Ana Bobinac

Erasmus Universiteit Rotterdam, Rotterdam, South Holland, Netherlands

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Publications (11)19.47 Total impact

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    ABSTRACT: There is an increased interest in the monetary value of a quality-adjusted life-year (QALY). Past studies commonly derived willingness to pay (WTP) for certain future QALY gains. However, obtaining valid WTP per QALY estimates proved to be difficult. We conducted a contingent valuation study and estimated the individual WTP per QALY under risk. We demonstrate the impact of probability weighting on WTP per QALY estimates in the Netherlands. Our estimates of the value of a QALY are in the range of 80,000-110,000 when the weighting correction was applied, and 250,500 without correction. The validity of these estimates, applying probability weighting, appears to be good. Given the reasonable support for their validity and practical meaningfulness, the estimates derived while correcting for probability weighting may provide valuable input for the debate on the consumption value of health. While decision makers should not apply these estimates without further consideration, since strictly individual valuations may not carry all relevant information and values for societal decision-making, the current estimates may provide a good and informed basis for further discussion and study of this important topic.
    PharmacoEconomics 11/2013; · 2.86 Impact Factor
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    ABSTRACT: BACKGROUND: A commonly held view of the decision rule in economic evaluations in health care is that the final incremental cost-effectiveness ratio needs to be judged against some threshold, which is equal for all quality-adjusted life-year (QALY) gains. This reflects the assumption that "a QALY is a QALY" no matter who receives it, or the equity notion that all QALY gains are equally valuable, regardless of the context in which they are realized. If such an assumption does not adequately reflect the distributional concerns in society, however, different thresholds could be used for different QALY gains, whose relative values can be seen as "equity weights." AIM: Our aim was to explore the relationship between equity or distributional concerns and the social value of QALYs within the health economics literature. In light of the empirical interest in equity-related concerns as well as the nature and height of the incremental cost-effectiveness ratio threshold, this study investigates the "common ground" between the two streams of literature and considers how the empirical literature estimating the incremental cost-effectiveness ratio threshold treats existing distributional considerations.
    Value in Health 12/2012; 15(8):1119-26. · 2.19 Impact Factor
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    ABSTRACT: Interpreting the outcomes of cost utility analyses requires an appropriately defined threshold for costs per quality-adjusted life year (QALY). A common view is that the threshold should represent the (consumption) value a society attaches to a QALY. So far, individual valuations of personal health gains have mainly been studied rather than potentially relevant social values. In this study, we present the first direct empirical estimates of the willingness to pay for a QALY from a societal perspective. We used the contingent valuation approach, valuing QALYs under uncertainty and correcting for probability weighting. The estimates obtained in a representative sample of the Dutch population (n = 1004) range from €52,000 to €83,000, depending on the specification of the societal perspective. The scale sensitivity was weak, however. Copyright © 2012 John Wiley & Sons, Ltd.
    Health Economics 10/2012; · 2.23 Impact Factor
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    ABSTRACT: Estimates of WTP per QALY can be taken as an indication of the monetary value of health gains, which may carry information regarding the appropriate height of the cost-effectiveness threshold. Given the far-reaching consequences choosing a particular threshold, and thus the potential relevance of WTP per QALY estimates, it is important to address the validity of these estimates. This study addresses this issue. Our findings offer little support to the validity of WTP per QALY estimates obtained in this study. Implications for general WTP per QALY estimates and further research are discussed.
    Journal of Health Economics 10/2011; 31(1):158-68. · 1.60 Impact Factor
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    ABSTRACT: We tested the influence of the growth in life expectancy over time on social time preferences for health. Growing life expectancy of future generations should raise social discount rates for health because of diminishing marginal utility of additional health gains and equity reasons reflecting the desire for a more equitable distribution of benefits over generations. This influence has, however, been largely ignored in empirical studies. We provide a first comprehensive analysis of how time preferences for health gains vary with projected growth rates, indicating the importance of subjective expectations about the growth in life expectancy in the elicitation of social time preference. Six hundred and fifty-six respondents, representative of the Dutch population, completed one of four questionnaires, differing in the projected growth in life expectancy. Results showed that individuals discount future health gains at different rates, depending on the latency period and on the projected or expected growth in life expectancy. As hypothesized, discount rates increased with higher growth rates. The association between observed discount rates and expectations regarding future life expectancy was confirmed, suggesting that discount rates for health may depend on future life expectancy. In light of our results, specifying life expectancy of future generations in time preference exercises appears appropriate.
    Health Economics 01/2011; 20(1):111-9. · 2.23 Impact Factor
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    ABSTRACT: The aim of this study was to elicit the individual willingness to pay (WTP) for a quality-adjusted life-year (QALY). In a Web-based questionnaire containing contingent valuation exercises, respondents valued health changes in five scenarios. In each scenario, the respondents first valued two health states on a visual analog scale (VAS) and expressed their WTP for avoiding a decline in health from the better health state to the worse, using a payment scale followed by a bounded open contingent valuation question. WTP per QALY was calculated for QALY gains calculated using VAS valuations, as well as the Dutch EQ-5D tariffs, the two steps in the WTP estimations and each scenario. Heterogeneity in WTP per QALY ratios was examined from the perspective of: 1) household income; and 2) the level of certainty in WTP indicated by respondents. Theoretical validity was analyzed using clustered multivariate regressions. A total of 1091 respondents, representative of the Dutch population, participated in the survey. Mean WTP per QALY was € 12,900 based on VAS valuations, and € 24,500 based on the Dutch EuroQoL tariffs. WTP per QALY was strongly associated with income, varying from € 5000 in the lowest to € 75,400 in the highest income group. Respondents indicating higher certainty exhibited marginally higher WTP. Regression analyses confirmed expected relations between WTP per QALY, income, and other personal characteristics.   Individual WTP per QALY values elicited in this study are similar to those found in comparable studies. The use of individual valuations in social decision-making deserves attention, however.
    Value in Health 12/2010; 13(8):1046-55. · 2.19 Impact Factor
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    ABSTRACT: Besides patients' health and well-being, healthcare interventions may affect the well-being of significant others. Such 'spill over effects' in significant others may be distinguished in two distinct effects: (i) the caregiving effect and (ii) the family effect. The first refers to the welfare effects of providing informal care, i.e., the effects of caring for someone who is ill. The second refers to a direct influence of the health of a patient on others' well-being, i.e., the effects of caring about other people. Using a sample of Dutch informal caregivers we found that both effects exist and may be comparable in size. Our results, while explorative, indicate that economic evaluations adopting a societal perspective should include both the family and the caregiving effects measured in the relevant individuals.
    Journal of Health Economics 07/2010; 29(4):549-56. · 1.60 Impact Factor
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    ABSTRACT: Increasingly, decisions regarding the allocation of scarce health care resources are (also) based on information regarding the cost-effectiveness of health care interventions. In order to use such information correctly, it is pivotal to have a meaningful threshold against which to judge cost-effectiveness information. A common view is that this threshold should represent some (average) estimation of the willingness to pay (WTP) for health gains (typically expressed as QALYs) in society. Not only are empirical estimates of this value lacking in many jurisdictions, more fundamentally, an important and as yet unanswered question is how to obtain such a monetary value of a QALY in a reliable manner. Recently, a number of studies used contingent analysis to elicit WTP for a QALY. However, there is little research on the validity and reliability of such estimates.This paper elaborately examines the validity of WTP obtained in a study designed to estimate the individual monetary value of a QALY. More specifically, the aim was to (1) inspect the sensitivity of WTP estimates in terms of the size of the gain and duration of health benefits, (2) study the relationship between the WTP and the position of the health gain on the QALY scale, (3) examine the existence of the subadditivity bias and (4) test the impact of the underlying heterogeneity in preferences. Finally, we assessed several possible reasons invalidity of WTP estimates. WTP for a QALY was elicited in a representative sample of the general public in the Netherlands (n=1091). Analysis was performed both on between-sample and within-sample levels and different subsample levels, using parametric t-tests on log-transformed WTP estimates and non-parametric Mann-Whitney u-test. Our results showed little support for construct validity of WTP estimates both between and within samples, and on subgroup and average data level. Insensitivity to scale and subadditivity bias were confirmed. The study found that incremental increases in WTP were, overall, minimal and, therefore, theoretically implausible in comparison to the sizeable incremental increases in QALY gains. These results could not be explained by income constrains.Findings confirmed the hypothesis that WTP estimates do not comply with economic theory and are thus of questionable validity. We argue that the discrepancy between theory and empirical data could be caused by two general factors. First is the methodology itself, i.e. the properties of the QALY model, the relationship between WTP and QALYs and their scope. The second source of invalidity could be described as procedural issues that are outside of the realm of economic theory. An example is a framing effect. The paper suggests possible strategies for correcting or circumventing certain problems, both if they stem from methodological and procedural domains. Finally, the invalidity of WTP estimates implies that the currently obtained values may not be very useful. However, our view is that invalidity-related problems, although substantial, should not preclude us from using Contingent analysis in the search for the monetary cost-effectiveness threshold but should encourage more systematic work and commitment at improving the method of eliciting the WTP for a QALY.
    06/2010;
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    ABSTRACT: Changes in the health of patients may affect the health of so-called "significant others" in 2 distinct ways. First, an individual may provide informal care to the patient and be burdened by the process of care giving. We label this indirect effect of a patient's health on the health of the care giver the "care-giving effect." Second, a person may suffer from health losses because someone in his or her social environment is ill, regardless of his or her care-giving status. The health of the patient then directly affects the health of this significant other, which we label the "family effect." We investigate the occurrence of the family and care-giving effect in a convenience sample of Dutch care givers (n = 751). The family effect was approximated by the health status of the patient (measured on EuroQol-VAS), and the care-giving effect by the number of the care-giving tasks was provided. It was assumed that care givers' health is positively associated with patients' health, that is, the family effect, and negatively associated with care-giving burden, that is, the care-giving effect. Relationships are studied using multivariate regressions. Our results support the existence of both types of health effects. The analysis shows that the 2 effects are separable and independently associated with the health of care givers. Not accounting for the family effect conflates the care-giving effect. If the goal of health care policy is to optimize health, all important effects should be captured. The scope of economic evaluations should also include health effects in significant others. This study suggests that significant others include both care givers and broader groups of affected individuals, such as family members.
    Medical Decision Making 01/2010; 31(2):292-8. · 2.89 Impact Factor
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    ABSTRACT: The healthcare sector depends heavily on the informal care provided by families and friends of those who are ill. Informal caregivers may experience significant burden as well as health and well-being effects. Resource allocation decisions, in particular from a societal perspective, should account explicitly for these effects in the social environment of patients. This is not only important to make a complete welfare economic assessment of treatments, but also to ensure the lasting involvement of informal caregivers in the care-giving process. Measurement and valuation techniques for the costs and effects of informal care have been developed and their use is becoming more common. Decision-makers in healthcare - and eventually families and patients - would be helped by more uniformity in methods.
    Expert Review of Pharmacoeconomics & Outcomes Research 12/2008; 8(6):557-61. · 1.67 Impact Factor
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    ABSTRACT: Rationale: In 2005, the Institute of Public health in Primorsko-goranska County in Croatia introduced the Breast cancer screening program, encompassing all women aging 50-69 from the area. Decreasing participation rates (reaching only 55%) and unreliable source of funding have cast a shadow over future outcomes of the program. Objective: We aimed to elicit individual consumer preferences for breast cancer screening program options and propose strategies to assist decision makers in the area of improving participation rates. Individual willingness-to-pay (WTP) estimates may allow the program to be (partly) self financed. Methodology: We developed a discrete choice experiment (DCE). 70 respondents in the target group (women aging 50-69 from Primorsko-goranska County) filled in a paper-based questionnaire with 16 forced choices between two alternative programs. Following each choice, the respondents were given an "opt-out" option. The sample was made representative using inverse probability calibration weighting. Seven attributes described the program. Using mixed logistic regression we analysed the relative importance of these attributes and willingness to pay for each attribute. Furthermore, we defined a base program described by levels corresponding to actual breast cancer screening program in Primorsko-goranska County, and examined interventions for improving the uptake through the changes in levels subsequently affecting the predicted participation probability. Mixed logit was used to assess individual preference heterogeneity. Results: Respondents indicated that all attributes were relevant for their decision to participate in a screening programme. The attribute "sensitivity of the test" appeared most influential overall. Of the attributes that are amenable to policy change in the short-run, "welcoming manner at the screening point" seemed most prominent. Respondents were willing to pay a comparatively low amount to reduce travelling time to the point of the exam and a comparatively high amount for a higher sensitivity of the test. Variation in the attribute "cost" (with levels close to actual unit cost of the screening exam) had little relative impact on predicted participation rates, yet individual variation was significant. Willingness to pay to participate is generally higher than actual cost, indicating the possibility to self-finance the program. Variation in willingness can partly be explained by some background characteristics but is largely unexplained. Conclusion: Participation rates can be improved dramatically through enhancing test accuracy, which may be hard to alter in the short-run. Time waiting for results of the test and welcoming manner at the screening point, however, can be reduced and would also lead to an improvement of participation rates. The target group population is willing to pay substantial co-payments for participation, yet individual variation in willingness to pay was significant. While self-financing of the programme could be considered, it would have substantial equity consequences.