Utility Elicitation Methods Research Articles

A Systematic Literature Review of Health Utility Values in Breast Cancer

BackgroundHealth utility values (HUVs) are important inputs to the cost-utility analysis of breast cancer interventions.PurposeProvide a catalog of breast cancer–related published HUVs across different stages of breast cancer and treatment interventions.Data SourcesSystematic searches of MEDLINE, MEDLINE In-Process, EMBASE, Web of Science, CINAHL, PsycINFO, EconLit, and Cochrane databases (2005–2017).Study SelectionStudies published in English that reported mean or median HUVs using direct or indirect methods of utility elicitation for breast cancer.Data ExtractionIndependent reviewers extracted data on a preestablished and piloted form; disagreements were resolved through discussion.Data AnalysisMixed-effects meta-regression using restricted maximum likelihood modeling was conducted for intervention type, stage of breast cancer, and typical clinical and treatment trajectory of breast cancer patients to assess the effect of study characteristics (i.e., sample size, utility elicitation method, and respondent type) on HUVs.Data SynthesisSeventy-nine studies were included in the review. Most articles (n = 52, 66%) derived HUVs using the EQ-5D. Patients with advanced-stage breast cancer (range, 0.08 to 0.82) reported lower HUVs as compared with patients with early-stage breast cancer (range, 0.58 to 0.99). The meta-regression analysis found that undergoing chemotherapy and surgery and radiation, being diagnosed with an advanced stage of breast cancer, and recurrent cancer were associated with lower HUVs. The members of the general public reported lower HUVs as compared with patients.LimitationsThere was considerable heterogeneity in the study population, health states assessed, and utility elicitation methods.ConclusionThis review provides a catalog of published HUVs related to breast cancer. The substantial heterogeneity in the health utility studies makes it challenging for researchers to choose which HUVs to use in cost-utility analyses for breast cancer interventions.

Preference for Alternate-Day Versus Conventional In-Center Dialysis: A Health Utility Elicitation.

Background:Mortality rates for patients on hemodialysis (HD) continue to be high, in particular, following the long interdialytic period, yet thrice-weekly conventional HD (CHD) is still an almost universal regimen. Alternate-day dialysis (ADD) may have advantages over the current schedule because it would eliminate the long interdialytic break. A preliminary, as yet unpublished, patient simulation and cost-utility analysis compared CHD versus ADD and demonstrated that the economic attractiveness of ADD was sensitive, in particular, to patients’ preference for ADD versus CHD. To date, this preference has not been elicited.Objective:To elicit utilities for both CHD and ADD using 3 standard elicitation methods among a prevalent cohort of patients on CHD.Design:This study is a single-center survey of patient preferences (utilities).Setting:This study took place within the dialysis units of Sunnybrook Health Centre, a university-affiliated teaching hospital in Toronto, Ontario, Canada, which encompasses 174 patients on in-center HD.Patients:Those older than 18 years of age, on thrice-weekly HD, were included in this study.Measurements:Descriptive statistics were used to summarize patient characteristics and the utility values generated. A multiple linear regression was performed to determine an association between participant characteristics and the utility ratio.Methods:Via standardized face-to-face interviews by a single investigator, 3 utility elicitation methods, visual analogue scale (VAS), time trade-off (TTO), and standard gamble (SG), were administered to generate utilities for each patient for their current health state of CHD (thrice-weekly). After completing this task, we provided each patient with a concise summary regarding the current literature on how ADD may impact their health. Finally, patients were asked to envision their health while on an ADD regimen while repeating the VAS, TTO, and SG.Results:We recruited 65 participants. The mean utilities of CHD versus ADD were similar for all 3 methods. Visual analogue scale, TTO, and SG had utility values of 0.6 ± 0.2, 0.6 ± 0.3, and 0.7 ± 0.3, and 0.6 ± 0.2, 0.7 ± 0.3, and 0.7 ± 0.3 for CHD and ADD, respectively. The ratio for CHD to ADD was 1.1 ± 0.4, 1.1 ± 0.5, and 1.0 ± 0.2 for VAS, TTO, and SG, respectively.Limitations:Small sample size from a single center, where not all participants agreed to participate, wide variability in participant responses and requiring patients to conceptually imagine life on ADD may have affected our results.Conclusions:Compared with CHD, there was no difference in the preference toward ADD which demonstrates promise that adopting an alternate-day schedule may be acceptable to patients. Furthermore, with the generation of a utility for ADD, this will allow for more precise estimates in future simulation studies of the economic attractiveness of ADD.Trial registration:Not required as this article is not a systematic review nor does it report the results of a health care intervention.

Preference-Based Health-Related Quality of Life Outcomes Associated with Preterm Birth: A Systematic Review and Meta-analysis.

Assessments of health-related quality of life outcomes associated with preterm birth provide valuable complementary data to the objective biomedical assessments that have traditionally been reported. The objective of this study was to perform a systematic review and meta-analysis of health utility values associated with preterm birth generated using preference-based approaches to health-related quality of life measurement. Systematic searches of MEDLINE, Web of Science, EconLit, EMBASE, CINAHL, PsycINFO, the Cochrane Library and SCOPUS were performed, covering the literature from inception of the search engines to 26June 2018. Studies reporting health utility values estimated using either direct or indirect utility elicitation methods and published in the English language were included. Central descriptive statistics and measures of variability surrounding health utility values for each study and control group, and differences between comparator groups, are reported for each included article. The effect of preterm birth on health utility values was estimated using a hierarchical linear model in a linear mixed-effects meta-regression. Of 2139 unique articles retrieved, 20 articles met the inclusion criteria. All but one study used the Health Utilities Index (HUI) Mark2 (HUI2) or Mark3 (HUI3) measures as their primary health utility assessment method. All studies reporting health utility values for individuals born preterm or at low birthweight and a control group of individuals born at full term or normal birthweight reported lower utility values in the study groups, regardless of age at assessment, respondent type or valuation method. The meta-regression revealed that preterm birth was associated with a mean utility decrement of 0.066 (95% confidence interval [CI] 0.035-0.098; p < 0.001) after controlling for valuation method, respondent type, administration mode, year of publication, geographical region of study, study setting and age at assessment. Evidence identified by this review can act as data inputs into future economic evaluations of preventive or treatment interventions for preterm birth. Future research should focus particularly on estimating health utility values during the various stages of adulthood, and incorporating the effects of preterm birth on the preference-based health-related quality of life outcomes of parents and other family members.

Systematic review and evidence synthesis of non-cervical human papillomavirus-related disease health system costs and quality of life estimates

BackgroundMany economic evaluations of human papillomavirus vaccination should ideally consider multiple disease outcomes, including anogenital warts, respiratory papillomatosis and non-cervical cancers (eg, anal, oropharyngeal, penile, vulvar and vaginal cancers). However,...

The Effect of Changing Utility Elicitation Methods in Cardiovascular Disease: A Systematic Literature Review

The Effect of Changing Utility Elicitation Methods in Cardiovascular Disease: A Systematic Literature Review

Health State Utility Values for Age-Related Macular Degeneration: Review and Advice

Health state utility values are a major source of uncertainty in economic evaluations of interventions for age-related macular degeneration (AMD). This review identifies and critiques published utility values and methods for eliciting de novo utility values in AMD. We describe how utility values have been used in healthcare decision making and provide guidance on the choice of utility values for future economic evaluations for AMD. Literature was searched using PubMed, and health technology assessments (HTA) were searched using HTA agency websites to identify articles reporting utility values or approaches to derive utility values in AMD and articles applying utilities for use in healthcare decision making relating to treatments for AMD. A total of 70 studies qualified for data extraction, 22 of which were classified as containing utility values and/or elicitation methods, and 48 were classified as using utility values in decision making. A large number of studies have elicited utility values for AMD, although those applied to decision making have focused on a few of these. There is an appreciation of the challenges in the measurement and valuation of health states, with recent studies addressing challenges such as the insensitivity of generic health-related quality of life (HRQoL) questionnaires and utility in the worse-seeing eye. We would encourage careful consideration when choosing utility values in decision making and an explicit critique of their applicability to the decision problem.

A structured review of health utility measures and elicitation in advanced/metastatic breast cancer.

BackgroundHealth utilities are increasingly incorporated in health economic evaluations. Different elicitation methods, direct and indirect, have been established in the past. This study examined the evidence on health utility elicitation previously reported in advanced/metastatic breast cancer and aimed to link these results to requirements of reimbursement bodies.MethodsSearches were conducted using a detailed search strategy across several electronic databases (MEDLINE, EMBASE, Cochrane Library, and EconLit databases), online sources (Cost-effectiveness Analysis Registry and the Health Economics Research Center), and web sites of health technology assessment (HTA) bodies. Publications were selected based on the search strategy and the overall study objectives.ResultsA total of 768 publications were identified in the searches, and 26 publications, comprising 18 journal articles and eight submissions to HTA bodies, were included in the evidence review. Most journal articles derived utilities from the European Quality of Life Five-Dimensions questionnaire (EQ-5D). Other utility measures, such as the direct methods standard gamble (SG), time trade-off (TTO), and visual analog scale (VAS), were less frequently used. Several studies described mapping algorithms to generate utilities from disease-specific health-related quality of life (HRQOL) instruments such as European Organization for Research and Treatment of Cancer Quality of Life Questionnaire – Core 30 (EORTC QLQ-C30), European Organization for Research and Treatment of Cancer Quality of Life Questionnaire – Breast Cancer 23 (EORTC QLQ-BR23), Functional Assessment of Cancer Therapy – General questionnaire (FACT-G), and Utility-Based Questionnaire-Cancer (UBQ-C); most used EQ-5D as the reference. Sociodemographic factors that affect health utilities, such as age, sex, income, and education, as well as disease progression, choice of utility elicitation method, and country settings, were identified within the journal articles. Most submissions to HTA bodies obtained utility values from the literature rather than exploring the HRQOL data obtained during clinical development. This was critiqued by the National Institute for Health and Clinical Excellence (NICE). Furthermore, the impact of age on utilities was highlighted by NICE and it was suggested that an age match of the study population should be attempted.ConclusionHealth utilities are recorded across the globe to varying extents and using differing elicitation methods. Manufacturers seeking reimbursement need to be aware of the country-specific requirements for elicitation of health utilities.

Decision Analysis Tool for Small Satellite Risk Management

Risk management plans improve the likelihood of mission success by identifying potential failures early and planning mitigation methods to circumvent any issues. However, in the aerospace industry to date, risk management plans have typically only been used for larger and more expensive satellites and have rarely been applied to lower-cost satellites such as CubeSats. Furthermore, existing risk management plans typically require experienced personnel and significant time to perform the analysis. The CubeSat Decision Advisor tool uses components of decision theory such as decision trees, multi-attribute utility theory, and utility elicitation methods to determine the expected utilities of proposed mitigation techniques to a mission risk. Based on the user’s value preference system, assessment of success probabilities, and resources required for a given mitigation technique, the tool suggests the course of action that will normatively yield the most value for the COST, people, and time resources required. This research creates a risk management software tool never before available that is easily accessible and usable for low-cost small satellite missions due to its construction in Microsoft™ Excel. A demonstration analysis is conducted on a university CubeSat mission as a case study. The target audience for this tool is primarily university labs, which could not otherwise afford expensive software packages. However, the tool is broadly applicable to all organizations, including government, academic, and corporate, and is not constrained to university small satellite mission architectures.

Brazilian Valuation of EQ-5D-3L Health States: Results from a Saturation Study.

Most EQ-5D-3L valuation studies include the same sample of health states that was used in the protocol of the original UK Measurement and Valuation of Health (MVH) study. Thus far, no studies using a time tradeoff utility elicitation method have been carried out using all 243 EQ-5D health states. Because the values and preferences regarding health outcomes differ among countries, it is essential to have country-specific data to enable local high-level decisions regarding resource allocation. This study developed a country-specific set of values for EQ-5D-3L health states. A multicentric study was conducted in 4 Brazilian areas. A probabilistic sample of the general population, aged 18 to 64 y, stratified by age and gender, was surveyed. The interview followed a revised version of the MVH protocol, in which all 243 health states were valued. Each respondent ranked and valued 7 health states using the TTO in a home interview. Data were collected from 9148 subjects. The best-fitting regression model was an individual-level mixed-effects model without any interaction terms. The dimensions "Mobility" and "Usual Activities" were associated with higher losses in health state utility value. The "Anxiety/Depression" dimension was the domain that contributed to lower losses in health state utility value. This study generated significant insight into the Brazilian population's health preferences that can be applied to health technology assessment and economic analyses in Brazil. This information represents an important new tool that can be used in Brazilian health policy creation and evaluation.

UceWeb: a web-based collaborative tool for collecting and sharing quality of life data.

This work aims at building a platform where quality-of-life data, namely utility coefficients, can be elicited not only for immediate use, but also systematically stored together with patient profiles to build a public repository to be further exploited in studies on specific target populations (e.g. cost/utility analyses). We capitalized on utility theory and previous experience to define a set of desirable features such a tool should show to facilitate sound elicitation of quality of life. A set of visualization tools and algorithms has been developed to this purpose. To make it easily accessible for potential users, the software has been designed as a web application. A pilot validation study has been performed on 20 atrial fibrillation patients. A collaborative platform, UceWeb, has been developed and tested. It implements the standard gamble, time trade-off and rating-scale utility elicitation methods. It allows doctors and patients to choose the mode of interaction to maximize patients’ comfort in answering difficult questions. Every utility elicitation may contribute to the growth of the repository. UceWeb can become a unique source of data allowing researchers both to perform more reliable comparisons among healthcare interventions and build statistical models to gain deeper insight into quality of life data.

Estimating utility functions using generalized maximum entropy

This paper estimates von Neumann and Morgenstern utility functions using the generalized maximum entropy (GME), applied to data obtained by utility elicitation methods. Given the statistical advantages of this approach, we provide a comparison of the performance of the GME estimator with ordinary least square (OLS) in a real data small sample setup. The results confirm the ones obtained for small samples through Monte Carlo simulations. The difference between the two estimators is small and it decreases as the width of the parameter support vector increases. Moreover, the GME estimator is more precise than the OLS one. Overall, the results suggest that GME is an interesting alternative to OLS in the estimation of utility functions when data are generated by utility elicitation methods.

The impact of CAP policy in farmer's behavior – A modeling approach using the Cumulative Prospect Theory

This paper proposes a modeling approach to evaluate the impact of economic policies on the decision maker's behavior. This modeling approach incorporates the agent's preferences, estimated through utility elicitation methods, into the objective function of a discrete sequential stochastic programming model that describes the uncertainties and the constraints faced by the decision maker. Our approach was applied to nine farmers of Portugal. The elicitation of the farmers’ preferences reveals that the Cumulative Prospect Theory is relevant to describe the farmers’ behavior under risk. Our programming model was used to evaluate the impact of the Common Agricultural Policy with partial and full decoupling of subsidies.

Designing utility-based recommender systems for e-commerce: Evaluation of preference-elicitation methods

Recommender systems are useful in reducing information overload and improving decision making. Utility-based recommender systems provide recommendations based on the computation of the utility of each item for the user. Some utility-elicitation methods have been developed on the basis of multi-attribute utility theory (MAUT) to represent a decision maker’s complete preference. This study investigates whether these utility-based techniques outperform the traditional content-based technique for online recommendations. A laboratory experiment was conducted in two e-commerce contexts to compare the decomposed and holistic utility-based methods, simple multi-attribute rating technique exploiting ranks (SMARTER) and radial basis function network (RBFN), with the content-based method vector space model (VSM) in terms of recommendation accuracy, time expense, and user perceptions. The results demonstrate that the performances of utility-based methods depend on recommendation contexts. Furthermore, this study proposes guidelines for choosing appropriate recommendation methods in different contexts.

The correction of TTO-scores for utility curvature using a risk-free utility elicitation method

This paper describes and employs a new method to correct time tradeoff (TTO)-scores for utility of life duration curvature. In contrast to most previous attempts to do so, it uses a risk-free method that corresponds well to the risk-free properties of the TTO-method. In addition, the method is robust to several biases that occur under methods that incorporate risk. Our results show a significant degree of curvature in utility of life duration and therefore a clear bias in TTO-scores. The risk-free method seems to be useful to correct TTO-scores for this influence and leads to significantly higher quality-adjustment factors.

Recombinant Erythropoietin for Chemotherapy-Related Anaemia

To assess both the health-related quality of life (HR-QOL) and the economic value of erythropoietin treatment in chemotherapy-related anaemia using direct utility elicitation and discrete choice experiment (DCE) methods from a societal perspective in the UK. The time trade-off (TTO) method was employed to obtain utility values suitable for the calculation of QALYs for no, mild, moderate and severe anaemia. Health-state descriptions were developed using the Functional Assessment of Cancer Therapy - Anaemia (FACT-AN) subscale and the EQ-5D questionnaires, and were validated by clinical experts and patients. In addition, a DCE was implemented to elicit preferences for various anaemia treatment scenarios. The DCE analysis comprised important aspects of treatment identified from a literature review and by consultation with expert clinicians and cancer patients. The DCE included cost as an attribute in order to elicit willingness-to-pay (WTP) values (pound, 2004 values). The two methods were applied in the same cross-sectional sample of 110 lay people. Face-to-face interviews were conducted between February and March 2004. The mean utility scores were 0.86 (standard error [SE] 0.014) for the no-anaemia state, and 0.78 (SE 0.016), 0.61 (SE 0.020) and 0.48 (SE 0.020) for the mild, moderate and severe anaemia states, respectively. The DCE results revealed the following preferences as significant predictors of choice: higher level of relief from fatigue, lower duration of administration, subcutaneous/intravenous administration versus cannula injection, GP versus hospital location, lower risk of infection or allergic reactions and lower cost per month to the patient. Attribute levels were valued higher for recombinant erythropoietin than for blood transfusion; this is reflected in an incremental welfare value of 368 pounds (95% CI 318, 419). The results highlight a societal view that the severity of chemotherapy-related anaemia will significantly affect cancer patients' HR-QOL. The DCE survey shows that the public value favourably the attributes of treatment with recombinant erythropoietin, and indicates a likely patient preference for treatment with recombinant erythropoietin over blood transfusion.

Not all “quality-adjusted life years” are equal

Background There is evidence that utility elicitation methods used in the calculation of quality-adjusted life years (QALYs) yield different results. It is not clear how these differences impact economic evaluations. Methods Using a mathematical model incorporating data on efficacy, costs, and utility values, we simulated the experiences of 100,000 hypothetical rheumatoid arthritis patients over 10 years (50,000 exposed to infliximab plus methotrexate [MTX] and 50,000 exposed to MTX alone). QALYs, were derived from the Health Utilities Index 2 and 3 (HUI2 and HUI3), the Short Form 6-D (SF-6D), and the Euroqol 5-D (EQ-5D). Incremental cost-utility ratios were determined using each instrument to calculate QALYs and the results were compared using cost-effectiveness acceptability curves. Results Using the different utility measurement methods, the mean difference in QALYs between the infliximab plus MTX and MTX groups ranged from a high of 1.95 QALYs (95% CI = 1.93–1.97) using the HUI3 to 0.89 QALYs (95% CI = 0.88–0.91) using the SF-6D. Adopting the commonly cited value of society's willingness to pay for a QALY of $50,000, 91% of the simulations favored the cost utility of infliximab plus MTX when using the HUI3 to calculate QALYs. However, when using the EQ-5D, HUI2, or the SF-6D utility values to calculate QALYS, the proportion of simulations that favored the cost utility of infliximab were 63%, 45%, and 12%, respectively. Conclusion Depending on the method for determining utility values used in the calculation of QALYs, very different incremental cost-utility ratios are generated.

Trends in the Measurement of Health Utilities in Published Cost-Utility Analyses

The Panel on Cost-Effectiveness in Health and Medicine recommended the compilation of a catalog of health state utility weights for use in cost-utility analyses (CUAs), and has given methodological recommendations. This study presents an update, through 2001, to our current registry of utility weights (available at http://www.tufts-nemc.org/cearegistry; previously at http://www.hsph.harvard.edu/cearegistry), and documents recent changes in methods used for utility weight elicitation. We searched the English-language medical literature for original CUAs reporting outcomes as cost per quality-adjusted life-year (QALY). Two trained readers independently audited each article, abstracting data on the health state descriptions, corresponding utility weights, methods of elicitation, and sources of the estimates. The utility elicitation methods from 1998 to 2001 were compared with the methods used to obtain utilities before 1998. We identified 306 CUAs published after 1998, reporting 1210 separate health-related utility estimates, bringing the total in our catalog to 2159 weights. Most frequently, health states pertained to the circulatory system and oncology. Methods varied substantially: 36% of authors used direct elicitation (standard gamble, time trade-off or rating scale), 23% used generic health status instruments (EQ-5D, Health Utilities Index, etc.), and 25% estimated weights based on clinical judgment. Community preferences were used in 27% of the values. Compared with pre-1998, utilities published from 1998 to 2001 were more likely to be elicited using a generic instrument, more likely elicited from community samples, and less likely derived from expert opinion, with no formally employed methodology. Increasingly, analysts conducting CUAs are using generic, preference-weighted instruments, and relying on community-based preferences. Our catalog of utility weights provides a useful reference tool for producers and consumers of CUAs, but also highlights the continued need for improvement in methods and transparency.

Health-related quality of life (HRQL) scores reported from parents and their children with chronic illness differed depending on utility elicitation method

Objective To describe the relationship between health-related quality of life (HRQL) as measured by utility when elicited from parents and their children with chronic illness. Study design and setting We enrolled families of children admitted for cancer chemotherapy and those attending outpatient rheumatology, hemophilia and bone marrow transplantation clinics. Children in grade 6 or higher were included. The child's HRQL was rated by parent and child using the Standard Gamble (SG), Visual Analogue Scale (VAS), Time Trade-Off (TTO), and Health Utilities Index Mark 2/3 (HUI2 and HUI3). Results 22 families were included. The mean parent SG was 0.92 ± 0.09, which was similar to the mean SG elicited from their children of 0.92 ± 0.10. The parent and child SG were moderately concordant (ICC = 0.64, 95% CI = 0.30, 0.83; P = .0005). In contrast, TTO scores were not concordant (ICC = 0.14, 95% CI = −0.29, 0.53; P = .3), with parents (mean TTO = 0.77 ± 0.31) rating HRQL worse than children (mean TTO = 0.92 ± 0.11; P = .04). Similarly, the mean parent HUI2 of 0.82 ± 0.22 was lower than the child HUI2 of 0.95 ± 0.07; P = .02 and HUI2 were not concordant (ICC = 0.11, 95% CI = −0.35, 0.53; P = .3) between parents and children. Conclusion Parents and children rate HRQL similarly according to SG, but parents rate HRQL significantly worse using TTO and HUI2.

Making Descriptive Use of Prospect Theory to Improve the Prescriptive Use of Expected Utility

This paper proposes a quantitative modification of standard utility elicitation procedures, such as the probability and certainty equivalence methods, to correct for commonly observed violations of expected utility. Traditionally, decision analysis assumes expected utility not only for the prescriptive purpose of calculating optimal decisions but also for the descriptive purpose of eliciting utilities. However, descriptive violations of expected utility bias utility elicitations. That such biases are effective became clear when systematic discrepancies were found between different utility elicitation methods that, under expected utility, should have yielded identical utilities. As it is not clear how to correct for these biases without further knowledge of their size or nature, most utility elicitations still calculate utilities by means of the expected utility formula. This paper speculates on the biases and their sizes by using the quantitative assessments of probability transformation and loss aversion suggested by prospect theory. It presents quantitative corrections for the probability and certainty equivalence methods. If interactive sessions to correct for biases are not possible, then the authors propose to use the corrected utilities rather than the uncorrected ones in prescriptions of optimal decisions. In an experiment, the discrepancies between the probability and certainty equivalence methods are removed by the authors' proposal.

A psychometric analysis of the measurement level of the rating scale, time trade-off, and standard gamble

A fundamental assumption of utility-based analyses is that patient utilities for health states can be measured on an equal-interval scale. This assumption, however, has not been widely examined. The objective of this study was to assess whether the rating scale (RS), standard gamble (SG), and time trade-off (TTO) utility elicitation methods function as equal-interval level scales. We wrote descriptions of eight prostate-cancer-related health states. In interviews with patients who had newly diagnosed, advanced prostate cancer, utilities for the health states were elicited using the RS, SG, and TTO methods. At the time of the study, 77 initial and 73 follow-up interviews had been conducted with a consecutive sample of 77 participants. Using a Rasch model, the boundaries (Thurstone Thresholds) between four equal score sub-ranges of the raw utilities were mapped onto an equal-interval logit scale. The distance between adjacent thresholds in logit units was calculated to determine whether the raw utilities were equal-interval. None of the utility scales functioned as interval-level scales in our sample. Therefore, since interval-level estimates are assumed in utility-based analyses, doubt is raised regarding the validity of findings from previous analyses based on these scales. Our findings need to be replicated in other contexts, and the practical impact of non-interval measurement on utility-based analyses should be explored. If cost-effectiveness analyses are not found to be robust to violations of the assumption that utilities are interval, serious doubt will be cast upon findings from utility-based analyses and upon the wisdom of expending millions in research dollars on utility-based studies.