From a different angle: A novel approach to health valuation

The value of a health state is typically described relative to the value of an optimal state, specifically as a ratio ranging from unity (equal to optimal health) to negative infinity. Incorporating potentially infinite values is a challenging issue in the econometrics of health valuation. In this paper, we apply a directional statistics approach based on the assumption of wavering preference. Unlike ratio statistics, directional statistics are based on polar coordinates (angle, radius). The range of angles is bounded between 45 degrees (unity) and negative 90 degrees (i.e., negative infinity); therefore, mean angles are well behaved and negate the impetus behind arbitrary data manipulations. Using time trade-off (TTO) responses from the seminal Measurement and Valuation of Health study, we estimate 243 EQ-5D health state values by minimizing circular variance with and without radial weights. For states with published values greater than zero (i.e., better-than-death), the radially weighted estimates are nearly identical to the published values (Mean Absolute Difference 0.07; Lin’s rho 0.94). For worse-than-death states, the estimates are substantially lower than the published values (Mean Absolute Difference 0.186; Lin’s rho 0.576). For the worst EQ-5D state (33333), the published value is -0.59 and the directional estimate is -1.11. By taking a directional statistics approach, we circumvent problems inherent to ratio statistics and the systematic bias introduced by arbitrary data manipulations. The predictions suggest that published estimates overvalue severe states. This paper examines TTO responses; however, it may be extended to all forms of health valuation

Mix and match. A simulation study on the impact of mixed-Treatment comparison methods on health-economic outcomes

Background Decision-Analytic cost-effectiveness (CE) models combine many parameters, often obtained after meta-Analysis. Aim We compared different methods of mixed-Treatment comparison (MTC) to combine transition and event probabilities derived from several trials, especially with respect to health-economic (HE) outcomes like (quality adjusted) life years and costs. Methods Trials were drawn from a simulated reference population, comparing two of four fictitious interventions. The goal was to estimate the CE between two of these. The amount of heterogeneity between trials was varied in scenarios. Parameter estimates were combined using direct comparison, MTC methods proposed by Song and Puhan, and Bayesian generalized linear fixed effects (GLMFE) and random effects models (GLMRE). Parameters were entered into a Markov model. Parameters and HE outcomes were compare

A five-year model to assess the early cost-effectiveness of new diagnostic tests in the early diagnosis of rheumatoid arthritis

__Background:__ There is a lack of information about the sensitivity, specificity and costs new diagnostic tests should have to improve early diagnosis of rheumatoid arthritis (RA). Our objective was to explore the early cost-effectiveness of various new diagnostic test strategies in the workup of patients with inflammatory arthritis (IA) at risk of having RA. __Methods:__ A decision tree followed by a patient-level state transition model, using data from published literature, cohorts and trials, was used to evaluate diagnostic test strategies. Alternative tests were assessed as add-on to or replacement of the ACR/EULAR 2010 RA classification criteria for all patients and for intermediate-risk patients. Tests included B-cell gene expression (sensitivity 0.60, specificity 0.90, costs €150), MRI (sensitivity 0.90, specificity 0.60, costs €756), IL-6 serum level (sensitivity 0.70, specificity 0.53, costs €50) and genetic assay (sensitivity 0.40, specificity 0.85, costs €750). Patients with IA at risk of RA were followed for 5 years using a societal perspective. Guideline treatment was assumed using tight controlled treatment based on DAS28; if patients had a DAS28 >3.2 at 12 months or later patients could be eligible for starting biological drugs. The outcome was expressed in incremental cost-effectiveness ratios (€2014 per quality-adjusted life year (QALY) gained) and headroom. __Results:__ The B-cell test was the least expensive strategy when used as an add-on and as replacement in intermediate-risk patients, making it the dominant strategy, as it has better health outcomes and lower costs. As add-on for all patients, the B-cell test was also the most cost-effective test strategy. When using a willingness-to-pay threshold of €20,000 per QALY gained, the IL-6 and MRI

Quality Control Process for EQ-5D-5L Valuation Studies

Background: The values of the five-level EuroQol five-dimensional questionnaire (EQ-5D-5L) are elicited using composite time trade-off and discrete choice experiments. Unfortunately, data quality issues and interviewer effects were observed in the first few EQ-5D-5L valuation studies. To prevent these issues from occurring in later studies, the EuroQol Group established a cyclic quality control (QC) process. Objectives: To describe this QC process and show its impact on data quality. Methods: A newly developed QC tool provided information about protocol compliance, interviewer effects, and mean values by health state severity. In a cyclic process, this information is initially used to evaluate whether new interviewers meet minimal quality requirements and later to provide feedback about how their performance may be improved. To investigate the impact of this cyclic process, we compared the quality of the data in Dutch and Spanish valuation studies that did not have this QC process with that in the follow-up studies in the same countries that used the QC process. Data quality was measured using protocol violations, variability between interviewers, the proportion of inconsistent responders, and clustering of composite time trade-off values. Results: In Spain, protocol violations were reduced from 87% in the valuation study to 5% in the follow-up study and in the Netherlands from 20% to 8%. In both countries, interviewers performed more homogeneously in the follow-up studies. The number of inconsistent respondents was reduced by 23.2% in Spain and 23.6% in the Netherlands. Values were less clustered in the follow-up studies. Conclusions: The implementation of a strict QC process in EQ-5D-5L valuation studies increases interviewer protocol compliance and promotes data quality

Severity-Stratified Discrete Choice Experiment Designs for Health State Evaluations

__Background:__ Discrete choice experiments (DCEs) are increasingly used for health state valuations. However, the values derived from initial DCE studies vary widely. We hypothesize that these findings indicate the presence of unknown sources of bias that must be recognized and minimized. Against this background, we studied whether values derived from a DCE are sensitive to how well the DCE design spans the severity range. __Methods:__ We constructed an experiment involving three variants of DCE tasks for health state valuation: standard DCE, DCE-death, and DCE-duration. For each type of DCE, an experimental design was generated under two different conditions, enabling a comparison of health state values derived from current best practice Bayesian efficient DCE designs with values derived from ‘severity-stratified’ designs that control for coverage of the severity range in health state selection. About 3000 respondents participated in the study and were randomly assigned to one of the six study arms. __Results:__ Imposing the severity-stratified restriction had a large effect on health states sampled for the DCE-duration approach. The unstratified efficient design returned a skewed distribution of selected health states, and this introduced bias. The choice probability of bad health states was underestimated, and time trade-offs to avoid bad states were overestimated, resulting in too low values. Imposing the same restriction had limited effect in the DCE-death approach and standard DCE. __Conclusion:__ Variation in DCE-derived values can be partially explained by differences in how well selected health states spanned the severity range. Imposing a ‘severity stratification’ on DCE-duration designs is a validity requirement

Mathematical Approaches in Economic Evaluations: Applying techniques from different disciplines

Health economics (HE) is a multi-disciplinary field with links to economics, psychology and medicine. This is especially apparent in economic evaluations (EE) which have become an integral part in the management of health care systems in many western countries. In economic evaluations, information on a disease, on the cost of a treatment and on the effectiveness of the treatment is combined into a single mathematical model. This model is then used to assess the cost effectiveness of a treatment for the disease. The mathematical techniques employed to obtain and describe the information originate from three distinct mathematical disciplines associated with economics, psychology and medicine: econometrics, psychometrics and (bio)statistics. Even though there is a large amount of overlap, they all originated as separate disciplines and were developed with different perspectives in mind. This means that researchers in HE have a wide variety of different statistical and mathematical techniques at their disposal. This dissertation shows how ideas and approaches from different disciplines can be applied in solving health economic problems. Basic statistical techniques common to all fields, such as linear regression, are common. They are applied in most of the studies presented in this thesis. In addition to this, the studies described in this thesis show how more specialised techniques and approaches can be used outside the field where they were originally developed. In particular they are used in economic evaluations and the measurement and valuation of health related quality of life

The utilization of constitutional space to maximize sub-national autonomy in federations

Thesis (M.A.) University of Alaska Fairbanks, 2009"The comparative study of federal systems has most often focused on the view of federation 'from the top down.' This is particularly true of the study of constitutionalism in federations, in which federal constitutions have received significantly more attention than sub-national constitutions. An emerging concept in the understanding of federal systems from the sub-national perspective is the idea of constitutional space, which is defined as 'the range of discretion available to the component units in a federal system in designing their constitutional arrangements.' Some scholars have suggested that the full utilization of constitutional space can effectively increase the autonomy of sub-national units within a federation. This thesis explores the potential for increased sub-national autonomy through the utilization of constitutional space in a comparative analysis of state and provincial actions in the United States and Canada with regard to same-sex marriage and resource management, and concludes that due to the influence of additional factors in the federal relationship, the utilization of constitutional space by itself is insufficient to increase sub-national autonomy"--Leaf iii1. Introduction and overview of U.S. and Canadian Federalism -- Introduction -- Constitutional space defined -- Overview of U.S. and Canadian Federalism -- Origins of U.S. and Canadian Federalism -- Formation of the U.S. and Canadian federations -- Evolution of the U.S. and Canadian federations -- Conclusions on the origins, formation, and evolution of the U.S. and Canadian federal systems -- 2. Comparative federalism literature review -- Defining federalism/federation -- Federal vs. national governments -- Distinguishing between federation and confederation -- Origins of federations -- Motivations for forming federal systems -- Why federalism? -- Characteristics of federal systems -- Federalism, ethnic nationalism, and minority rights -- Symmetry vs. asymmetry in federations -- Distribution of power in federal systems -- Representation in federal systems -- Constitutional supremacy in federations -- The question of secession -- Suggestions for further research -- 3. Same-sex marriage and constitutional space -- Same-sex marriage in Canada -- Constitutional authority over marriage in Canada -- Provincial responses to demands for legalization of same-sex marriage -- The notwithstanding clause as a mechanism of provincial constitutional space -- Same-sex marriage in the United States -- The Romer decision and state responses -- Same-sex marriage and constitutional space in California -- Conclusions on the use of constitutional space in relation to conflicts over rights issues in Canada and the United States -- 4. State and provincial constitutional space in resource management -- Land ownership and resource management -- State vs. provincial constitutional arrangements -- Constitutional space and unwritten sub-national constitutions -- Constitutional space and written sub-national constitutions -- Provincial resource management in Canada -- The national energy program -- Impact of the resource amendment -- State resource management in the United States -- Use of the commerce clause to limit state constitutional space in the area of resource management -- State utilization of constitutional space in resource management -- Conclusions on resource management and the use of constitutional space in the United States and Canada -- 5. Conclusion -- Sub-national constitutional space and rights -- Sub-national constitutional space and resource management -- Implications for Alaska -- References

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

Abstract 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