Jose Luis Pinto-Prades

Resolving Inconsistencies in Utility Measurement Under Risk: Tests of Generalizations of Expected Utility

This paper explores inconsistencies that occur in utility measurement under risk when expected utility theory is assumed and the contribution that prospect theory and some other generalizations of expected utility can make to the resolution of these inconsistencies. We used five methods to measure utilities under risk and found clear violations of expected utility. Of the theories studied, prospect theory was the most consistent with our data. The main improvement of prospect theory over expected utility was in comparisons between a riskless and a risky prospect (riskless-risk methods). We observed no improvement over expected utility in comparisons between two risky prospects (risk-risk methods). An explanation for the latter observation may be that there was less distortion in probability weighting in the interval [0.10, 0.20] than has commonly been observed.

Valuing QALYs at the end of life

The possibility of weighting QALYs differently for different groups of patients has been a source of debate. Most recently, this debate has been extended to the relative value of QALYs at the end of life (EoL). The objective of this study is to provide evidence of societal preferences in relation to this topic. Three cross-sectional surveys were conducted amongst Spanish general population (n = 813). Survey 1 compared increases in life expectancy for EoL patients with health gains from temporary health problems. Survey 2 compared health gains for temporary health problems with quality of life gains at the EoL (palliative care). Survey 3 compared increases in life expectancy with quality of life gains, both for EoL patients. Preferences were elicited using Person Trade-Off (PTO) and Willingness to pay (WTP) techniques presenting two different durations of health benefit (6 and 18 months). Health benefits, measured in QALYs, were held constant in all comparisons. In survey 1 mean WTP was higher for life extending treatments than for temporary health problems and the majority of respondents prioritised life extension over temporary health problems in response to the PTO questions. In survey 2 mean WTP was higher for palliative care than for temporary health problems and 83% prioritized palliative care (for both durations) in the PTO questions. In survey 3 WTP values were higher for palliative care than for life extending treatments and more than 60% prioritized palliative care in the PTO questions. Our results suggest that QALYs gained from EoL treatments have a higher social value than QALYs gained from treatments for temporary health problems. Further, we found that people attach greater weight to improvements in quality of life than to life extension at the end of life.

The predictive validity of prospect theory versus expected utility in health utility measurement

Most health care evaluations today still assume expected utility even though the descriptive deficiencies of expected utility are well known. Prospect theory is the dominant descriptive alternative for expected utility. This paper tests whether prospect theory leads to better health evaluations than expected utility. The approach is purely descriptive: we explore how simple measurements together with prospect theory and expected utility predict choices and rankings between more complex stimuli. For decisions involving risk prospect theory is significantly more consistent with rankings and choices than expected utility. This conclusion no longer holds when we use prospect theory utilities and expected utilities to predict intertemporal decisions. The latter finding cautions against the common assumption in health economics that health state utilities are transferable across decision contexts. Our results suggest that the standard gamble and algorithms based on, should not be used to value health.

MORE EVIDENCE OF THE PLATEAU EFFECT : A SOCIAL PERSPECTIVE

The purpose of this study was to test the existence of the plateau effect at the social level. The authors tried to confirm the preliminary conclusion that people may not be willing to trade off any longevity to improve the health state of a large number of people if the health states are mild enough. They tested this assumption using the person- tradeoff technique. They also used a parametric approach and a nonparametric ap proach to study the relationship between individual and social values. Results show the existence of the plateau effect in the context of resource allocation. Furthermore, with the nonparametric approach, a plateau effect in the middle part of the scale was also observed, suggesting that social preference may not be directly predicted from individual utilities. The authors caution against the possible framing effects that may be present in these kinds of questions. Key words: person tradeoffs; social prefer ences ; utility assessments; plateau effect. (Med Decis Making 1998;18:287-294)

Handling Data Quality Issues to Estimate the Spanish EQ-5D-5L Value Set Using a Hybrid Interval Regression Approach.

BACKGROUND The Spanish five-level EuroQol five-dimensional questionnaire (EQ-5D-5L) valuation study was the first to use the EuroQol Valuation Technology protocol, including composite time trade-off (C-TTO) and discrete choice experiments (DCE). In this study, its investigators noticed that some interviewers did not fully explain the C-TTO task to respondents. Evidence from a follow-up study in 2014 confirmed that when interviewers followed the protocol, the distribution of C-TTO responses widened. OBJECTIVES To handle the data quality issues in the C-TTO responses by estimating a hybrid interval regression model to produce a Spanish EQ-5D-5L value set. METHODS Four different models were tested. Model 0 integrated C-TTO and DCE responses in a hybrid model and models 1 to 3 altered the interpretation of the C-TTO responses: model 1 allowed for censoring of the C-TTO responses, whereas model 2 incorporated interval responses and model 3 included the interviewer-specific protocol violations. For external validation, the predictions of the four models were compared with those of the follow-up study using the Lins concordance correlation coefficient. RESULTS This stepwise approach to modeling C-TTO and DCE responses improved the concordance between the valuation and follow-up studies (concordance correlation coefficient: 0.948 [model 0], 0.958 [model 1], 0.952 [model 2], and 0.989 [model 3]). We recommend the estimates from model 3, because its hybrid interval regression model addresses the data quality issues found in the valuation study. CONCLUSIONS Protocol violations may occur in any valuation study; handling them in the analysis can improve external validity. The resulting EQ-5D-5L value set (model 3) can be applied to inform Spanish health technology assessments.

Health economic decision-making: a comparison between UK and Spain

OBJECTIVE This review examines the impact of economic evaluation in informing national or local policies within both jurisdictions. We focus on the factors that have made the economic evaluation evolves differently in both settings. AREAS OF AGREEMENT Economic evaluation facilitates decision-making regarding the efficiency of interventions. The existence of national or local bodies regulating the process has contributed to increasing its use in decision-making and the development of its methods. AREAS OF CONTROVERSY Cost-effectiveness approach is based on the assumption of health maximization subject to a budget constraint. Decision-makers are not only interested in health maximization alone. This may result in policy-makers failing to consider economic evaluations into their allocation decisions. AREAS TO DEVELOP RESEARCH: Methods that incorporate wider decision-makers goals (mainly local) and research to study the real impact of economic evaluation in terms of improved efficiency and equity are particularly required.

Does the Introduction of the Ranking Task in Valuation Studies Improve Data Quality and Reduce Inconsistencies? The Case of the EQ-5D-5L

BACKGROUND Time trade-off (TTO)-based valuation studies for the three-level version of the EuroQol five-dimensional questionnaire (EQ-5D) typically started off with a ranking task (ordering the health states by preference). This was not included in the protocol for the five-level EQ-5D (EQ-5D-5L) valuation study. OBJECTIVES To test whether reintroducing a ranking task before the composite TTO (C-TTO) could help to reduce inconsistencies in C-TTO responses and improve the data quality. METHODS Respondents were randomly assigned to three study arms. The control arm was the present EQ-5D-5L study protocol, without ranking. The second arm (ranking without sorting) preceded the present protocol by asking respondents to rank the target health states using physical cards. The states were then valued in random order using C-TTO. In the third arm (ranking and sorting), the ranked states remained visible through the C-TTO tasks and the order of valuation was determined by the ranking. The study used only 10 EQ-5D-5L health states. We compared the C-TTO-based inconsistent pairs of health states and ties. RESULTS The final sample size was 196 in the control arm, 205 in the ranking without sorting arm, and 199 in the ranking and sorting arm. The percentages of ties by respondents were 15.1%, 12.5%, and 12.6% for the control arm, the ranking without sorting arm, and the ranking and sorting arm, respectively. The extra cost for adding the ranking task was about 15%. CONCLUSIONS The benefit does not justify the effort involved in the ranking task. For this reason, the addition of the ranking task to the present EQ-5D-5L valuation protocol is not an attractive option.

Exploring Differences between TTO and DCE in the Valuation of Health States

There is recent interest in using discrete choice experiments (DCEs) to derive health state utility values, and results can differ from time tradeoff (TTO). Clearly, DCE is “choice based,” whereas TTO is generally considered a “matching” task. We explore whether procedural adaptations to the TTO, which make the method more closely resemble a DCE, make TTO and choice converge. In particular, we test whether making the matching procedure in TTO less “transparent” to the respondent reduces disparities between TTO and DCE. We designed an interactive survey that was hosted on the Internet, and 2022 interviews were achieved in the United Kingdom in a representative sample of the population. We found a marked divergence between TTO and DCE, but this was not related to the “transparency” of the TTO procedure. We conclude that a difference in the error structure between TTO and choice and that factors other than differences in utility are affecting choices is driving the divergence. The latter has fundamental implications for the way choice data are analyzed and interpreted.

Comment on “A Model of Probabilistic Choice Satisfying First-Order Stochastic Dominance” by Pavlo Blavatskyy

We present examples of existing evidence that lead us to be cautious about claims made in the original paper [Blavatskyy PR 2011 A model of probabilistic choice satisfying first-order stochastic dominance. Management Sci. 573:542--548] that the proposed model provides a better fit to experimental data than do existing models. We raise concerns about the accuracy of this and other assertions and about the adequacy of the comparisons made with alternative models in the existing literature. This paper was accepted by Rakesh Sarin, decision analysis.

The Lead Time Tradeoff The Case of Health States Better Than Dead

Background. Lead time tradeoff (L-TTO) is a variant of the time tradeoff (TTO). L-TTO introduces a lead period in full health before illness onset, avoiding the need to use 2 different procedures for states better and worse than dead. To estimate utilities, additive separability is assumed. We tested to what extent violations of this assumption can bias utilities estimated with L-TTO. Methods. A sample of 500 members of the Spanish general population evaluated 24 health states, using face-to-face interviews. A total of 188 subjects were interviewed with L-TTO and the rest with TTO. Both samples evaluated the same set of 24 health states, divided into 4 groups with 6 health states per set. Each subject evaluated 1 of the sets. A random effects regression model was fitted to our data. Only health states better than dead were included in the regression since it is in this subset where additive separability can be tested clearly. Results. Utilities were higher in L-TTO in relation to TTO (on average L-TTO adds about 0.2 points to the utility of health states), suggesting that additive separability is violated. The difference between methods increased with the severity of the health state. Thus, L-TTO adds about 0.14 points to the average utility of the less severe states, 0.23 to the intermediate states, and 0.28 points to the more severe estates. Conclusions. L-TTO produced higher utilities than TTO. Health problems are perceived as less severe if a lead period in full health is added upfront, implying that there are interactions between disjointed time periods. The advantages of this method have to be compared with the cost of modeling the interaction between periods.