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Utility functions for life years and health status: An additional remark


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  • Happich, Michael
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    Utility-based measures for health-related quality of life gain more and more importance in cost-effectiveness analysis. The axiomatic foundation qualifies them as decision weights in use of the QALY concept. But their use is strained for they are loaded with assumptions to make them work. Pliskin et al. (1980) have impressively shown which assumptions might be reasonable to combine quality of life with length of life, those attributes fundamental to the QALY concept. One of those assumptions is the so called „constant proportional tradeoff“. It states that people will always sacrifice the same proportion of remaining life years in order to gain better health. This assumption restricts the underlying utility functions for life years to those consistent with constant proportional risk posture, i.e. power, logarithmic and linear function. However, these types of function might be too restrictive for they do not reflect „constant absolut tradeoff“. That means people might rather exchange the same number of life years for better health, independent of remaining life expectancy. Pliskin et al. mentioned that case already and suggested the exponential function as a propper function to reflect the underlying constant absolut risk posture. I will deliver its proof. In addition, a survey among Tinnitus patients is mentioned that could further stress the validity of those functions. -- Nutzen-basierte Maße für gesundheitsbezogene Lebensqualität gewinnen für Kosten-Effektivitäts-Analysen immer mehr an Bedeutung. Ihre axiomatische Fundierung qualifiziert sie im Gebrauch des QALY Konzeptes. Aber die Nutzung ist problematisch, da sie von verschiedenen Annahmen abhängt. Pliskin et al. (1980) haben gezeigt, welche Annahmen plausibel sind, Lebensqualität mit Lebenslänge zu kombinieren, jenen Attributen, die grundlegend für das QALY Konzept sind. Eine ist die sogenannte „konstante proportionale Austausch“ Annahme. Sie besagt, dass Menschen immer eine proportionale Anzahl an Lebensjahre für bessere Gesundheit opfern würden. Diese Annahme beschränkt die zugrunde liegenden Nutzenfunktionen für Lebensjahre auf solche, die mit konstanter proportionaler Risikoeinstellung übereinstimmen, dass heisst Potenz- and Logarithmusfunktion oder eine lineare Funktion. Dennoch könnten diese Funktionstypen zu restriktiv sein, da sie nicht „konstanten absoluten Austausch“ darstellen können. Damit ist gemeint, dass Menschen eventuell immer dieselbe Anzahl von Lebensjahren aufgeben, unabhängig ihrer verbleibenden Lebenserwartung. Pliskin et al. erwähnten diesen Fall bereits und schlugen die Exponentialfunktion als geeigneten Funktionstyp vor, die zugrunde liegende konstante absolute Risikoeinstellung wiederzugeben. Ich werde den Beweis liefern. Eine Befragung unter Tinnitus Patienten könnte darüber hinaus die Gültigkeit dieser Funktionen unter Beweis stellen.

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    Paper provided by Technische Universität Berlin, School of Economics and Management in its series Discussion Papers with number 2001/6.

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    Date of creation: 2001
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    Handle: RePEc:zbw:tubsem:20016

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    Cited by:
    1. José Mª Abellán & José Luis Pinto & Ildefonso Méndez & Xabier Badía, 2004. "A test of the predictive validity of non-linear QALY models using time trade-off utilities," Economics Working Papers 741, Department of Economics and Business, Universitat Pompeu Fabra.


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