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

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.

A test of the predictive validity of non-linear QALY models using time trade-off utilities

This paper presents a test of the predictive validity of various classes of QALY models (i.e., linear, power and exponential models). We first estimated TTO utilities for 43 EQ-5D chronic health states and next these states were embedded in health profiles. The chronic TTO utilities were then used to predict the responses to TTO questions with health profiles. We find that the power QALY model clearly outperforms linear and exponential QALY models. Optimal power coefficient is 0.65. Our results suggest that TTO-based QALY calculations may be biased. This bias can be avoided using a power QALY model.Cost-utility analysis, QALYs, power QALY model, predictive validity, time tradeoff, Leex

Exponential Health Utility: A Characterization and Comments on a Paper by Happich and Mühlbacher.

In a recent paper Happich and Mühlbacher [Eur J Health Econom (2003) 4:292-294] proposed an axiom of constant absolute trade-off in life years, and studied the family of QALY models satisfying this axiom under expected utility and mutual utility independence between life years and health state. In this paper, we provide a complete characterization of the above-mentioned family of QALY models. This family should not be mistaken for the family of multiplicative expo-nential QALY models; in particular, it violates the zero-condition.

A new axiomatic approach to the evaluation of population health

We explore in this paper the implications of ethical and operational principles for the evaluation of population health. We formalize those principles as axioms for social preferences over distributions of health for a given population. We single out several focal population health evaluation functions, which represent social preferences, as a result of combinations of those axioms. Our results provide rationale for popular theories in health economics (such as the unweighted aggregation of QALYs or HYEs, and generalizations of the two, aimed to capture concerns for distributive justice) without resorting to controversial assumptions over individual preferences.population health, QALYs, HYEs, axioms

Men?s preferences for treatment of early stage prostate cancer: Results from a discrete choice experiment, CHERE Working Paper 2006/14

Prostate cancer is the most common cancer in men in Australia; each year over 10,000 Australians are diagnosed with this disease. There are a number of treatment options for early stage prostate cancer (ESPC); radical prostatectomy, external beam radiotherapy, brachytherapy, hormonal therapy and combined therapy. Treatment can cause serious side-effects, including severe sexual and urinary dysfunction, bowel symptoms and fatigue. Furthermore, there is no evidence as yet to demonstrate that any of these treatments confers a survival gain over active surveillance (watchful waiting). While patient preferences should be important determinants in the type of treatment offered, little is known about patients? views of the relative tolerability of side effects and of the survival gains needed to justify these. To investigate this, a discrete choice experiment (DCE) was conducted in a sample of 357 men who had been treated for ESPC and 65 age-matched controls. The sample was stratified by treatment, with approximately equal numbers in each treatment group. The DCE included nine attributes: seven side-effects and two survival attributes (duration and uncertainty). An orthogonal fractional set of 108 scenarios from the full factorial was used to generate three versions of the questionnaire, with 18 scenarios per respondent. Multinomial logit (MNL) and mixed logit (MXL) models were estimated. A random intercept MXL model provided a significantly better fit to the data than the simple MNL model, and adding random coefficients for all attributes dramatically improved model fit. Each side-effect had a statistically significant mean effect on choice, as did survival duration. Most attributes had significant variance parameters, suggesting considerable heterogeneity among respondents in their preferences. To model this heterogeneity, we included men?s health-related quality of life scores following treatment as covariates to see whether their preferences were influenced by their previous treatment experience. This study demonstrate how DCEs can be used to quantify the trade-offs patients make between side-effects and survival gains. The results provide useful insights for clinicians who manage patients with ESPC, highlighting the importance of patient preferences in treatment decisions.Prostate cancer, discrete choice experiment, preferences, quality of life

Seeing and doing: Feasibility study towards valuing visual impairment using simulation spectacles

Elicitation of utilities from those who do not have the health condition of interest generally uses verbal description of health states. This paper reports on the results of a small-scale investigation on the feasibility of an alternative approach, where health states are simulated and thus directly experienced by respondents. Three visual impairment health states were simulated using plastic spectacles, and were evaluated using the time trade-off. The first group of respondents (n = 19) found it difficult to assess visually impaired health states without referring to their own current health. With a further group of respondents (n = 14), we investigated the use of the respondents’ current health as the upper anchor of the time trade-off. Regression analysis shows that whilst there is a positive effect (p = 0.05) of the respondent’s own health state on the values from the first group, there is a non-significant negative effect (p = 0.36) on the values from the latter group with this revised method. Thus, it is feasible to simulate visual impairment in valuation exercises, but care must be taken to ensure what health state is effectively being valued

Individual Welfare and Subjective Well-Being : Commentary Inspired by Sacks, Stevenson and Wolfers

Sacks, Stevenson and Wolfers (2010) question earlier results like Easterlin's showing that long-run economic growth often fails to improve individuals'average reports of their own subjective well-being (SWB). We use World Values Survey data to establish that the proportion of individuals reporting happiness level h, and whose income falls below any xed threshold, always diminishes as h increases. The implied positive association between income and reported happiness suggests that it is possible in principle to construct multi-dimensional summary statistics based on reported SWB that could be used to evaluate economic policy

Impact of Complementarity and Heterogeneity on Health Related Utility of Life

This study aims at identifying determinants of health related quality of life in Poland, and in particular at verifying whether health domains are complements or substitutes and what the impact of heterogeneity of population on the health state valuation is. The paper uses data in panel structure coming from a survey conducted in Poland and consisting of 6700 valuations (after data cleaning) of EQ-5D health states with time trade-off method. Several econometric models are built in order to detect the impact of complementarity and heterogeneity. Random effects models as well as random parameters models estimated using Bayesian approach are used. The results show that health domains are complementary goods. Especially the lack of pain/discomfort is a complement to other health domains. Demographic factors influence how health state change impacts utility. These factors encompass sex, education, respondent's health state and even belief in life after death.health related quality of life, QALY, EQ-5D, complementarity, heterogeneity

A consistency test of the time trade-off

This paper tests the internal consistency of time trade-off utilities. We find significant violations of consistency in the direction predicted by loss aversion. The violations disappear for higher gauge durations. We show that loss aversion can also explain that for short gauge durations time trade-off utilities exceed standard gamble utilities. Our results suggest that time trade-off measurements that use relatively short gauge durations, like the widely used EuroQol algorithm (Dolan 1997), are affected by loss aversion and lead to utilities that are too high.Cost-Utility Analysis, Time Trade-Off, Loss Aversion