Prospect theory in the health domain: a quantitative assessment

Risk preferences over health: Empirical estimates and implications for medical decision-making

Mainstream health economic theory implies that an expected gain in health-related quality of life (HRQoL) produces the same value for consumers, regardless of baseline health. Several strands of recent research call this implication into question. Generalized Risk-Adjusted Cost-Effectiveness (GRACE) demonstrates theoretically that baseline health status influences value, so long as consumers are not risk-neutral over health. Prior empirical literature casts doubt on risk-neutral expected utility-maximization in the health domain. We estimate utility over HRQoL in a nationally representative U.S. population and use our estimates to measure risk preferences over health. We find that individuals are risk-seeking at low levels of health, become risk-averse at health equal to 0.485 (measured on a 0-1 scale), and are most risk-averse at perfect health (coefficient of relative risk aversion = 4.51). We develop the resulting implications for medical decision making, cost-effectiveness analyses, and the proper theory of health-related decision making under uncertainty.

Uncertainty: a neglected determinant of health behavior?

Health behaviors are critical determinants of the well-being of individuals and populations, and understanding the determinants of these behaviors has been a major focus of research. One important determinant that has received little direct attention in past health research is uncertainty: a complex phenomenon that pertains not only to scientific issues regarding the diagnosis, prognosis, prevention, and treatment of health problems, but also to personal issues regarding other important health-related concerns. Here, we make the case for greater attention to uncertainty in health behavior theory and research, and especially to personal uncertainties. We discuss three exemplary types of personal uncertainty-value uncertainty, capacity uncertainty, and motive uncertainty-which relate, respectively, to moral values, capacities to enact or change behaviors, and the motives and intentions of other persons or institutions. We argue that that personal uncertainties such as these influence health behaviors, but their influence has historically been obscured by a focus on other constructs such as self-efficacy and trust. Reconceptualizing and investigating health behavior as a problem of uncertainty can advance both our understanding of the determinants of healthy behaviors and our ability to promote them.

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.

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.

Decision thresholds with genetic testing

A genetic test is a test for the presence or absence of a genetic mutation. A positive test outcome that reveals a mutation associated with increased risk for a disease may lead a patient to seek preventive treatment provided that the penetrance (probability of developing the disease given the mutation) is sufficiently high. We derive the test threshold and the test-treatment threshold, which confine the mutation probability interval for the use of the genetic test. Test and treatment costs as well as a low penetrance rate of the mutation narrow this interval. We illustrate the model with parameters of the test for BRCA1 and BRCA2 genes as well as of preventive treatment options for breast cancer.

A Group Emergency Decision-Making Method for Epidemic Prevention and Control Based on Probabilistic Hesitant Fuzzy Prospect Set Considering Quality of Information

Epidemics can bring huge impacts to economic operation and human health, a practical and effective emergency decision-making (EDM) method is of great significance to reduce all kinds of losses and slow the spread of epidemics. In the process of EDM, decision information is usually uncertain and vague, and the psychological behaviors and various perspectives of decision makers (DMs) should be considered. Hence, this paper develops a group emergency decision-making (GEDM) method under risk based on the probabilistic hesitant fuzzy set (PHFS) and cumulative prospect theory (CPT), in which probabilistic hesitant fuzzy prospect set (PHFPS) that combines PHFS and CPT is developed to portray the vagueness of decision information and psychologies of DMs. Moreover, experts’ creditability in evaluation criteria is generally different because of the differences of their own knowledge structures, practical experience, individual preference and so on. A formula is proposed to measure the quality of decision information provided by experts for revising the expert weights. In addition, the evaluation criteria supporting the GEDM of epidemics are given. Finally, the proposed method is demonstrated by an empirical case study of COVID-19, and the comparison analysis based on the rank-biased overlap model and the sensitivity analysis are conducted to the illustrate the validity of the proposed method.

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.

Expect Nothing: The (Lack of) Influence of Subjective Life Expectancy on Valuation of Child Health States

Objective

Earlier research has shown that individuals' subjective life expectancy (SLE) affects health state valuation with time trade-off (TTO). Individuals with longer expected life durations are less willing to trade-off life duration, which yields higher utilities. In this article, the influence of SLE is explored in the valuation of EQ-5D-Y-3L with a proxy perspective, i.e., adults' valuation of health states considering the life of a 10-year-old child. As SLE for children is likely higher, this might explain earlier findings suggesting that individuals are less willing to trade-off years of life for children than for adults.

Methods

A total of 197 respondents were recruited to take part in digital TTO interviews, facilitated by trained interviewers. TTO interviews were implemented in accordance with the recommended protocol for the valuation of EQ-5D-Y-3L. Respondents valued 10 EQ-5D-Y-3L health states for a 10-year-old child, after which they were asked to report how old they themselves expected to become and also how old they expected a 10-year-old child to become.

Results

Generally, adult respondents reported higher SLE for children than for themselves. Neither SLE was systematically associated with the willingness to trade lifetime or the number of life years traded off in TTO tasks. This null-result was substantiated by regression analyses per health state.

Conclusion

The results of this study suggest that individuals' expectations about longevity are not associated with EQ-5D-Y-3L valuation. This lack of association is in contrast to earlier work and might be explained by the psychological distance introduced with proxy perspective valuation, or by the methodological differences with earlier work.

Application of an economic evaluation approach to making regulatory decisions regarding access to medicines: advantages, challenges and recommendations

Initially patients require a prescription to access most new medicines. Some medicines may later be reclassified, allowing patients to access them without a prescription. Currently, Australian Therapeutic Goods Administration guidelines regarding reclassification decisions focus on patient risk rather than on potential benefits to patient health and the healthcare system. We conducted two extensive case studies demonstrating an economic evaluation approach to medicine reclassification in Australia, which were presented at various conferences and to key stakeholders. This article discusses the advantages and challenges of using an economic evaluation approach to inform medicine reclassification decisions. Advantages identified include systematically and transparently synthesising evidence from multiple sources; predicting the overall expected impact of reclassification on health outcomes and costs before it occurs; considering a broader range of risks and benefits; aggregation of health impacts into a single measure (quality-adjusted life years); identification of drivers of uncertainty; insight into the effects of different regulatory decisions; and improved consistency of evidence. Challenges include data availability and quality, estimating behavioural changes, model complexity, the lack of an incremental cost-effectiveness ratio threshold, and funding of economic analyses. We recommend that regulatory decision makers use an economic evaluation approach to help inform reclassification decisions, although economic evaluation results should be considered as part of the broader body of evidence. Ultimately, the use of an economic evaluation approach will contribute to helping decision makers maximise population health outcomes in an efficient way.What is known about the topic?In the past, decisions regarding medicine reclassification have generally been made using a deliberative approach focusing on patient risk. However, there are also potential benefits to patient health and effects on the healthcare system. Increasing awareness of these benefits have led to the development of alternative approaches to decision making, including an economic evaluation approach.What does this paper add?This article discusses the advantages and challenges of using an economic evaluation approach to inform medicine reclassification decisions compared with alternative approaches.What are the implications for practitioners?Economic evaluation results should be considered as part of the broader body of evidence regarding the types of health impacts, the extent of the available evidence, who will be affected, and the role of medical practitioners and pharmacists in mitigating any risks. However, awareness of the advantages and challenges of this approach in advance will help mitigate some of the challenges and increase acceptance of the economic evaluation results by decision makers and stakeholders.

Lay, professional, and artificial intelligence perspectives on risky medical decisions and COVID-19: How does the number of lives matter in clinical trials framed as gains versus losses?

Outcomes of clinical trials need to be communicated effectively to make decisions that save lives. We investigated whether framing can bias these decisions and if risk preferences shift depending on the number of patients. Hypothetical information about two medicines used in clinical trials having a sure or a risky outcome was presented in either a gain frame (people would be saved) or a loss frame (people would die). The number of patients who signed up for the clinical trials was manipulated in both frames in all the experiments. Using an unnamed disease, lay participants (experiment 1) and would-be medical professionals (experiment 2) were asked to choose which medicine they would have administered. For COVID-19, lay participants were asked which medicine should medical professionals (experiment 3), artificially intelligent software (experiment 4), and they themselves (experiment 5) favour to be administered. Broadly consistent with prospect theory, people were more risk-seeking in the loss frames than the gain frames. However, risk-aversion in gain frames was sensitive to the number of lives with risk-neutrality at low magnitudes and risk-aversion at high magnitudes. In the loss frame, participants were mostly risk-seeking. This pattern was consistent across laypersons and medical professionals, further extended to preferences for choices that medical professionals and artificial intelligence programmes should make in the context of COVID-19. These results underscore how medical decisions can be impacted by the number of lives at stake while revealing inconsistent risk preferences for clinical trials during a real pandemic.

Loss Aversion and Health Behaviors: Results from Two Incentivized Economic Experiments

Experimental research in health economics has analyzed the effects of economic preference parameters such as risk attitude and time preference on the probability of adopting risky health behaviors. However, the existing evidence is mixed and previous research often fails to include controls for other determinants of health behaviors such as personality traits. The aim of this research is to analyze the relationships between an incentivized measure of loss aversion and three health behaviors: smoking, binge drinking, and engaging in physical activity. Loss aversion is a preference measure that has been derived from prospect theory as an alternative approach to analyze decision-making under risk, such as the decision to invest in health capital, and has never been used in an analysis of the determinants of health behaviors before. Using two experimental samples of college students in the Republic of Korea and the United States of America, and controlling for Big Five personality traits and a host of individual-level control variables, there are no statistically significant relationships between loss aversion and the three aforementioned health behaviors, but relationships for Big Five conscientiousness, extraversion, agreeableness, and neuroticism. A candidate explanation might be lack of domain independence for loss aversion. Differences between the Korean and the US samples indicate the possibility of intercultural differences.

Evaluation of the development ability of medical association based on evidential reasoning and prospect theory

China has proposed medical couplet body to alleviate residents’ difficulties in seeking medical treatment, and the future development ability of medical couplet body has gradually become a research interest. On the basis of prospect theory, this study constructs a comprehensive evaluation index system with qualitative and quantitative indexes, clear hierarchy, and diverse attribute characteristics. The development ability of medical couplet body is also comprehensively and systematically evaluated. In addition, the evidential reasoning method is proposed on the basis of the equivalent transformation of prospect value. Furthermore, the validity and feasibility of the model are proven through experiments, and the influence of decision makers’ risk attitude on the evaluation results is discussed.

Learning decision thresholds for risk stratification models from aggregate clinician behavior

Using a risk stratification model to guide clinical practice often requires the choice of a cutoff—called the decision threshold—on the model’s output to trigger a subsequent action such as an electronic alert. Choosing this cutoff is not always straightforward. We propose a flexible approach that leverages the collective information in treatment decisions made in real life to learn reference decision thresholds from physician practice. Using the example of prescribing a statin for primary prevention of cardiovascular disease based on 10-year risk calculated by the 2013 pooled cohort equations, we demonstrate the feasibility of using real-world data to learn the implicit decision threshold that reflects existing physician behavior. Learning a decision threshold in this manner allows for evaluation of a proposed operating point against the threshold reflective of the community standard of care. Furthermore, this approach can be used to monitor and audit model-guided clinical decision making following model deployment.

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.

Behavioural Economics and Human Decision Making: Instances from the Health Care System

Over the last two decades behavioural economics has gained much momentum among scholars because of its innovative and controversial ways of explaining processes and mechanisms underpinning individuals' judgements and decision making. Thanks to these features, behavioural economics has been applied to diversified domains, namely finance, public choice and marketing. Although the intrinsic characteristics of the health care sector, ranging from incomplete and asymmetrical information to high frequency of critical choices, make the sector a fertile ground for behavioural economics applications, research on the influences of behavioural economics on health care and clinical decision making are still rather fragmented. Therefore, through an interdisciplinary literature review integrating behavioural economics research with medical and behavioural decision-making studies, this article contributes to behavioural decision-making literature by providing a wide overview of how behavioural economics strategies may impact, and be implemented in, diverse health care circumstances. Examples of behavioural economics applications to health care circumstances include: organ donation and transplantation; habitual choices; individuals' loss aversion and trust; present-biased preference; decision fatigue and excessive choice. Hence, this article aims to promote the effective behaviour of both consumers and providers in health care.

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.

Unbiased assessment of disease surveillance utilities: A prospect theory application

Objectives

We contribute a new methodological approach to the ongoing efforts towards evaluating public health surveillance. Specifically, we apply a descriptive framework, grounded in prospect theory (PT), for the evaluation of decisions on disease surveillance deployment. We focus on two attributes of any surveillance system: timeliness, and false positive rate (FPR).

Methods

In a sample of 69 health professionals from a number of health related networks polled online, we elicited PT preferences, specifically respondents’ attitudes towards gains, losses and probabilities (i.e., if they overweight or underweight extreme probabilities) by means of a series of lotteries for either timeliness or FPR. Moreover, we estimated willingness to pay (WTP) for improvements in the two surveillance attributes. For contextualization, we apply our framework to rabies surveillance.

Results

Our data reveal considerable probability weighting, both for gains and losses. In other words, respondents underestimate their chances of getting a good outcome in uncertain situations, and they overestimate their chances of bad outcomes. Moreover, there is convex utility for losses and loss aversion, that is, losses loom larger than gains of the same absolute magnitude to the respondents. We find no differences between the estimated parameters for timeliness and FPR. The median WTP is $7,250 per day gained in detection time and $30 per 1/10,000 reduction in FPR.

Conclusion

Our results indicate that the biases described by PT are present among public health professionals, which highlights the need to incorporate a PT framework when eliciting their preferences for surveillance systems.

In this paper we contribute a new methodological approach to the ongoing efforts towards evaluating public health surveillance. Specifically, we apply a descriptive framework for the evaluation of decisions on disease surveillance deployment. We focus on two attributes of any surveillance system: timeliness and false positive rates. In a sample of 69 health professionals from a number of health related networks polled online, we elicited preferences, specifically respondents’ attitudes towards gains, losses and probabilities (i.e., if they overweight or underweight extreme probabilities) by means of a series of lotteries. For contextualization, we apply our framework to rabies surveillance. Our data reveal that respondents underestimate their chances of getting a good outcome in uncertain situations, and they overestimate their chances of bad outcomes. Moreover, losses loom larger than gains of the same absolute magnitude to the respondents. We find no differences between the estimated parameters for timeliness and false positive rates. Our results indicate that the biases described are present among public health professionals, and highlight the need to adjust for them when eliciting their preferences for surveillance systems.

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.

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.

Predicting Cancer-Prevention Behavior: Disentangling the Effects of Risk Aversion and Risk Perceptions

Experimental and survey research spanning the last two decades concludes that people who are more risk tolerant are more likely to engage in risky health activities such as smoking and heavy alcohol consumption, and are more likely to be obese. Subjective perceptions of the risk associated with different activities have also been found to be associated with health behaviors. While there are numerous studies that link risk perceptions with risky behavior, it is notable that none of these controls for risk aversion. Similarly, studies that control for risk aversion fail to control for risk misperceptions. We use a survey of 474 men and women to investigate the influence of risk aversion, risk misperceptions, and cognitive ability on the choice to engage in behaviors that either increase or mitigate cancer risk. We measure optimism in two dimensions: baseline optimists are those who inaccurately believe their cancer risk to be below its expert-assessed level, while control optimists are those who believe they can reduce their risk of cancer (by changing their lifestyle choices) to a greater extent than is actually the case. Our results indicate that baseline optimism is significantly and negatively correlated with subjects' tendencies to engage in cancer-risk-reducing behaviors, and positively correlated with risky behaviors. Subjects' control misperceptions also appear to play a role in their tendency to engage in risky and prevention behaviors. When controlling for both of these types of risk misperception, risk aversion plays a much smaller role in determining health behaviors than found in past studies.

Risk attitudes of people with 'manageable' chronic disease: An analysis under prospect theory

Health promotion interventions can be improved using methods from behavioural economics to identify and target specific decision-making biases at the individual level. In this context, prospect theory provides a suitable framework within which decision-making processes can be operationalised. Focusing on a trade-off between health outcomes and behaviour change incurred by chronic disease management (lifestyle change, or 'self-management'), we are the first to measure the risk attitudes and quantify the full utility function under prospect theory of a patient population. We conducted a series of hypothetical elicitations over health outcomes associated with different self-management behaviours from a population of individuals with or without 'manageable' chronic disease (n = 120). We observed risk aversion in both the gain and the loss domains, as well as significant loss aversion. There seems to be an age effect on risk attitudes in this context, with younger people being on average less risk averse than older people. Our work addresses a need to better understand these decision-making processes, so that behaviour change interventions tailored to specific patient populations can be improved.

Predicting medical practices using various risk attitude measures

This paper investigates the predictive power of several risk attitude measures on a series of medical practices. We elicit risk preferences on a sample of 1500 French general practitioners (GPs) using two different classes of tools: scales, which measure GPs' own perception of their willingness to take risks between 0 and 10; and lotteries, which require GPs to choose between a safe and a risky option in a series of hypothetical situations. In addition to a daily life risk scale that measures a general risk attitude, risk taking is measured in different domains for each tool: financial matters, GPs' own health, and patients' health. We take advantage of the rare opportunity to combine these multiple risk attitude measures with a series of self-reported or administratively recorded medical practices. We successively test the predictive power of our seven risk attitude measures on eleven medical practices affecting the GPs' own health or their patients' health. We find that domain-specific measures are far better predictors than the general risk attitude measure. Neither of the two classes of tools (scales or lotteries) seems to perform indisputably better than the other, except when we concentrate on the only non-declarative practice (prescription of biological tests), for which the classic money-lottery test works well. From a public health perspective, appropriate measures of willingness to take risks may be used to make a quick, but efficient, profiling of GPs and target them with personalized communications, or interventions, aimed at improving practices.

Nudging people with Type 2 diabetes towards better self-management through personalized risk communication: A pilot randomized controlled trial in primary care

OBJECTIVES

To assess the feasibility in routine primary care consultation and investigate the effect on risk recall and self-management of a new type of risk communication intervention based on behavioural economics ("nudge-based") for people with Type 2 diabetes mellitus (T2DM).

METHODS

Forty adults with poorly controlled T2DM (HbA1c > 7.5%) were randomized to receive a personalized, nudge-based risk communication intervention (n = 20) or standard care (n = 20). Risk recall and self-management were evaluated at baseline and 12 weeks after the intervention.

RESULTS

Both in terms of feasibility and acceptability, this new risk communication intervention was very satisfactory. Study retention rate after 12 weeks was very high (90%) and participants were highly satisfied with the intervention (4.4 out of 5 on the COMRADE scale). Although not powered to identify significant between-group effects, the intervention significantly improved risk recall after 12 weeks and intentions to make lifestyle changes (dietary behaviour) compared to standard care.

CONCLUSIONS

This pilot study provides the first evidence of the feasibility of implementing in primary care a nudge-based risk communication intervention for people with T2DM. Based on the promising results observed, an adequately powered trial to determine the effectiveness of the intervention on long-term self-management is judged feasible. As a result of this feasibility study, some minor adaptations to the intervention and study methods that would help to facilitate a definitive trial are also reported.

Uncertainty and the Undervaluation of Services for Severe Health States in Cost-Utility Analyses

OBJECTIVES

To test the hypothesis that the "severity effect"-the preference for more than utility-maximizing expenditure on severe health states-may be the result of, or exacerbated by, the uncertainty associated with the chance of contracting the illness that causes the severe health state.

METHODS

Survey respondents were asked to imagine that they will contract one of two illnesses and asked to allocate a budget between two insurance policies, each of which provides services for the treatment of one of the illnesses. A person's final health state varied with the amount of insurance purchased for the illness that occurred and therefore with the level of treatment. The relative cost of the two policies was altered and the selected levels of insurance compared with the levels that would be provided by a health authority that sought to maximize total utility or quality-adjusted life-years from its own budget.

RESULTS

Respondents selected more than utility-maximizing insurance for protection against severe health states. A number of psychological factors that affect measurement under uncertainty do not affect utility as currently measured. This difference may explain the present results and also explain the "severity paradox" that personal preferences as presently measured imply less expenditure on severe health states than do "social preferences" for the treatment of strangers.

CONCLUSIONS

Uncertainty alters preferences. Incorporating these preferences in decision making would result in greater spending on severe health states.

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.

Adherence of patients with type 2 diabetes mellitus to medications: the role of risk preferences

OBJECTIVE

To examine whether risk tolerance is associated with adherence to oral hypoglycemic agents (OHAs).

METHODS

We performed a cross-sectional study among adult patients with type 2 diabetes mellitus (n = 308) presenting for routine out-patient visits, using validated questionnaires to estimate: risk preferences (risk-seeking, risk averse, risk neutral), motivation, self-efficacy, impulsivity, perception of the disease and of the interpersonal process of care, demographic and socioeconomic characteristics; computerized patient medical records to estimate disease severity and a computerized database for retrieval of medication adherence, 1 year before the interview. Adherence was estimated using prescription-based measures of proportion of days covered (PDC). Concurrent adherence was calculated as: PDC with ≥1 OHAs; average PDC; PDC of ≥80% for all OHAs.

RESULTS

Multivariable ordered logit model revealed that compared to others, risk-seeking patients had lower PDC with ≥1 OHAs (β = -0.50, p ≤ .1). Specifically, risk-seeking patients were 11.2 percentage points less likely to have ≥80% of the follow-up period covered with ≥1 OHAs available (p ≤ .1). In addition, risk-seeking patients had lower average PDC (β = -0.85, p ≤ .05). Specifically, these patients were 19.5 percentage points less likely to have an average PDC of ≥80% (p ≤ .05). Multivariable logistic model revealed that risk-seeking was associated with lower probability of having PDC ≥80% for all OHAs in the follow-up period (OR; 90% CI: 0.59; 0.35-0.97).

CONCLUSIONS

Risk-seeking patients are less adherent to OHA medications. Identifying these patients may enable practitioners to proactively tailor strategies to improve their adherence and health outcomes.

Risk attitudes in medical decisions for others: An experimental approach

The aim of this paper is to investigate how risk attitudes in medical decisions for others vary across health contexts. A lab experiment was designed to elicit the risk attitudes of 257 medical and nonmedical students by assigning them the role of a physician who must decide between treatments for patients. An interval regression model was used to estimate individual coefficients of relative risk aversion, and an estimation model was used to test for the effect of type of medical decision and experimental design characteristics on elicited risk aversion. We find that (a) risk attitudes vary across different health contexts, but risk aversion prevails in all of them; (b) students enrolled in health-related degrees show a higher degree of risk aversion; and (c) real rewards for third parties (patients) make subjects less risk-averse. The results underline the importance of accounting for attitudes towards risk in medical decision making.

Considering the CPR Decision Through the Lens of Prospect Theory in the Context of Advanced Chronic Illness

It is common for people with advanced chronic illness to have many health care providers and many health care-related visits. It is also common, during those visits, to be asked whether attempts at cardiopulmonary resuscitation (CPR) are desired, in the event of cardiac arrest. Although the question is common, the implications of a "yes" or a "no" may not be well understood. Although CPR can be a life-saving procedure, it is not always in the patient's best interest. This article discusses experiences with CPR of 2 older women (and their adult children) during their last years of life, and uses concepts from prospect theory to make suggestions for changes in the way health care providers and patients approach advance care planning including the CPR decision.

Potential determinants of deductible uptake in health insurance: How to increase uptake in The Netherlands?

In health insurance, voluntary deductibles are offered to the insured in return for a premium rebate. Previous research has shown that 11 % of the Dutch insured opted for a voluntary deductible (VD) in health insurance in 2014, while the highest VD level was financially profitable for almost 50 % of the population in retrospect. To explain this discrepancy, this paper identifies and discusses six potential determinants of the decision to opt for a VD from the behavioral economic literature: loss aversion, risk attitude, ambiguity aversion, debt aversion, omission bias, and liquidity constraints. Based on these determinants, five potential strategies are proposed to increase the number of insured opting for a VD. Presenting the VD as the default option and providing transparent information regarding the VD are the two most promising strategies. If, as a result of these strategies, more insured would opt for a VD, moral hazard would be reduced.

The value of disease prevention vs treatment

We present an integrated valuation model for diseases that are life-threatening. The model extends the standard one-period value-per-statistical-life model to three health prospects: healthy, ill, and dead. We derive willingness-to-pay values for prevention efforts that reduce a disease's incidence rate as well as for treatments that lower the corresponding health deterioration and mortality rates. We find that the demand value of prevention always exceeds that of treatment. People often overweight small risks and underweight large ones. We use the rank dependent utility framework to explore how the demand for prevention and treatment alters when people evaluate probabilities in a non-linear manner. For incidence and mortality rates associated with common types of cancers, the inverse-S shaped probability weighting found in experimental studies leads to a significant increase in the demand values of both treatment and prevention.

Adherence to Self-Care Behaviors among Patients with Type 2 Diabetes-The Role of Risk Preferences

OBJECTIVES

To examine whether the degree of risk aversion is associated with adherence to disease self-management among adults with type 2 diabetes.

METHODS

This was a cross-sectional study of patients with type 2 diabetes (n = 408) aged 21 to 70 years who presented for routine visits in the diabetes clinic at a university medical center in Beer-Sheva, Israel. The authors used validated questionnaires to estimate adherence, risk preferences, motivation, self-efficacy, impulsivity, perceptions about the disease and the interpersonal process of care, and demographic and socioeconomic characteristics, in addition to retrieving data from computerized patient medical records of clinical indicators of disease severity. Multivariable linear and ordered-logit models examined predictors of adherence to each self-care behavior.

RESULTS

Multivariable analyses revealed that, compared with others, risk-seeking patients reported lower general adherence (β = -0.32; P ≤ 0.05), and specifically, lower adherence to healthful eating plan (β = -0.48; P ≤ 0.1), consumption of low-fat food (β = -0.47; P ≤ 0.1), exercise (β = -0.73; P ≤ 0.05), blood glucose monitoring (β = -0.69; P ≤ 0.05), and foot care (β = -0.36; P ≤ 0.1). Risk-seeking patients did not report lower consumption of fruits and vegetables (β = -0.19; P > 0.1). Because 96% of the study population reported optimal adherence to medication, determinants of this behavior could not be analyzed.

CONCLUSIONS

Risk preference is associated with adherence to self-care behaviors. Identifying risk seekers may enable practitioners to target these patients with tailored strategies to improve adherence, thus more efficiently allocating scarce health care resources.

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.

In Sickness but Not in Wealth

We present results from a hypothetical framed field experiment assessing whether risk preferences significantly differ across the health and financial domains when they are elicited through the same multiple price list paired-lottery method. We consider a sample of 300 patients attending outpatient clinics in a university hospital in Athens during the Greek financial crisis. Risk preferences in finance were elicited using paired-lottery questions with hypothetical payments. The questions were adapted to the health domain by framing the lotteries as risky treatments in hypothetical health care scenarios. Using maximum likelihood methods, we estimated the degree of risk aversion, allowing for the estimates to be dependent on domain and individual characteristics. The subjects in our sample, who were exposed to both health and financial distress, tended to be less risk averse in the financial domain than in the health domain.

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.

Preferences for Analgesic Treatments Are Influenced by Probability of the Occurrence of Adverse Effects and the Time to Reach Maximal Therapeutic Effects

Research on shared medical decision-making suggested that both the potency of a treatment and the probability of it being successful influence individual treatment preferences. Patients also need to consider the negative attributes of treatments, such as the occurrence of adverse effects or a slow start to the therapeutic effects. It remains unclear how these attributes influence individual treatment preferences. We investigated how the analgesic effect, the adverse effect, and the time-course effect influenced the preference of analgesic treatments. Forty-five healthy volunteers participated in three hypothetical analgesic decision-making tasks. They were instructed to imagine that they were experiencing pain and choose between two hypothetical analgesic treatments: the more potent radical treatment and the less potent conservative treatment. The potency of a treatment was countered by the following attributes: the probability of working successfully, the probability of inducing an adverse effect, and the time required for the treatment to reach its maximal effect. We found that (a) when the overall probability that a treatment would induce an adverse effect decreased, the participants changed their preference from a conservative treatment to a radical treatment; (b) when the time-course for a treatment to reach its maximal effect was shortened, the participants changed their preference from a conservative treatment to a radical treatment, and (c) individual differences in prior clinical pain and the degree of imagined pain relief were associated with preferences. The findings showed that the adverse effects and the time course of treatments guide the analgesic treatment preferences, highlighting the importance of sharing information about negative attributes of treatments in pain management. The findings imply that patients may over-emphasize the occurrence of adverse effect or a slow time-course of treatment effect. In terms of shared medical decision-making, clinicians should clarify these negative attributes related to treatment to patients.

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.