Can Independently Elicited Adult- and Child-Perspective Health-State Utilities Explain Priority Setting?

OBJECTIVES

Time trade-off (TTO) utilities for EQ-5D-Y-3L health states valued by adults taking a child's perspective are generally higher than their valuations of the same state for themselves. Ceteris paribus, the use of these utilities in economic evaluation implies that children gain less from treatments returning them to full health for a specified amount of time than adults. In this study, we explore if this implication affects individuals' views of priority-setting choices between treatments for adults and children.

METHODS

We elicited TTO utilities for 4 health states in online interviews, in which respondents valued states for a 10-year-old child and another adult their age. Views on priority setting were studied with person trade-off (PTO) tasks involving the same health states. We tested the ability of the subjects' TTO utilities to predict these societal choices in PTO.

RESULTS

There are no significant differences between adult and child health state valuations in our study, but we do observe a substantial preference for treating children over adults in the PTO task.

CONCLUSIONS

Our findings suggest that perspective-dependent health-state utilities only explain a small part of views on priority setting between adults and children. External equity weights might be useful to better explain the higher priority given to children.

Jumping the Queue:Willingness to Pay for Faster Access to COVID-19 Vaccines in Seven European Countries

INTRODUCTION

Given the initial shortage of vaccines to protect against coronavirus disease 2019 (COVID-19), many countries set up priority lists, implying that large parts of the population had to wait. We therefore elicited the willingness to pay (WTP) for access to two hypothetical COVID-19 vaccines.

METHODS

Respondents were asked how much they would be willing to pay to get an immediate COVID-19 vaccination rather than waiting for one through the public system. We report data collected in January/February 2021 from the European COVID Survey (ECOS) comprising representative samples of the population in Denmark, France, Germany, Italy, Portugal, the Netherlands, and the UK (N = 7068).

RESULTS

In total, 73% (68.5%) of respondents were willing to pay for immediate access to a 100% (60%) effective vaccine, ranging from 66.4% (59.4%) in the Netherlands to 83.3% (81.1%) in Portugal. We found a mean WTP of 54.36 euros (median 37 euros) for immediate access to the 100% effective COVID-19 vaccine and 43.83 euros (median 31 euros) for the 60% effective vaccine. The vaccines' effectiveness, respondents' age, country of residence, income, health state and well-being were significant determinants of WTP. Willingness to be vaccinated (WTV) was also strongly associated with WTP, with lower WTV being associated with lower WTP. A higher perceived risk of infection, higher health risk, more trust in the safety of vaccines, and higher expected waiting time for the free vaccination were all associated with a higher WTP.

CONCLUSION

We find that most respondents would have been willing to pay for faster access to COVID vaccines (jumping the queue), suggesting welfare gains from quicker access to these vaccines. This is an important result in light of potential future outbreaks and vaccines.

The effect of duration and time preference on the gap between adult and child health state valuations in time trade-off

Composite time trade-off (cTTO) utilities have been found to be higher when adults value health states for children than for themselves. It is not clear if these differences reflect adults assigning truly higher utilities to the same health state in different perspectives, or if they are caused by other factors, which are not accounted for in the valuation procedure. We test if the difference between children's and adults' cTTO valuations changes if a longer duration than the standard 10 years is used. Personal interviews with a representative sample of 151 adults in the UK were conducted. We employed the cTTO method to estimate utilities of four different health states, where adults considered states both from their own and a 10-year-old child's perspective, for durations of 10 and 20 years. We corrected the cTTO valuations for perspective-specific time preferences in a separate task, again for both perspectives. We replicate the finding that cTTO utilities are higher for the child perspective than for the adult perspective, although the difference is only significant when controlling for other variables in a mixed effects regression. Time preferences are close to 0 on average, and smaller for children than adults. After correcting TTO utilities for time preferences, the effect of perspective is no longer significant. No differences were found for cTTO tasks completed with a 10- or 20-year duration. Our results suggest that the child-adult gap is partially related to differences in time preferences and, hence, that correcting cTTO utilities for these preferences could be useful.

An experimental investigation of social risk preferences for health

In this paper, we use the risk apportionment technique of Eeckhoudt, Rey and Schlesinger (2007) to study higher order risk preferences for others' health as well as ex-ante and ex-post inequality preferences for social risky distributions, and their interaction. In an experiment on a sample of university students acting as impartial spectators, we observe risk aversion towards social health losses and a dislike of ex-ante inequality. In addition, evidence for ex-post inequality seeking is much weaker than evidence for ex-ante inequality aversion. Because ex-ante inequality aversion is unrelated to risk aversion, we conclude that simple forms of utilitarianism are not relevant for individual judgment of social risk over health. Last, our investigation of precautionary distribution, which would occur when one particular group in the society suffers from background health risk, shows substantial polarization of preferences.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11238-023-09928-w.

Decomposing social risk preferences for health and wealth

This study reports the results of the first artefactual field experiment designed to measure the prevalence of aversion toward different components of social risks in a large and demographically representative sample. We identify social risk preferences for health and wealth for losses and gains, and decompose these attitudes into four different dimensions: individual risk, collective risk, ex-post inequality, and ex-ante inequality. The results of a non-parametric analysis suggest that aversion to risk and inequality is the mean preference for outcomes in health and wealth in the domain of gains and losses. A parametric decomposition of aversion to risk and inequality shows that respondents are averse to ex-post and ex-ante inequality in health and wealth for gains and losses. Likewise, respondents are averse to collective risk, but neutral to individual risk, which highlights the importance of considering different components of social risk preferences when managing social health and wealth risks.

Time and lexicographic preferences in the valuation of EQ-5D-Y with time trade-off methodology

In the valuation of EQ-5D-Y-3L, adult respondents are asked to complete composite time trade-off (cTTO) tasks for a 10-year-old child. Earlier work has shown that cTTO utilities elicited in such a child perspective are generally higher than when adults take their own perspective. We explore how differences in time preference in child and adult perspectives could explain this effect. Furthermore, as cTTO valuation in a child perspective involves explicit consideration of immediate death for a child, we also consider how cTTO utilities could be affected by decision-makers lexicographically avoiding death in children. We report the results of an experiment in which 219 respondents valued 5 health states in both adult and child perspectives with either a standard cTTO or a lead-time TTO only approach, in which immediate death is less focal. Time preferences were measured in both perspectives. Our results suggest that utilities were lower when lead-time TTO, rather than cTTO, was used. We find large heterogeneity in time preference in both perspectives, with predominantly negative time preference. The influence of time preferences on utilities, however, was small, and correcting for time preferences did not reduce differences between utilities elicited in both perspectives. Surprisingly, we found more evidence for differences in utilities between adult and child perspectives when lead-time TTO was used. Overall, these results suggest that time and lexicographic preferences affect time trade-off valuation in child and adult perspectives, but are not the explanation for differences between these perspectives. We discuss the implications of our findings for EQ-5D-Y-3L valuation.

Time and lexicographic preferences in the valuation of EQ-5D-Y with time trade-off methodology

In the valuation of EQ-5D-Y-3L, adult respondents are asked to complete composite time trade-off (cTTO) tasks for a 10-year-old child. Earlier work has shown that cTTO utilities elicited in such a child perspective are generally higher than when adults take their own perspective. We explore how differences in time preference in child and adult perspectives could explain this effect. Furthermore, as cTTO valuation in a child perspective involves explicit consideration of immediate death for a child, we also consider how cTTO utilities could be affected by decision-makers lexicographically avoiding death in children. We report the results of an experiment in which 219 respondents valued 5 health states in both adult and child perspectives with either a standard cTTO or a lead-time TTO only approach, in which immediate death is less focal. Time preferences were measured in both perspectives. Our results suggest that utilities were lower when lead-time TTO, rather than cTTO, was used. We find large heterogeneity in time preference in both perspectives, with predominantly negative time preference. The influence of time preferences on utilities, however, was small, and correcting for time preferences did not reduce differences between utilities elicited in both perspectives. Surprisingly, we found more evidence for differences in utilities between adult and child perspectives when lead-time TTO was used. Overall, these results suggest that time and lexicographic preferences affect time trade-off valuation in child and adult perspectives, but are not the explanation for differences between these perspectives. We discuss the implications of our findings for EQ-5D-Y-3L valuation.

The formation of physician altruism

We study how patient-regarding altruism is formed by medical education. We elicit and structurally estimate altruistic preferences using experimental data from a large sample of medical students (N = 733) in Germany at different progress stages in their studies. The estimates reveal substantial heterogeneity in altruistic preferences of medical students. Patient-regarding altruism is highest for freshmen, significantly declines for students in the course of medical studies, and tends to increase again for last year students, who assist in clinical practice. Also, patient-regarding altruism is higher for females and positively associated to general altruism. Altruistic medical students have gained prior practical experience in healthcare, have lower income expectations, and are more likely to choose surgery and pediatrics as their preferred specialty.

Reference-dependent age weighting of quality-adjusted life years

People do not only care about maximizing health gains but also about their distribution. For example, they give more weight to younger patients than older patients. This pilot study aims to investigate if age weighting is reinforced by loss aversion if young people are falling behind one's perceived 'normal' quality of life (QoL), while older people do not. We apply a person trade-off method in a large representative sample (n = 990) to estimate age weighting factors. We also measure QoL levels that individuals regard as 'normal' for different ages, serving as reference points. We observe a considerable amount of age weighting, with 20-year-old patients on average receiving 1.7 times as much weight as 80-year-old patients. Perceived 'normal' QoL rapidly decreases with age of a patient. Older people are more optimistic about what constitutes 'normal QoL' than younger people, but they express a faster decline in normal QoL due to aging. Respondents who view all improvements to be gain enlarging show the least age weighting, but loss aversion cannot explain the results. Still, one's age-related reference level is an important predictor of age weights. Given the explorative nature of this study, further studies are called for to generate more robust evidence.

The Role of Perceived Utility of Full Health in Age Weighting

OBJECTIVES

People often give different weights to quality-adjusted life-years (QALYs) gained by different socioeconomic groups. It is well known that QALY gains of younger patients generally get more weight than the same QALY gains accruing to older patients. This study aims to separate these age-related preferences into "pure age weighting" and age weighting caused by full health not perceived as being the same for the old as for the young.

METHODS

We apply a person trade-off method in a large sample representative (N = 500) of the Dutch general adult population to estimate age weighting factors. We describe health as a percentage of what is considered full health for a given age, for which we obtain a proxy in a separate task.

RESULTS

A high amount of age weighting is observed, with QALYs to 20-year-old patients receiving approximately 1.5 times as much weight as QALYs to 80-year-old patients. At the same time, we see that individuals do not perceive full health to be the same for young and older people. In fact, the age weighting disappears once we control for these differences in full health perceptions.

CONCLUSIONS

Respondents had strong preferences for the young relative to the old, but these preferences were related to full health perceptions, that is, more weight being assigned to younger because full health is at a higher absolute level for them than for the old.

Correcting for discounting and loss aversion in composite time trade-off

Time trade-off utilities have been suggested to be biased upwards. This bias is a result of the method being applied assuming linear utility of life duration, which is violated when individuals discount future life years or are loss averse for health. Applying a "corrective approach", that is, measuring individuals' discount function and loss aversion and correcting time trade-off utilities for these individual characteristics, may reduce this bias in utilities. Earlier work has developed this approach for time trade-off in a student sample. In this study, the corrective approach was extended to composite time trade-off (cTTO) methodology, which enabled correcting utilities for health states worse than dead. In digital interviews a sample of 150 members of the general public completed cTTO tasks for six health states, and afterward they completed measurements of loss aversion and discounting. cTTO utilities were corrected using these measurements under multiple specifications. Respondents were also asked to reflect on and adjust their cTTO utilities directly. Our results show considerable loss aversion and both positive and negative discounting were prevalent. As predicted, correction generally resulted in lower utilities. This was in accordance with the direction of adjustments made by respondents themselves.

Eliciting risk preferences that predict risky health behavior: A comparison of two approaches

Information on attitudes to risk could increase understanding of and explain risky health behaviors. We investigate two approaches to eliciting risk preferences in the health domain, a novel "indirect" lottery elicitation approach with health states as outcomes and a "direct" approach where respondents are asked directly about their willingness to take risks. We compare the ability of the two approaches to predict health-related risky behaviors in a general adult population. We also investigate a potential framing effect in the indirect lottery elicitation approach. We find that risk preferences elicited using the direct approach can better predict health-related risky behavior than those elicited using the indirect approach. Moreover, a seemingly innocuous change to the framing of the lottery question results in significantly different risk preference estimates, and conflicting conclusions about the ability of the indicators to predict risky health behaviors.

Multivariate risk preferences in the quality-adjusted life year model

The interest in multivariate and higher-order risk preferences has increased. A growing body of literature has demonstrated the relevance and impact of these preferences, but for health the evidence is lacking. We measure multivariate and higher-order risk preferences for quality of life (QoL) and longevity, the two attributes of the Quality-Adjusted Life Year (QALY) model. We observe preferences for a positive correlation between these attributes and for pooling together a fixed loss in one of the attributes and a mean-zero risk in the other, and for pooling together mean-zero risks in QoL and longevity. The findings indicate that higher-order risk preferences are stronger for health than for money. Furthermore, we test if preferences for a risky treatment for a disease affecting only QoL, depend on life expectancy. We find no such a relation, but there is a positive relation between riskiness of a comorbidity affecting life expectancy and risk aversion for a QoL treatment. We therefore observe no definitive deviation from the QALY model, although the model is more robust when expected longevity is high. Our findings suggest that the current practice of cost-effectiveness analysis should be generalized to account for risk aversion in QoL and longevity, and higher-order preferences.

Altruism and the Link to Pro-social Pandemic Behavior

In the Corona pandemic, especially in the phase before vaccines were available, people's risk of infection with COVID-19 was dependent on the adherence to pandemic behaviors (e. g., wearing masks) of others around them. To explore whether altruistic individuals are more likely to engage in pro-social behaviors to protect others during the pandemic, we use data from the European COVID Survey (ECOS). The data was collected in September 2020 and consisted of a representative sample from seven European countries (N = 7,025). Altruism was measured as a deviation from purely self-interested behavior by asking respondents how much they would be willing to donate from an unexpected gain to the equivalent of 1000€. Respondents who were willing to donate more than 0 Euros (68.7%) were treated as altruistic; on average, respondents were willing to donate 11.7% (SD 17.9) of the gain. Controlling for country, sociodemographics, general risk aversion and COVID-specific risk aversion, we find that individuals classified as altruistic were more likely to behave pro-socially. More specifically, we find that altruistic respondents were more likely to wait at home for test results and wear a mask where it is recommended. They would also stay about 1 day longer under quarantine without symptoms after visiting a high-risk country and were less likely to go to a supermarket with COVID symptoms. We find no significant effect for wearing a mask in places where it is mandatory and for inviting more than six people into the house. Furthermore, we find that the subjective risk assessment of COVID-19 also plays a role in these behaviors. Our results support evidence from the literature that suggests that adherence to pro-social pandemic behaviors may be increased if public health officials emphasize the altruistic nature of these behaviors.

Self vs. other, child vs. adult. An experimental comparison of valuation perspectives for valuation of EQ-5D-Y-3L health states

OBJECTIVES

EQ-5D-Y-3L health states are valued by adults taking the perspective of a 10-year-old child. Compared to valuation of adult EQ-5D instruments, this entails two changes to the perspective: (i) child health states are valued instead of adult health states and: (ii) health states are valued for someone else instead of for oneself. Although earlier work has shown that these combined changes yield different values for child and adult health states that are otherwise equal, it currently remains unclear why. Hence, we aimed to disentangle the effects of both changes.

METHODS

A sample of 205 students (mean age: 19.48) was surveyed. Each respondent completed visual analogue scale (VAS) and time trade-off (TTO) tasks for five EQ-5D-Y-3L states, using four randomly ordered perspectives: (i) self-adult (themselves), (ii) other-adult (someone their age), (iii) self-child (themselves as a 10-year-old), (iv) other-child (a child of 10 years old). We compared how each perspective impacted outcomes, precision and quality of EQ-5D-Y-3L valuation.

RESULTS

Overall, differences between perspectives were consistent, with their direction being dependent on the health states and respondents. For VAS, the effect on outcomes of valuation depended on severity, but variance was higher in valuation with child perspectives. For TTO, we observed that EQ-5D-Y-3L states valued on behalf of others (i.e., children or adults) received higher valuations, but lower variances.

CONCLUSION

The use of a different perspective appears to yield systematic differences in EQ-5D-Y-3L valuation, with considerable heterogeneity between health states and respondents. This may explain mixed findings in earlier work.

Life satisfaction: The role of domain-specific reference points

In the evaluation of well-being, it is not only important what people have in absolute terms, but also how this compares to reference points in relative terms. We explore the relevance of relative comparisons by testing the effect of people's self-rated position on potential reference points for income and health on their subjective well-being. We used Multiple Discrepancies Theory as a framework to identify seven potentially relevant reference points for income and health. A representative sample (N = 550) of the Netherlands assessed their income and health relative to these reference points. In addition, we elicited monthly household income, health status (EQ-5D-5L), and subjective well-being (SWLS). In line with the literature, we found a negative convex relationship between subjective well-being and age and a positive relationship with being employed, income, and health. For income, subjective well-being was also associated with how current income compared to respondents' needs and progression over time, and for health especially with how current health compared to what they felt they deserved. Our findings suggest that income and health are important for subjective well-being both in absolute and relative terms. We found negative effects on life satisfaction if some of the domain specific reference points were not met.

Trust me; I know what I am doing investigating the effect of choice list elicitation and domain-relevant training on preference reversals in decision making for others

One core assumption of standard economic theory is that an individual's preferences are stable, irrespective of the method used to elicit them. This assumption may be violated if preference reversals are observed when comparing different methods to elicit people's preferences. People may then prefer A over B using one method while preferring B over A using another. Such preference reversals pose a significant problem for theoretical and applied research. We used a sample of medical and economics students to investigate preference reversals in the health and financial domain when choosing patients/clients. We explored whether preference reversals are associated with domain-relevant training and tested whether using guided 'choice list' elicitation reduces reversals. Our findings suggest that preference reversals were more likely to occur for medical students, within the health domain, and for open-ended valuation questions. Familiarity with a domain reduced the likelihood of preference reversals in that domain. Although preference reversals occur less frequently within specialist domains, they remain a significant theoretical and practical problem. The use of clearer valuation procedures offers a promising approach to reduce preference reversals.

Beliefs and Risk Perceptions About COVID-19: Evidence From Two Successive French Representative Surveys During Lockdown

BACKGROUND

The outbreak of COVID-19 has been a major interrupting event, challenging how societies and individuals deal with risk. An essential determinant of the virus' spread is a series of individual decisions, such as wearing face masks in public space. Those decisions depend on trade-offs between costs (or benefits) and risks, and beliefs are key to explain these.

METHODS

We elicit beliefs about the COVID-19 pandemic during lockdown in France by means of surveys asking French citizens about their belief of the infection fatality ratio (IFR) for COVID-19, own risk to catch the disease, risk as perceived by others, and expected prevalence rate. Those self-assessments were measured twice during lockdown: about 2 weeks after lockdown started and about 2 weeks before lockdown ended. We also measured the quality of these beliefs with respect to available evidence at the time of the surveys, allowing us to assess the calibration of beliefs based on risk-related socio-demographics. Finally, comparing own risk to expected prevalence rates in the two successive surveys provides a dynamic view of comparative optimism with respect to the disease.

RESULTS

The risk perceptions are rather high in absolute terms and they increased between the two surveys. We found no evidence for an impact of personal experience with COVID-19 on beliefs and lower risk perceptions of the IFR when someone in the respondent's family has been diagnosed with a disease. Answers to survey 1 confirmed this pattern with a clear indication that respondents were optimistic about their chances to catch COVID-19. However, in survey 2, respondents revealed comparative pessimism.

CONCLUSION

The results show that respondents overestimated the probabilities to catch or die from COVID-19, which is not unusual and does not necessarily reflect a strong deviation from rational behavior. While a rational model explains why the own risk to catch COVID-19 rose between the two surveys, it does not explain why the subjective assessment of the IFR remained stable. The comparative pessimism in survey 2 was likely due to a concomitant increase in the respondents' perceived chances to catch the disease and a decreased expected prevalence rate.

What is it going to be, TTO or SG? A direct test of the validity of health state valuation

Standard gamble (SG) typically yields higher health state valuations than time trade-off (TTO), which may be caused by biases affecting both methods. It has been suggested that TTO yields more accurate health state valuations, because TTO is subject to both upward and downward biases that may cancel out. Verifying this claim, however, would require a golden standard to test validity against. In this study, we attempted to provide a first direct test of the validity of health state valuation. A total of 119 students completed five TTO and SG tasks. Afterwards, their health state valuations elicited with TTO and SG were shown to them in an interactive graph. Respondents were asked to indicate which of the methods represented their valuation of a health state best. They could also adjust their valuation. Overall, we found that respondents indicated that TTO valuations better reflected health state valuations, a result that was more pronounced for more severe health states. When offered the opportunity, on average, respondents adjusted health state valuations downwards. These findings may have implications for future work on (bias correction in) health state valuations.

Living up to expectations: Experimental tests of subjective life expectancy as reference point in time trade-off and standard gamble

Earlier work suggested that subjective life expectancy (SLE) functions as reference point in time trade-off (TTO), but has not tested or modelled this explicitly. In this paper we construct a model based on prospect theory to investigate these predictions more thoroughly. We report the first experimental test of reference-dependence with respect to SLE for TTO and extend this approach to standard gamble (SG). In two experiments, subjects' SLEs were used to construct different versions of 10-year TTO and SG tasks, with the gauge duration either described as occurring above or below life expectation. Our analyses suggest that both TTO and SG weights were affected by SLE as predicted by prospect theory with SLE as reference point. Subjects gave up fewer years in TTO and were less risk-tolerant in SG below SLE, implying that weights derived from these health state valuation methods for durations below SLE will be biased upwards.

A comparison of individual and collective decision making for standard gamble and time trade-off

Quality-Adjusted Life-Years (QALYs) are typically derived from individual preferences over health episodes. This paper reports the first experimental investigation into the effects of collective decision making on health valuations, using both time trade-off (TTO) and standard gamble (SG) tasks. We investigated collective decision making in dyads, by means of a mixed-subjects design where we control for learning effects. Our data suggest that collective decision making has little effect on decision quality, as no effects were observed on decision consistency and monotonicity for both methods. Furthermore, QALY weights remained similar between individual and collective decisions, and the typical difference in elicited weights between TTO and SG was not affected. These findings suggest that consulting with others has little effect on health state valuation, although learning may have. Additionally, our findings add to the literature of the effect of collective decision making, suggesting that no such effect occurs for TTO and SG.

Good things come to those who wait-Decreasing impatience for health gains and losses

Historically, time preferences are modelled by assuming constant discounting, which implies a constant level of impatience. The prevailing empirical finding, however, is decreasing impatience (DI), meaning that levels of impatience decrease over time. Theoretically, such changes in impatience are crucial to understand behavior and self-control problems. Very few methods exist to measure DI without being restricted to or confounded by certain assumptions about the discounting function or utility curve. One such measure is the recently introduced DI-index, which has been applied to both monetary and health outcomes. The DI-index quantifies the deviation from constant impatience and is flexible enough to capture both increasing and decreasing impatience. In this study, we apply the DI-index to measure impatience for health outcomes in a reference-dependent framework. That is, we measure impatience for both health gains and health losses compared to a reference-point, in individual and societal settings, using a within-subjects design (n = 98). We allowed for both positive and negative discounting, since negative discounting has been observed for losses (i.e. preferring to incur losses earlier rather than later) in earlier work. To capture changes in time inconsistency when subjects show negative discounting (i.e. patience), we modify the DI-index to a decreasing (im)patience (DIP)-index, which can be applied without loss of generality. As in earlier work, we observe large heterogeneity in time consistency; i.e., a mix of decreasing, increasing and constant (im)patience. Across all DIP-indices elicited, increasing impatience was the modal preference for those satisfying impatience, and decreasing patience for those satisfying patience. No systematic differences were observed between health gains and losses or between societal and individual outcomes. This suggests that for health outcomes both patient and impatient individuals assign more importance to time differences delayed further in the future.

Rabin's paradox for health outcomes

Many health economic studies assume expected utility maximisation, with typically a concave utility function to capture risk aversion. Given these assumptions, Rabin's paradox (RP) involves preferences over mixed gambles yielding moderate outcomes, where turning down such gambles imply absurd levels of risk aversion. Although RP is considered a classic critique of expected utility, no paper has as of yet fully tested its preferences within individuals. In an experiment we report a direct test of RP in the health domain, which was previously only considered in the economic literature, showing it may have pervasive implications here too. Our paper supports the shift towards alternative, empirically valid models, such as prospect theory, also in the health domain. These alternative models are able to accommodate Rabin's paradox by allowing reference-dependence and loss aversion.

QALYs without bias? Nonparametric correction of time trade-off and standard gamble weights based on prospect theory

Common health state valuation methodologies, such as standard gamble (SG) and time trade-off (TTO), typically produce different weights for identical health states. We attempt to alleviate these differences by correcting the confounding influences modeled in prospect theory: loss aversion and probability weighting. Furthermore, we correct for nonlinear utility of life duration. In contrast to earlier attempts at correcting TTO and SG weights, we measure and correct all these tenets simultaneously, using newly developed nonparametric methodology. These corrections were applied to three less-than-perfect health states, measured with TTO and SG. We found considerable loss aversion and probability weighting for both gains and losses in life years, and we observe concave utility for gains and convex utility for losses in life years. After correction, the initially significant differences in weights between TTO and SG disappeared for all health states. Our findings suggest new opportunities to account for bias in health state valuations but also the need for further validation of resulting weights.

The Corrective Approach: Policy Implications of Recent Developments in QALY Measurement Based on Prospect Theory

BACKGROUND AND OBJECTIVES

Common health state valuation methodology, such as time tradeoff (TTO) and standard gamble (SG), is typically applied under several descriptively invalid assumptions, for example, related to linear quality-adjusted life years (QALYs) or expected utility (EU) theory. Hence, the current use of results from health state valuation exercises may lead to biased QALY weights, which may in turn affect decisions based on economic evaluations using such weights. Methods have been proposed to correct responses for the biases associated with different health state valuation techniques. In this article we outline the relevance of prospect theory (PT), which has become the dominant descriptive alternative to EU, for health state valuations and economic evaluations.

METHODS AND RESULTS

We provide an overview of work in this field, which aims to remove biases from QALY weights. We label this "the corrective approach." By quantifying PT parameters, such as loss aversion, probability weighting, and nonlinear utility, it may be possible to correct TTO and SG responses for biases in an attempt to produce more valid estimates of preferences for health states. Through straightforward examples, this article illustrates the effects of this corrective approach and discusses several unresolved issues that currently limit the relevance of corrected weights for policy.

CONCLUSIONS

Suggestions for research addressing these issues are provided. Nonetheless, if validly corrected health state valuations become available, we argue in favor of using these in economic evaluations.

A QALY loss is a QALY loss is a QALY loss: a note on independence of loss aversion from health states

Evidence has accumulated documenting loss aversion for monetary and, recently, for health outcomes-meaning that, generally, losses carry more weight than equally sized gains. In the conventional Quality-Adjusted Life Year (QALY) models, which comprise utility for quality and length of life, loss aversion is not taken into account. When measuring elements of the QALY model, commonly, the (implicit) assumption is that utility for length and quality of life are independent. First attempts to quantify loss aversion for QALYs typically measured loss aversion in the context of life duration, keeping quality of life constant (or vice versa). However, given that QALYs are multi-attribute utilities, it may be possible that the degree of loss aversion is dependent on, or inseparable from, quality of life and non-constant. We test this assumption using non-parametric methodology to quantify loss aversion, under different levels of quality of life. We measure utility of life duration for four health states within subjects, and present the results of a robustness test of loss aversion within the QALY model. We find loss aversion coefficients to be stable at the aggregate level, albeit with considerable heterogeneity at the individual level. Implications for applied work on prospect theory within health economics are discussed.

[Loss is gain? Discarding TNF-α inhibitors]

According to a recent study, stopping the prescription of TNF inhibitors is a cost-effective decision at various willingness-to-accept thresholds. Discontinuing the prescription of the drug may lead to a minor loss in health - expressed in quality adjusted life years - but results in significant societal savings. In our commentary, we stress that willingness-to-pay thresholds should not be completely replaced by the willingness-to-accept threshold, also when it concerns health losses. Loss aversion can be viewed as either a relevant societal phenomenon or an irrationality that should not guide decision making.

Measuring multivariate risk preferences in the health domain

We investigate univariate and multivariate risk preferences for health (longevity) and wealth. We measure attitudes toward correlation and attitudes toward higher order dependence structures such as cross-prudence and cross-temperance, making use of the risk apportionment technique proposed by Eeckhoudt et al. (2007). For multivariate gains, we find correlation aversion and cross-prudence in longevity and wealth. For losses, we observe correlation seeking and cross-imprudence. We do not find clear evidence for cross-temperance. Our results indicate that longevity and wealth are considered to be substitutes for gains, but not for losses. Second, univariate (higher order) risk preferences are comparable for longevity and wealth, although somewhat closer to linearity for wealth. Third, we find evidence that attitudes toward dependence structures in the health domain are sign-dependent.

Ambiguity preferences for health

In most medical decisions, probabilities are ambiguous and not objectively known. Empirical evidence suggests that people's preferences are affected by ambiguity. Health economic analyses generally ignore ambiguity preferences and assume that they are the same as preferences under risk. We show how health preferences can be measured under ambiguity, and we compare them with health preferences under risk. We assume a general ambiguity model that includes many of the ambiguity models that have been proposed in the literature. For health gains, ambiguity preferences and risk preferences were indeed the same. For health losses, they differed with subjects being more pessimistic in decision under ambiguity. Utility and loss aversion were the same for risk and ambiguity. Our results imply that reducing the clinical ambiguity of health losses has more impact than reducing the ambiguity of health gains, that utilities elicited with known probabilities may not carry over to an ambiguous setting, and that ambiguity aversion may impact value of information analyses if losses are involved. These findings are highly relevant for medical decision making, because most medical interventions involve losses.

Peer effects in health valuation: the relation between rating of contemporaries' health and own health

Background

Most health valuation studies assume that individuals’ health valuations do not depend on social comparisons. However, there is some evidence that this assumption is not satisfied in practice. This paper tests whether self-rated health by means of a Visual Analogue Scale (VAS) is related to how one perceives the health of one’s contemporaries, while accounting for one’s health as classified by the EQ-5D classification system.

Methods

In a large sample (n = 1500), representative of the general public, we use a VAS to rate respondents’ own health and their assessment of their contemporaries’ health. In addition, we directly ask them whether they perceive their health to be better, the same, or worse than their contemporaries, and we measure their own health according to the EQ-5D-5 L.

Results

We find a positive relationship between own health rating and contemporaries’ health rating, after controlling for the respondents’ own health as classified according to the EQ-5D. Furthermore, we observe a discrepancy between relative health vis-à-vis age peers as measured by an ordinal comparison and relative health as measured by a VAS. Finally, respondents, especially women, tended to overestimate the health of other people of their age.

Conclusions

We provide evidence that people’s own health rating is related to the perception of health of contemporaries. Our results indicate that knowledge about a respondent’s perception of others’ health is useful in explaining health state valuations.

Discounting in Economic Evaluations

Appropriate discounting rules in economic evaluations have received considerable attention in the literature and in national guidelines for economic evaluations. Rightfully so, as discounting can be quite influential on the outcomes of economic evaluations. The most prominent controversies regarding discounting involve the basis for and height of the discount rate, whether costs and effects should be discounted at the same rate, and whether discount rates should decline or stay constant over time. Moreover, the choice for discount rules depends on the decision context one adopts as the most relevant. In this article, we review these issues and debates, and describe and discuss the current discounting recommendations of the countries publishing their national guidelines. We finish the article by proposing a research agenda.

New findings from the time trade-off for income approach to elicit willingness to pay for a quality adjusted life year

In this paper we empirically investigate how to appropriately model utility of wealth and health. We use a recently proposed alternative approach to value willingness to pay (WTP) for health, making use of trade-offs between income and life years or quality of life, which we extend to allow for a more realistic multiplicative utility function over health and money. Moreover, we show how reference-dependency can be incorporated into this model and derive its predictions for WTP elicitation. We propose three experimental elicitation procedures and test these in a feasibility study, analysing the responses under different assumptions about the discount rate. Several interesting results are reported: first, the data are highly skewed, but if we trim the 5% lowest and highest values, we obtain plausible WTP estimates. Second, the results differ considerably between procedures, indicating that WTP estimates are sensitive to the assumed utility function. Third, respondents appear to be loss averse for both health and money, which is consistent with assumptions from prospect theory. Finally, our results also indicate that respondents are more willing to trade quality of life than life years.

Discounting health and money: New evidence using a more robust method

This study compares discounting for money and health in a field study. We applied the direct method, which measures discounting independent of utility, in a representative French sample, interviewed at home by professional interviewers. We found more discounting for money than for health. The median discount rates (6.5% for money and 2.2% for health) were close to market interest rates, suggesting that at the aggregate level the direct method solves the puzzle of unrealistically high discount rates typically observed in applied economics. Constant discounting fitted the data better than the hyperbolic discounting models that we considered. The substantial individual heterogeneity in discounting was correlated with age and occupation.

Are Health State Valuations from the General Public Biased? A Test of Health State Reference Dependency Using Self-assessed Health and an Efficient Discrete Choice Experiment

Health state valuations of patients and non-patients are not the same, whereas health state values obtained from general population samples are a weighted average of both. The latter constitutes an often-overlooked source of bias. This study investigates the resulting bias and tests for the impact of reference dependency on health state valuations using an efficient discrete choice experiment administered to a Dutch nationally representative sample of 788 respondents. A Bayesian discrete choice experiment design consisting of eight sets of 24 (matched pairwise) choice tasks was developed, with each set providing full identification of the included parameters. Mixed logit models were used to estimate health state preferences with respondents' own health included as an additional predictor. Our results indicate that respondents with impaired health worse than or equal to the health state levels under evaluation have approximately 30% smaller health state decrements. This confirms that reference dependency can be observed in general population samples and affirms the relevance of prospect theory in health state valuations. At the same time, the limited number of respondents with severe health impairments does not appear to bias social tariffs as obtained from general population samples. Copyright © 2016 John Wiley & Sons, Ltd.

[Economic insights into promoting healthy behaviour: the pros and cons of a financial incentive]

Recent studies have shown that financial incentives help to promote a healthier lifestyle; these include better adherence to medication, taking more exercise and quitting smoking. Although this is in accordance with economic theory, it also raises objections. Firstly, it may be considered too paternalistic, secondly it raises health care costs, and thirdly it creates ethical dilemmas. In this commentary I argue that it may still be worthwhile to implement these incentives. Moreover, I use insights from behavioural economics to provide a number of recommendations on promoting healthy behaviour in a more cost-effective way, while taking into account the resulting ethical issues.

Exploring a new method for deriving the monetary value of a QALY

Several studies have sought to determine the monetary value of health gains expressed as quality adjusted life years (QALYs) gained, predominantly using willingness to pay approaches. However, willingness to pay has a number of recognized problems, most notably its insensitivity to scope. This paper presents an alternative approach to estimate the monetary value of a QALY, which is based on the time trade-off method. Moreover, it presents the results of an online study conducted in the Netherlands exploring the feasibility of this novel approach. The results seem promising, but also highlight a number of methodological problems with this approach, most notably nontrading and the elicitation of negative values. Additional research is necessary to try to overcome these problems and to determine the potential of this new approach.

An elicitation of utility for quality of life under prospect theory

This paper performs several tests of decision analysis applied to the health domain. First, we conduct a test of the normative expected utility theory. Second, we investigate the possibility to elicit the more general prospect theory. We observe risk aversion for gains and losses and violations of expected utility. These results imply that mechanisms governing decisions in the health domain are similar to those in the monetary domain. However, we also report one important deviation: utility is universally concave for the health outcomes used in this study, in contrast to the commonly found S-shaped utility for monetary outcomes, with concave utility for gains and convex utility for losses.

Altruistic Preferences in Time Tradeoff

Whether respondents incorporate altruistic preferences in time tradeoff (TTO) exercises remains understudied. We present an extended quality-adjusted life-year model incorporating altruism. We derive that altruism may affect TTO values in 2 directions. First, “longevity altruists” may wish to prolong life for the sake of their loved ones (to avoid being missed). Second, “quality-of-life altruists” may have a preference to avoid bad health states resulting in being a burden to loved ones. The existence and influence of these preferences in a TTO were empirically confirmed in a sample of 1690 respondents from the general public. We classified respondents as “longevity altruists” or “quality-of-life altruists” based on their reasoning behind inclusion of loved ones in their TTO responses. In line with expectations, longevity altruists traded fewer years than quality-of-life altruists. Nonaltruists gave intermediate values.

Estimating sign-dependent societal preferences for quality of life

This paper is the first to apply prospect theory to societal health-related decision making. In particular, we allow for utility curvature, equity weighting, sign-dependence, and loss aversion in choices concerning quality of life of other people. We find substantial inequity aversion, both for gains and losses, which can be attributed to both diminishing marginal utility and differential weighting of better-off and worse-off. There are also clear framing effects, which violate expected utility. Moreover, we observe loss aversion, indicating that subjects give more weight to one group's loss than another group's gain of the same absolute magnitude. We also elicited some information on the effect of the age of the studied group. The amount of inequity aversion is to some extent influenced by the age of the considered patients. In particular, more inequity aversion is observed for gains of older people than gains of younger people.

Incorporating sign-dependence in health-related social welfare functions

It is important to measure people's preferences regarding the trade-off between efficiency and equity in health to make public decisions that are in a society's best interests. This article demonstrates the usefulness of social welfare functions to obtain these measurements. Insights from individual decision making, in particular, prospect theory, turn out to be helpful to estimate societal preferences more accurately. The author shows how one can disentangle the effects of loss aversion in this estimation. The presented approach also allows for sign-dependent societal utility and equity weighting functions. Recent empirical studies that used this approach with choices concerning quality of life of other people reported the presence of substantial inequity aversion both for gains and for losses, as well as loss aversion. Several examples demonstrate the relevance of these insights for preference elicitations and health economic evaluations.

Deriving time discounting correction factors for TTO tariffs

The Time Trade-off (TTO) method is a popular method for valuing health state utilities and is frequently used in economic evaluations. However, this method produces utilities that are distorted by several biases. One important bias entails the failure to incorporate time discounting. This paper aims to measure time discounting for health outcomes in a sample representative for the general population. In particular, we estimate TTO scores alongside time discounting in order to derive a set of correction factors that can be employed to correct raw TTO scores for the downward bias caused by time discounting. We find substantial positive correction factors, which are increasing with the severity of the health state. Furthermore, higher discounting is found when using more severe health states in the discounting elicitation task. More research is needed to further develop discount rate elicitation procedures and test their validity, especially in general public samples. Moreover, future research should investigate the correction of TTO values for other biases as well, such as loss aversion, and to develop a criterion to test the external validity of TTO scores.

Would you rather be ill now, or later?

The time tradeoff (TTO) method is frequently used to calculate the quality adjustment of the quality adjusted life year and is therefore an important element in the calculation of the benefits of medical interventions. New specifications of TTO, known as 'lead time' TTO and 'lag time' TTO, have been developed to overcome methodological issues of the 'classic' TTO. In the lead time TTO, ill-health is explicitly placed in the future, after a period of good health, whereas in lag time TTO, a health state starts immediately and is followed by a 'lag time' of good health. In this study, we take advantage of these timing properties of lead and lag time TTO. In particular, we use data from a previous study that employed lead and lag time TTO to estimate their implied discounting parameters. We show that individuals prefer being ill later, rather than now, with larger per-period discount rates for longer durations of the health states.

Prospect theory in the health domain: a quantitative assessment

It is well-known that expected utility (EU) has empirical deficiencies. Cumulative prospect theory (CPT) has developed as an alternative with more descriptive validity. However, CPT's full function had not yet been quantified in the health domain. This paper is therefore the first to simultaneously measure utility of life duration, probability weighting, and loss aversion in this domain. We observe loss aversion and risk aversion for gains and losses, which for gains can be explained by probabilistic pessimism. Utility for gains is almost linear. For losses, we find less weighting of probability 1/2 and concave utility. This contrasts with the common finding of convex utility for monetary losses. However, CPT was proposed to explain choices among lotteries involving monetary outcomes. Life years are arguably very different from monetary outcomes and need not generate convex utility for losses. Moreover, utility of life duration reflects discounting, causing concave utility.

Time to tweak the TTO: results from a comparison of alternative specifications of the TTO

This article examines the effect that different specifications of the time trade-off (TTO) valuation task may have on values for EQ-5D-5L health states. The new variants of the TTO, namely lead-time TTO and lag-time TTO, along with the classic approach to TTO were compared using two durations for the health states (15 and 20 years). The study tested whether these methods yield comparable health-state values. TTO tasks were administered online. It was found that lag-time TTO produced lower values than lead-time TTO and that the difference was larger in the longer time frame. Classic TTO values most resembled those of the lag-time TTO in a 20-year time frame in terms of mean absolute difference. The relative importance of different domains of health was systematically affected by the duration of the health state. In the tasks with a 10-year health-state duration, anxiety/depression had the largest negative impact on health-state values; in the tasks with a 5-year duration, the pain/discomfort domain had the largest negative impact.

Time trade-off: one methodology, different methods

There is no scientific consensus on the optimal specification of the time trade-off (TTO) task. As a consequence, studies using TTO to value health states may share the core element of trading length of life for quality of life, but can differ considerably on many other elements. While this pluriformity in specifications advances the understanding of TTO from a methodological point of view, it also results in incomparable health state values. Health state values are applied in health technology assessments, and in that context comparability of information is desired. In this article, we discuss several alternative specifications of TTO presented in the literature. The defining elements of these specifications are identified as being either methodological, procedural or analytical in nature. Where possible, it is indicated how these elements affect health state values (i.e., upward or downward). Finally, a checklist for TTO studies is presented, which incorporates a list of choices to be made by researchers who wish to perform a TTO task. Such a checklist enables other researchers to align methodologies in order to enhance the comparability of health state values.

Lead time TTO: leading to better health state valuations?

Preference elicitation tasks for better than dead (BTD) and worse than dead (WTD) health states vary in the conventional time trade-off (TTO) procedure, casting doubt on uniformity of scale. 'Lead time TTO' (LT-TTO) was recently introduced to overcome the problem. We tested different specifications of LT-TTO in comparison with TTO in a within-subject design. We elicited preferences for six health states and employed an intertemporal ranking task as a benchmark to test the validity of the two methods. We also tested constant proportional trade-offs (CPTO), while correcting for discounting, and the effect of extending the lead time if a health state is considered substantially WTD. LT-TTO produced lower values for BTD states and higher values for WTD states. The validity of CPTO varied across tasks, but it was higher for LT-TTO than for TTO. Results indicate that the ratio of lead time to disease time has a greater impact on results than the total duration of the time frame. The intertemporal ranking task could not discriminate between TTO and LT-TTO.

The way that you do it? An elaborate test of procedural invariance of TTO, using a choice-based design

The time tradeoff (TTO) method is often used to derive Quality-Adjusted Life Year health state valuations. An important problem with this method is that results have been found to be responsive to the procedure used to elicit preferences. In particular, fixing the duration in the health state to be valued and inferring the duration in full health that renders an individual indifferent, causes valuations to be higher than when the duration in full health is fixed and the duration in the health state to be valued is elicited. This paper presents a new test of procedural invariance for a broad range of time horizons, while using a choice-based design and adjusting for discounting. As one of the known problems with the conventional procedure is the violation of constant proportional tradeoffs (CPTO), we also investigate CPTO for the alternative TTO procedure. Our findings concerning procedural invariance are rather supportive for the TTO procedure. We find no violations of procedural invariance except for the shortest gauge duration. The results for CPTO are more troublesome: TTO scores depend on gauge duration, reinforcing the evidence reported when using the conventional procedure.