent a measure can extend the lifespan.

life quality

Various instruments have been developed to record health-related quality of life.

  • Time trade-off
A possible derivation of the QALY is possible through the so-called time trade-off: "How many years of my life am I willing to give up if I can always live without any health restrictions." The remaining years correspond to the personal QALY. The respondent is given the choice between a condition with reduced quality of life - no specific diagnosis - for the rest of his statistical life expectancy and a period x in perfect health and subsequent death. The time span x is varied until the respondent is indifferent between the two states.
  • Standard lottery
The standard lottery (standard gamble) tries to find out what probability of death one would accept for a complete cure. Even more precise in the sense of expected utility theory is the question at which probability of death p one is indifferent between a condition with limited quality of life over a period of time t and a lottery with perfect health over the period of time t and the probability of death p.
  • Rating scales
A rating scale consists of a line with well-defined endpoints that describe worst health (usually death) and best health. Ask the interviewee to rate a particular state of health by indicating a point on the line that corresponds to that state of health. The EQ-5D, for example, is a health questionnaire that expresses a patient's quality of life in a one-dimensional number from 1 (very good) to 0 (extremely low). It is currently available in around 70 languages ​​and is the world's most frequently used questionnaire to measure health-related quality of life.

The QALY is an extra-welfarist concept; only a maximization within the health system is sought. It is not questioned whether similar effects can also be achieved by other measures at lower costs. For such a cost-benefit analysis, concepts have been developed that assess the health benefits in monetary terms. However, the determination of these values ​​is even more problematic than the determination of the QALYs, so that these concepts have not yet established themselves.

Criticism of the QALY concept

The QALY concept is an approach to the standardized evaluation of health services, in which the use of resources in the health sector is shown efficiently. However, although the problem of comparing different indications has been eliminated and the conflict of interest between profitability and financial feasibility has been resolved, the key figure is not undisputed. On the one hand, there are methodological arguments that cast doubt on the QALYs, and on the other, there are ethical opinions that criticize the concept.

One of the methodological counter-arguments is that, despite the uniform use of the time trade-off instrument, different studies produce extremely different results on the assessment of the quality of life effects in the test subjects. The scenarios presented, in which they should provide information about how much lifetime they would be willing to give up in return for a full quality of life, are not identical. This leads to only limited comparability. In addition, smaller changes in quality of life cannot yet be measurably proven. As a result, the QALY may not be calculated correctly and thus obscure the actual preferences of patients.

In addition, the increase in benefit of 0.1 QALYs in a seriously ill patient and an almost healthy person - who can already have a quality of life of 0.9 QALYs - are equated. According to the law of decreasing marginal utility , however, it can be assumed that a small improvement in the state of health is rated better the worse the general state was previously. This aspect is not taken into account in the QALY concept. Furthermore, from an ethical point of view, there is a charge of discrimination against sick or disabled people. Older people are also disadvantaged because life expectancy is included in the QALY calculation. Because of their advanced age, they can only gain fewer QALYs than younger people.

Web links

swell

  1. ^ Peter Zweifel, F. Breyer, M. Kifmann. Health economics. Berlin, Heidelberg, New York. 6th edition. 2013. p. 24.
  2. ^ Peter Zweifel, F. Breyer, M. Kifmann. Health economics. Berlin, Heidelberg, New York. 6th edition. 2013. p. 28.
  3. ↑ Klaus Koch, Andreas Gerber: QALYs in the cost-benefit assessment. Calculating in three dimensions . 2010. Extract from BARMER GEK Health Care Act 2010 (pages 32–48). Online version at archive.org (PDF) .
  4. ↑ Julia Schmidt-Wilke. Benefit measurement in health care: Analysis of the instruments against the background of goal function-dependent information use. Duv, 2004. p. 104.
  5. ↑ Schulenburg / Schöffski (ed.): Health economic evaluations. Springer, Berlin 2007, pp. 139 ff.
  6. ↑ Klaus Koch, Andreas Gerber: QALYs in the cost-benefit assessment. Calculating in three dimensions . 2010. Extract from BARMER GEK Health Care Act 2010 (pages 32–48). Online version saved on archive (pdf) .
  7. ^ Peter Zweifel, F. Breyer, M. Kifmann. Health economics. Berlin, Heidelberg, New York. 6th edition. 2013. p. 34.
  8. ↑ Schulenburg / Schöffski [eds.], Health Economic Evaluations, Springer, Berlin 2007, p. 361 ff.
  9. ^ Eva-Julia Weyler, Afschin Gandjour: Empirical Validation of Patient versus Population Preferences in Calculating QALYs . In: Health Services Research . tape 46 , no. 5 , April 21, 2011, ISSN  0017-9124 , p. 1562–1574 , doi : 10.1111 / j.1475-6773.2011.01268.x , PMID 21517837 , PMC 3207192 (free full text).
  10. ^ Peter Zweifel, F. Breyer, M. Kifmann. Health economics. Berlin, Heidelberg, New York. 6th edition. 2013. p. 40.
  11. ↑ C. Donaldson, R. Thomas, D. Torgerson (1997). Validity of open-ended and payment scale approaches to eliciting willingness to pay. Applied Economics 29: 79-84.

literature

  • Herbert E. Klarman, John O'S. Francis, Gerald D. Rosenthal: Cost effectiveness analysis applied to the treatment of chronic renal disease. In: Medical Care. Vol. 6, No. 1, 1968, pp. 48-54, JSTOR 3762651 .
  • Milton C. Weinstein, William B. Stason: Foundations of cost-effectiveness analysis for health and medical practices. In: The New England Journal of Medicine . Vol. 296, No. 13, 1977, pp. 716-721, doi: 10.1056 / NEJM197703312961304 .
  • Erik North. Cost-value analysis in health care. Making sense out of QALYs. Cambridge University Press, Cambridge et al. 1999, ISBN 0-521-64308-2 .
  • Matthias Graf von der Schulenburg, Wolfgang Greiner : Health economics. Mohr Siebeck, Tuebingen. 2000, ISBN 3-16-146681-0 .
  • Michael F. Drummond, Mark J. Sculpher, George W. Torrance, Bernie J. O'Brien, Greg L. Stoddart: Methods for the Economic Evaluation of Health Care Programs. 3rd edition. Oxford University Press, Oxford 2005, ISBN 0-19-852945-7 .