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-Morgensterm (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.
Comment In: Med Decis Making. 1998 Apr-Jun;18(2):2369566457
BACKGROUND: The entire risk factor profile should be taken into account when considering initiating cholesterol lowering drug treatment. Recent treatment guidelines are therefore based on the absolute risk of coronary heart disease. We estimated at what coronary risk it is cost-effective to initiate cholesterol lowering drug treatment in primary prevention for men and women of different ages in Sweden. METHODS: The cost-effectiveness was estimated as the incremental cost per quality-adjusted life-year (QALY) gained of cholesterol lowering drug treatment. Treatment was assumed to lower the risk of coronary heart disease by 31%. The analysis was carried out from a societal perspective including both direct and indirect costs of the intervention and morbidity, and the full future costs of decreased mortality. The coronary risk, in a Markov model of coronary heart disease, was raised until the cost per QALY gained corresponded to a specific threshold value per QALY gained. Three different threshold values were used: $40,000, $60,000 and $100,000 per QALY gained. RESULTS: The risk cut-off value for when treatment is cost-effective varied with age and gender. If society is willing to pay $60,000 to gain a QALY it was cost-effective to initiate treatment if the 5-year-risk of coronary heart disease exceeded 2.4% for 35-year-old men, 4.6% for 50-year-old men, and 10.4% for 70-year-old men. The corresponding risk cut-off values for women were 2.0%, 3.5% and 9.1%. CONCLUSIONS: The results can serve as a basis for treatment guidelines based on cost-effectiveness.
A social tariff of EuroQol time trade-off (TTO) values was recently presented. We compared the social tariff and patient TTO values among 104 women with mild and severe menopausal symptoms. The social tariff and patient TTO values were elicited both after and before hormone replacement therapy (HRT). There was a close correspondence between social-tariff values and patient TTO values for relatively good health states, whereas the social tariff TTO values were lower than the patient TTO values for severe health states.
This paper gives a detailed presentation of a computer model for evaluating the cost-effectiveness (CE) of hormone replacement therapy (HRT), describing the model's design, structure, and data requirements. The model needs data specified for costs, quality of life, risks, and mortality rates. As an illustration, the CE of HRT in Sweden is calculated. Two treatment strategies are evaluated for asymptomatic women: estrogen-only therapy and estrogen combined with a progestin. The model produces similar results compared with earlier studies. The CE ratios improve with the size of the risk reduction and generally with age. Further, estrogen-only therapy is associated with a lower cost per gained effectiveness unit compared with combined therapy. Uncertainty surrounding the long-term effects of HRT means that the CE estimates should be interpreted carefully. The model permits the inclusion of indirect costs and costs in added life-years, allowing the analysis to be made from a societal perspective, which is an improvement relative to previous studies.
It has been suggested that an open-ended follow-up question should be added to the binary contingent valuation question. Before this is generally recommended, it is important to evaluate the properties of such follow-up questions. Using a split sample approach, we test whether the open-ended follow-up is sensitive to the scope of the commodity being valued. No significant scope effects were detected. It is concluded that the results obtained do not support the use of an open-ended follow-up in contingent valuation applications.
Traditionally, economic evaluations in terms of cost-effectiveness analysis are based, explicitly or implicitly, on the assumption of constant returns to scale. This assumption has been criticized in the literature and the role of cost-effectiveness as a tool for decision making has been questioned. In this paper we analyze the case of increasing returns to scale due to fixed capital costs. Cost-effectiveness analysis is regarded as a tool for estimating a cost function. To this cost function two types of decision rules can be applied, the budget approach and the constant price approach. It is shown that in the presence of fixed capital costs the application of these two decision rules to a specific patient group will give different results. The budget approach may lead to suboptimizations, while using the price as a decision rule will give optimal solutions. With fixed capital costs and when an investment can be used for treating several patient groups, these groups are no longer independent. Therefore the cost-effectiveness analysis has to be performed simultaneously for all patient groups that are potential users of the investment.
There is a lack of methodological conformity in cost-effectiveness analyses of hypertension treatment. They differ with respect to assumptions about the effectiveness of treatment, the outcome measure chosen, the cost-concept, the discounting of effects and the duration of therapy. The aim of this paper is to review these issues and estimate the importance of different assumptions for the cost per life-year gained. To analyse these assumptions a computer simulation model was constructed based on the Framingham logistic risk equations and Swedish cost data. It is shown that the cost per life-year gained is highly sensitive towards many of these assumptions. It is also shown that the average cost-effectiveness ratios calculated in previous studies and the relevant marginal cost-effectiveness ratios can differ by several hundred per cent. The results of cost-effectiveness analyses in the hypertension field have to be interpreted with caution. Due to the lack of standardized methodology, the comparability between studies is limited. There is also a need to complement cost-effectiveness analysis in this area with other approaches, for example based on WTP.
OBJECTIVES. The aim of this study was to carry out a cost-effectiveness analysis of a multifactorial intervention programme in treated hypertensive patients. DESIGN. A cost-effectiveness analysis based on 3 years of follow-up in an open, randomized, parallel-group study with allocation either to a comprehensive, multiple-risk factor modification programme or to conventional treatment. SETTING. An outpatient clinic of a city hospital. SUBJECTS. Inclusion criteria were: male sex, age 50-72 (mean 66.4) years, treated hypertension and at least one of the following: serum cholesterol > or = 6.5 mmol L-1, and/or smoking and/or diabetes mellitus. A total of 508 patients were included in the study. INTERVENTIONS. Advice given to individuals, and group meetings based on nutritional advice and behavioural treatment principles. If necessary, drug therapy could be instituted to achieve the treatment goals in the intervention group: serum total cholesterol of
An analysis of the cost-effectiveness of simvastatin was conducted, based on the Scandinavian Simvastatin Survival Study (4S). The total cost of hospitalization in the placebo group was 52.8 million Swedish kronor (SEK) (5.15 million pounds), compared with SEK 36.0 million (3.51 million pounds) in the simvastatin group. This amounts to a 32% reduction, or a saving of SEK 16.8 million (1.6 million pounds) or SEK 7560 (738 pounds) per patient. The net cost per patient for the duration of the study (5.4 years) was SEK 13,540 (1324 pounds). Simvastatin treatment saved an estimated 0.377 undiscounted life years (0.240 life years discounted at 5% per annum). The cost of simvastatin therapy per discounted life-year saved was therefore SEK 56,400 (5502 pounds). Sensitivity analysis, examining the effect of different life expectancies, costs of initiation and monitoring of simvastatin therapy, and discount rates, showed the results to be stable. Conclusion. The cost per life-year saved of simvastatin in the treatment of post-myocardial infarction and angina patients, as determined from 4S data, is well within the range normally considered cost-effective.
Comment In: Eur Heart J. 1996 Jul;17(7):974-58809507