Elly A. Stolk

Dutch Tariff for the Five-Level Version of EQ-5D

BACKGROUND In 2009, a new version of the EuroQol five-dimensional questionnaire (EQ-5D) was introduced with five rather than three answer levels per dimension. This instrument is known as the EQ-5D-5L. To make the EQ-5D-5L suitable for use in economic evaluations, societal values need to be attached to all 3125 health states. OBJECTIVES To derive a Dutch tariff for the EQ-5D-5L. METHODS Health state values were elicited during face-to-face interviews in a general population sample stratified for age, sex, and education, using composite time trade-off (cTTO) and a discrete choice experiment (DCE). Data were modeled using ordinary least squares and tobit regression (for cTTO) and a multinomial conditional logit model (for DCE). Model performance was evaluated on the basis of internal consistency, parsimony, goodness of fit, handling of left-censored values, and theoretical considerations. RESULTS A representative sample (N = 1003) of the Dutch population participated in the valuation study. Data of 979 and 992 respondents were included in the analysis of the cTTO and the DCE, respectively. The cTTO data were left-censored at -1. The tobit model was considered the preferred model for the tariff on the basis of its handling of the censored nature of the data, which was confirmed through comparison with the DCE data. The predicted values for the EQ-5D-5L ranged from -0.446 to 1. CONCLUSIONS This study established a Dutch tariff for the EQ-5D-5L on the basis of cTTO. The values represent the preferences of the Dutch population. The tariff can be used to estimate the impact of health care interventions on quality of life, for example, in context of economic evaluations.

Reconciliation of economic concerns and health policy: Illustration of an equity adjustment procedure using proportional shortfall

Economic evaluations have become an important and much used tool in aiding decision makers in deciding on reimbursement or implementation of new healthcare technologies. Nevertheless, the impact of economic evaluations on reimbursement decisions has been modest; results of economic evaluations do not have a good record in predicting funding decisions. This is usually explained in terms of fairness; there is increasing awareness that valuations of QALYs may differ when the QALYs accrue to different patients. The problem, however, is that these equity concerns often remain implicit, and therefore frustrate explicitness and transparency in evidence-based decision making.It has been suggested that a so-called equity adjustment procedure may (partially) solve this problem. Typically this would involve the application of so-called equity weights, which can be used to recalculate the value of QALY gains for different patients. This paper explores such an equity adjustment procedure, using the equity concept of proportional shortfall.Proportional shortfall assumes that measurement of inequalities in health should concentrate on the fraction of QALYs that people lose relative to their remaining life expectancy, and not on the absolute number of QALYs lost or gained. It is the ratio of QALYs lost over the QALYs remaining. This equity concept combines elements of two popular but conflicting notions of equity: fair innings and severity-of-illness.We applied the concept of proportional shortfall to ten conditions and tentatively explored how an equity adjustment procedure using proportional shortfall might affect priority setting. Our equity adjustment procedure lowered the cost-effectiveness threshold when a condition was relatively mild. Because the proportional shortfall caused by the ten conditions differed considerably, the equity-adjustment procedure discriminated strongly between the ten conditions, and this experiment provided a good opportunity to explore the impact of equity adjustment for healthcare reimbursement decisions.In conclusion, our results suggest that equity can be measured and that integration of equity concerns into an economic evaluation improves the fit between economic models and reimbursement decisions. It is recommended that cost-effectiveness driven health policy systems consider equity adjustments.

Sample Size Requirements for Discrete-Choice Experiments in Healthcare: a Practical Guide

Discrete-choice experiments (DCEs) have become a commonly used instrument in health economics and patient-preference analysis, addressing a wide range of policy questions. An important question when setting up a DCE is the size of the sample needed to answer the research question of interest. Although theory exists as to the calculation of sample size requirements for stated choice data, it does not address the issue of minimum sample size requirements in terms of the statistical power of hypothesis tests on the estimated coefficients. The purpose of this paper is threefold: (1) to provide insight into whether and how researchers have dealt with sample size calculations for healthcare-related DCE studies; (2) to introduce and explain the required sample size for parameter estimates in DCEs; and (3) to provide a step-by-step guide for the calculation of the minimum sample size requirements for DCEs in health care.

Discrete choice modeling for the quantification of health states: The case of the EQ-5D

OBJECTIVES Probabilistic models have been developed to establish the relative merit of subjective phenomena by means of specific judgmental tasks involving discrete choices (DCs). The attractiveness of these DC models is that they are embedded in a strong theoretical measurement framework and are based on relatively simple judgmental tasks. The aim of our study was to determine whether the values derived from a DC experiment are comparable to those obtained using other valuation techniques, in particular the time trade-off (TTO). METHODS Two hundred nine students completed several tasks in which we collected DC, rank, visual analog scale, and TTO responses. DC data were also collected in a general population sample (N=444). The DC experiment was designed using a Bayesian approach, and involved 60 choices between two health states and a comparison of all health states to being dead. The DC data were analyzed using a conditional logit and a rank-ordered logit model, relying, respectively, on TTO values and the value for being dead to anchor the DC-derived values to the 0 to 1 quality-adjusted life-year (QALY) scale. RESULTS Although modeled DC data broadly replicated the pattern found in TTO responses, the DC consistently produced higher values. The two methods for anchoring DC-derived values on the QALY scale produced similar results. CONCLUSIONS On the basis of the high level of comparability between DC-derived values and TTO values, future valuation studies based on a combination of these two techniques may be considered. The results further suggest that DC can potentially be used as a substitute for TTO.

Quality of life instruments for economic evaluations in health and social care for older people: A systematic review

Gaining health may not be the main goal of healthcare services aimed at older people, which may (also) seek to improve wellbeing. This emphasizes the need of finding appropriate outcome measures for economic evaluation of such services, particularly in long-term care, capturing more than only health-related quality of life (HrQol). This review assesses the usefulness of HrQol and wellbeing instruments for economic evaluations specifically aimed at older people, focusing on generic and preference-based questionnaires measuring wellbeing in particular. We systematically searched six databases and extracted instruments used to assess HrQol and wellbeing outcomes. Instruments were compared based on their usefulness for economic evaluation of services aimed at older people (dimensions measured, availability of utility scores, extent of validation). We identified 487 articles using 34 generic instruments: 22 wellbeing (two of which were preference-based) and 11 HrQol instruments. While standard HrQol instruments measure physical, social and psychological dimensions, wellbeing instruments contain additional dimensions such as purpose in life and achievement, security, and freedom. We found four promising wellbeing instruments for inclusion in economic evaluation: Ferrans and Powers QLI and the WHO-Qol OLD, ICECAP-O and the ASCOT. Ferrans and Powers QLI and the WHO-Qol OLD are widely validated but lack preference-weights while for ICECAP-O and the ASCOT preference-weights are available, but are less widely validated. Until preference-weights are available for the first two instruments, the ICECAP-O and the ASCOT currently appear to be the most useful instruments for economic evaluations in services aimed at older people. Their limitations are that (1) health dimensions may be captured only partially and (2) the instruments require further validation. Therefore, we currently recommend using the ICECAP-O or the ASCOT alongside the EQ-5D or SF-6D when evaluating interventions aimed at older people.

Performance of the EuroQol in children with imperforate anus

Objective: To investigate the feasibility and validity of a proxy version of the EuroQol in children treated for imperforate anus. Methods: Patients included were between 1 and 51 years of age. Instruments included were the EuroQol, the TACQOL and a disease specific questionnaire, the Langemeijer Stool Questionnaire. Patients older than 15 years filled in all questionnaires themselves, in the age groups 5–10 and 11–15 a parent administered the questionnaires. Feasibility was judged on the number of missing values. In search of validity, EuroQol scores were compared with the prevalence of disease symptoms (convergent validity) and with the TACQOL (construct validity). Results: The number of missings was not related to age. The disease specific questionnaire correlated significantly with the EQvas from 11 years on and with the EQ-5Dindex from 5 years on. The mean correlation between contextual similar domains of the EuroQol and the TACQOL was −0.55. The correlation between different domains was −0.32. Conclusion: The results support the idea that the use of a proxy version of the EuroQol is feasible and valid. The convergent validity of the EQvas was supported from 11 years on. The EQ-5D showed good construct and convergent validity from 5 years on.

Balancing equity and efficiency in the Dutch basic benefits package using the principle of proportional shortfall

Economic evaluations are increasingly used to inform decisions regarding the allocation of scarce health care resources. To systematically incorporate societal preferences into these evaluations, quality-adjusted life year gains could be weighted according to some equity principle, the most suitable of which is a matter of frequent debate. While many countries still struggle with equity concerns for priority setting in health care, the Netherlands has reached a broad consensus to use the concept of proportional shortfall. Our study evaluates the concept and its support in the Dutch health care context. We discuss arguments in the Netherlands for using proportional shortfall and difficulties in transitioning from principle to practice. In doing so, we address universal issues leading to a systematic consideration of equity concerns for priority setting in health care. The article thus has relevance to all countries struggling with the formalization of equity concerns for priority setting.

Validity and feasibility of the use of condition-specific outcome measures in economic evaluation.

Background: Usually, generic questionnaires such as the EQ-5D or Health Utility Index (HUI) are used to obtain utility scores for computing QALYs. Sometimes, however, application of these instruments is not possible, or the responsiveness is doubted. An alternative strategy is to attribute utility scores to health states of a condition-specific outcomes measure (CSOM). We explored the validity and feasibility of this strategy. Research design: Our samples determined utility scores for the health states of the International Index of Erectile Function (IIEF) using time tradeoff (TTO). To reduce costs and time, the general population (n = 169) was interviewed in groups. We tested the validity of the group sessions in students. To test the extent of agreement between values obtained using the group and those obtained through individual administration, 63 students were interviewed individually and 54 in groups. Results: The utility scores for the disease-specific health states showed good construct validity. Also, the criterion validity of the adapted TTO was confirmed. Discussion: Disease-specific utility scores can be used in QALY analysis by converting them to a generic scale. Efforts should be undertaken to prevent response spreading. Administrating TTO in groups could reduce the time and costs of TTO administration and render the strategy of determining utilities for condition-specific health states more feasible.

Cost utility analysis of sildenafil compared with papaverine-phentolamine injections

Abstract Objective: To compare the cost effectiveness of sildenafil and papaverine-phentolamine injections for treating erectile dysfunction. Design: Cost utility analysis comparing treatment with sildenafil (allowing a switch to injection therapy)and treatment with papaverine-phentolamine (no switch allowed). Costs and effects were estimated from the societal perspective. Using time trade-off, a sample of the general public (n=169) valued health states relating to erectile dysfunction. These values were used to estimated health related quality of life by converting the clinical outcomes of a trial into quality adjusted life years (QALYs). Participants: 169 residents of Rotterdam. Main outcome measures: Cost per quality adjusted life year. Results: Participants thought that erectile dysfunction limits quality of life considerably: the mean utility gain attributable to sildenafil is 0.11. Overall, treatment with sildenafil gained more QALYs, but the total costs were higher. The incremental cost effectiveness ratiofor the introduction of sildenafil was £3639 in the first year and fell in following years. Doubling the frequency of use of sildenafil almost doubled the cost per additional QALY. Conclusions: Treatment with sildenafil is cost effective. When considering fundingsildenafil, healthcare systems should take into account that the frequency of use affects cost effectiveness.

Condition-Specific Preference-Based Measures: Benefit or Burden?

OBJECTIVES Some argue that generic preference-based measures (PBMs) are not sensitive to certain disease-specific improvements. To overcome this problem, new condition-specific PBMs (CS-PBMs) are being developed, but it is not yet clear how such measures compare with existing generic PBMs. METHOD We generated CS-PBMs from three condition-specific questionnaires (Health Assessment Questionnaire for arthritis, Quality of Life Questionnaire for Cancer 30 for cancer, and Multiple Sclerosis Impact Scale 29 for multiple sclerosis). First, the questionnaires were reduced in content, and then, a time trade-off study was conducted in the general public (N = 402) to obtain weights associated with the dimensions and levels of the new questionnaire. Finally, we compared utilities obtained by using the CS-PBMs with utilities obtained by using the EuroQol five-dimensional (EQ-5D) questionnaire in four data sets. RESULTS Utility values generated by the CS-PBMs were higher than those of the EQ-5D questionnaire. The Health Assessment Questionnaire-based measure for arthritis proved to be insensitive to comorbidities. Measures based on the Multiple Sclerosis Impact Scale 29 and the Quality of Life Questionnaire for Cancer 30 discriminated comorbidities and side effect equally well as the EQ-5D questionnaire and were more sensitive than the EQ-5D questionnaire for mild impairments. CONCLUSIONS The introduction of PBMs that are specific to a certain disease may have the merit of sensitivity to disease-specific effects of interventions. That gain, however, is traded off to the loss of comparability of utility values and, in some cases, insensitivity to side effects and comorbidity. The use of a CS-PBM for cost-utility analysis is warranted only under strict conditions.