| 1. |
- Tambour, Magnus, et al.
(författare)
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A Note on Confidence Intervals in Cost-Effectiveness Analysis
- 1998
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Ingår i: International journal of technology assessment in health care. - : Cambridge University Press. - 1471-6348 .- 0266-4623. ; 14:3, s. 467-471
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Tidskriftsartikel (refereegranskat)abstract
- How to obtain confidence intervals for cost-effectiveness ratios is complicated by the statistical problems of obtaining a confidence interval for a ratio of random variables. Different approaches have been suggested in the literature, but no consensus has been reached. We propose an alternative simple solution to this problem. By multiplying the effectiveness units by the price per effectiveness unit, both costs and benefits can be expressed in monetary terms and standard statistical techniques can be used to estimate a confidence interval for net benefits. This approach avoids the ratio estimation problem and explicitly recognizes that the price per effectiveness unit has to be known to provide cost-effectiveness analysis with a useful decision rule.
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| 2. |
- Zethraeus, Niklas, et al.
(författare)
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Value for money? A contingent valuation study of the optimal size of the Swedish health care budget
- 1995
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Ingår i: Health policy (Amsterdam). - : Elsevier Ireland Ltd. - 1872-6054 .- 0168-8510. ; 34:2, s. 135-143
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Tidskriftsartikel (refereegranskat)abstract
- The contingent valuation method has been developed in the environmental field to measure the willingness to pay for environmental changes using survey methods. In this exploratory study the contingent valuation method was used to analyse how much individuals are willing to spend in total in the form of taxes for health care in Sweden, i.e. to analyse the optimal size of the ‘health care budget’ in Sweden. A binary contingent valuation question was included in a telephone survey of a random sample of 1260 households in Sweden. With a conservative interpretation of the data the result shows that 50% of the respondents would accept an increased tax payment to health care of about SEK 60 per month ($1 = SEK 8). It is concluded that the results indicate that the population overall thinks that the current spending on health care in Sweden is on a reasonable level. There seems to be a willingness to increase the tax payments somewhat, but major increases does not seem acceptable to a majority of the population.
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| 3. |
- Bleichrodt, Han, et al.
(författare)
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An Experimental Test of a Theoretical Foundation for Rating-scale Valuations
- 1997
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Ingår i: Medical decision making. - : SAGE. - 1552-681X .- 0272-989X. ; 17:2, s. 208-216
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Tidskriftsartikel (refereegranskat)abstract
- A major advantage of using a rating scale in health-utility measurement is its practical applicability: the method is relatively easy to understand, and various health states can be assessed simultaneously. However, a theoretical foundation for rating-scale valuations has not been established. The primary aim of this paper is to present a theoretical foundation for rating-scale valuations based on the theory of measurable value functions and to provide a consistency test to see whether rating-scale valuations do indeed elicit a measurable value function. If rating-scale valuations elicit a measurable value function, then Dyer and Sarin have shown how they are related to von Neumann-Morgenstern (vNM) utilities. The appropriate technique to measure vNM utilities is the standard gamble. Torrance has suggested that rating-scale valuations and standard-gamble valuations are related by a power function. A secondary aim of this paper is to examine the relationship between rating-scale valuations and standard-gamble valuations hypothesized by Torrance. An experiment was designed to test consistency of rating-scale valuations and the relationship between rating-scale valuations and standard-gamble valuations. The experiment tested whether rating-scale valuations are independent of the context in which they are elicited, as they should be if they elicit points on a measurable value function. 80 Swedish and 92 Dutch respondents participated in the experiment. The results showed that rating-scale valuations depend on the number of preferred alternatives in the task and thus violate a basic property of measurable value functions. The estimation of the power function did not result in stable results: parameter estimates varied, in some cases there was indication of misspecification, and in most cases there was indication of heteroskedastic errors. The implications of these findings for the common use of rating-scale valuations in cost-utility analysis are serious: the dependency of the rating-scale valuations on the other health states included in the task casts serious doubts on the validity of the rating-scale method. Key words: QALYs; rating scale; cost-utility analysis; medical decision making. (Med Decis Making 1997;17:208-216))
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| 4. |
- Bleichrodt, Han, et al.
(författare)
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Characterizing QALYs by Risk Neutrality
- 1997
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Ingår i: Journal of Risk and Uncertainty. - : Springer. - 1573-0476 .- 0895-5646. ; 15:2, s. 107-114
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Tidskriftsartikel (refereegranskat)abstract
- This paper shows that QALYs can be derived from more elementary conditions than thought hitherto in the literature: it suffices to impose risk neutrality for life years in every health state. This derivation of QALYs is appealing because it does not require knowledge of concepts from utility theory such as utility independence. Therefore our axiomatization greatly facilitates the assessment of the normative (non)validity of QALYs in medical decision making. Moreover, risk neutrality can easily be tested in experimental designs, which makes it straightforward to assess the descriptive (non)validity of QALYs. Copyright 1997 by Kluwer Academic Publishers
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| 5. |
- Bleichrodt, Han, et al.
(författare)
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Probability Weighting and Utility Curvature in QALY-Based Decision Making
- 1999
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Ingår i: Journal of mathematical psychology. - : Elsevier Inc. - 1096-0880 .- 0022-2496. ; 43:2, s. 238-260
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Tidskriftsartikel (refereegranskat)abstract
- Quality-Adjusted Life-Years (QALYs) are currently the most important utility model in medical decision making. QALYs are calculated by adjusting years of life for the utility of the health state in which these years are spent. For normative reasons the standard gamble is the preferred method to measure health state utilities, but concern exists about its descriptive properties. Recent theoretical work has suggested that probability weighting can explain anomalies in standard gamble measurement. This paper shows that applying probability weighting in standard gamble measurement increases the consistency of QALYs with individual preferences. The consistency of QALYs with individual preferences is not significantly increased further if utility curvature is also taken into account.
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| 6. |
- Bleichrodt, Han, et al.
(författare)
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Standard gamble, time trade-off and rating scale: Experimental results on the ranking properties of QALYs
- 1997
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Ingår i: Journal of health economics. - : Elsevier B.V. - 1879-1646 .- 0167-6296. ; 16:2, s. 155-175
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Tidskriftsartikel (refereegranskat)abstract
- This paper compares the relative performance of quality adjusted life years (QALYs) based on quality weights elicited by rating scale (RS), time trade-off (TTO) and standard gamble (SG). The standard against which relative performance is assessed is individual preference elicited by direct ranking. The correlation between predicted and direct ranking is significantly higher for TTO-QALYs than for RS-QALYs and SG-QALYs. This holds both based on mean Spearman rank correlation coefficients calculated per individual and based on two social choice rules: the method of majority voting and the Borda rule. Undiscounted TTO-QALYs are more consistent with direct ranking than discounted TTO-QALYs.
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| 7. |
- Bleichrodt, Han, et al.
(författare)
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The Validity of QALYs : An Experimental Test of Constant Proportional Tradeoff and Utility Independence
- 1997
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Ingår i: Medical decision making. - 1552-681X .- 0272-989X. ; 17:1, s. 21-32
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Tidskriftsartikel (refereegranskat)abstract
- Pliskin, Shepard, and Weinstein identified three preference conditions that ensure that quality-adjusted life years (QALYs) represent preferences over gambles over chronic health profiles. This paper presents an experimental test of the descriptive validity of two of these preference assumptions: utility independence and constant proportional tradeoff. Eighty students at the Stockholm School of Economics and 92 students at Erasmus University Rotterdam participated in the experiment. The results of the ex periment support the descriptive validity of constant proportional tradeoff: both within groups and between groups constant proportional tradeoff could not be rejected. The results are less supportive of the descriptive validity of utility independence. Within- groups utility independence was rejected. Between-groups utility independence could not be rejected, but this may have been due to a lack of statistical power. Analysis of the individual responses revealed that without adjustment for imprecision of preference, 39 respondents (22.8%) satisfied constant proportional tradeoff. Twenty-three respon dents (13.4%) satisfied utility independence without adjustment for imprecision of pref erence. However, because of the relative unfamiliarity of the respondents with both the health states to be evaluated and the methods of health-state-utility measurement, it is likely that the respondents' preferences were imprecise. Adjusted for imprecision of preference, the upper estimates of the proportions of respondents who satisfied constant proportional tradeoff and utility independence, respectively, were 90.1% (155 respondents) and 75.6% (130 respondents). Pliskin et al. further derived that if an individual's preferences satisfy both constant proportional tradeoff and utility indepen dence, then these preferences can be represented by a more general, risk-adjusted QALY model. Without adjustment for imprecision of preference, ten respondents (5.8%) satisfied both constant proportional tradeoff and utility independence. Adjusted for imprecision of preference, the upper estimate of the proportion of respondents who satisfied both constant proportional tradeoff and utility independence was 68.6% (118 respondents). The results of this study indicate that constant proportional tradeoff holds approximately. The evidence is much weaker for utility independence, however. This has important implications for the use of QALY-type measures in medical decision making. Key words: QALYs; health utility measurements; medical decision making; individual preferences. (Med Decis Making 1996;17:21-32)
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| 8. |
- Blomquist, Glenn C., et al.
(författare)
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Experimental Results on Expressed Certainty and Hypothetical Bias in Contingent Valuation
- 1998
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Ingår i: Southern economic journal. - : Wiley-Blackwell. - 2325-8012 .- 0038-4038. ; 65:1, s. 169-177
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Tidskriftsartikel (refereegranskat)abstract
- Use of the contingent valuation method is controversial among economists because it is based on hypothetical rather than real choices. Previous experiments have suggested that the commonly used dichotomous choice contingent valuation method leads to hypothetical bias, i.e., overestimates the real willingness to pay. We carried out an experiment to compare the dichotomous choice contingent valuation method with real purchase decisions for a consumer good. We confirm previous findings that hypothetical yes responses overestimate real purchase decisions, but we cannot reject the null hypothesis that definitely sure yes responses correspond to real purchase decisions.
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| 9. |
- Blumenschein, Karen, et al.
(författare)
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An experimental test of question framing in health state utility assessment
- 1998
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Ingår i: Health policy (Amsterdam). - : Elsevier Ireland Ltd. - 1872-6054 .- 0168-8510. ; 45:3, s. 187-193
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Tidskriftsartikel (refereegranskat)abstract
- In the standard gamble and time trade-off methods of health state utility assessment, a specified health state and an alternative are compared. This alternative can be framed in terms of a loss or a gain in reference to the first health state. In this paper, we test whether this framing affects the estimated health state utilities. The experiment was carried out on a group of pharmacy students, randomly divided between the loss or gain version ( n=182). The null hypothesis of no difference between the loss and gain versions is rejected for the standard gamble method, but not for the time trade-off method.
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| 10. |
- Blumenschein, Karen, et al.
(författare)
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Economic Evaluation in Healthcare: A Brief History and Future Directions
- 1996
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Ingår i: PharmacoEconomics. - : Springer Nature. - 1179-2027 .- 1170-7690. ; 10:2, s. 114-122
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Tidskriftsartikel (refereegranskat)abstract
- Over the last decade there-has been tremendous interest in economic evaluations of healthcare programmes, especially in the pharmaceutical field. Economic evaluations started about 30 years ago as rather crude analyses, in which the-value of improved health was measured in terms of increased labour production. Now, more refined methods are available to measure health changes in terms of quality-adjusted life-years gained or willingness to pay. It is important to continue this development, and major fields for future work include the incorporation of quality-of-life measurements into economic evaluations and the linking of cost-effectiveness and cost-benefit analyses into a unified framework of economic evaluation. How to incorporate distributional issues is another important area. Finally, it seems crucial to further explore the link between economic evaluation and decision making, since the purpose of economic evaluations is to affect decision making.
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