Aki Tsuchiya

A review of studies mapping (or cross walking) non-preference based measures of health to generic preference-based measures

Clinical studies use a wide variety of health status measures to measure health related quality of life, many of which cannot be used in cost-effectiveness analysis using cost per quality adjusted life year (QALY). Mapping is one solution that is gaining popularity as it enables health state utility values to be predicted for use in cost per QALY analysis when no preference-based measure has been included in the study. This paper presents a systematic review of current practice in mapping between non-preference based measures and generic preference-based measures, addressing feasibility and validity, circumstances under which it should be considered and lessons for future mapping studies. This review found 30 studies reporting 119 different models. Performance of the mappings functions in terms of goodness-of-fit and prediction was variable and unable to be generalised across instruments. Where generic measures are not regarded as appropriate for a condition, mapping does not solve this problem. Most testing in the literature occurs at the individual level yet the main purpose of these functions is to predict mean values for subgroups of patients, hence more testing is required.

Orphan drugs and the NHS: should we value rarity?

The growing number and costs of drugs for rare diseases are straining healthcare budgets. Decisions on funding these treatments need to be made on a sound basis Cost effectiveness plays an important part in current decisions about the funding of health technologies. Drugs for rare disease (orphan drugs) are often expensive to produce and, by definition, will benefit only small numbers of patients. Several countries have put measures in place to safeguard research and development of orphan drugs, but few get close to meeting the cost effectiveness criteria for funding by healthcare providers. We examine the justifications for special status for rare diseases and ask whether the cost effectiveness of drugs for rare or very rare diseases should be treated differently from that of other drugs and interventions. The citizens council of the National Institute for Health and Clinical Excellence (NICE) was recently asked to consider whether the NHS should be prepared to pay premium prices for drugs to treat patients with very rare diseases.1 It recommended that the NHS should consider paying premium prices based on three criteria: the severity of the disease, evidence of health gain, and whether the disease is life threatening.1 The decision by the Department of Health to ring fence funding for enzyme replacement therapy for lysosomal disorders, with expected annual costs above £100 000 (

Using a discrete choice experiment to estimate health state utility values

180 000, €150 000) per patient for life, suggests that central government also currently believes that premium prices should be paid.2 NICE has conducted a feasibility study to explore whether its current processes and methods of technology appraisal can be applied to the appraisal of ultra-orphan drugs (those for diseases with a prevalence of 0.18/10 000 or less).3 It has not yet stated whether it will recommend that treatments for very rare diseases should have special …

Age-related preferences and age weighting health benefits

In this study we explored a novel application of the discrete choice experiment (DCE) that resembles the time trade off (TTO) task to estimate values on the health utility scale for the EQ-5D. The DCE was tested in a survey alongside the TTO in a sample of English-speaking Canadians recruited by a market research company. The study found that the DCE is able to derive logical and consistent values for health states valued on the full health - dead scale. The DCE overcame some issues identified in the version of TTO currently used to value EQ-5D, notably allowing for fewer data exclusions and incorporating values considered worse than dead without introducing a separate valuation procedure. This has important implications for providing robust values that represent the preferences of all respondents.

Canadian Valuation of EQ-5D Health States: Preliminary Value Set and Considerations for Future Valuation Studies

This paper deals with the relevance of age in the paradigm of quality adjusted life years (QALYs). The first section outlines two rationales for incorporating age weights into QALYs. One of them is based on efficiency concerns; and the other on equity concerns. Both of these are theoretical constructs. The main purpose of this paper is to examine the extent of published empirical support for such age weighting. The second section is a brief survey of nine empirical studies that elicited age-related preferences from the general public. Six of these quantified the strength of the preferences, and these are discussed in more detail in the third section. The analysis distinguishes three kinds of age-related preference: productivity ageism, utilitarian ageism and egalitarian ageism. The relationship between them and their relevance to the two different rationales for age weighting are then explored. It is concluded that, although there is strong prima facie evidence of public support for both types of age weighting, the empirical evidence to support any particular set of weights is at present weak.

Public healthcare resource allocation and the Rule of Rescue

Background The EQ-5D is a preference based instrument which provides a description of a respondents health status, and an empirically derived value for that health state often from a representative sample of the general population. It is commonly used to derive Quality Adjusted Life Year calculations (QALY) in economic evaluations. However, values for health states have been found to differ between countries. The objective of this study was to develop a set of values for the EQ-5D health states for use in Canada. Methods Values for 48 different EQ-5D health states were elicited using the Time Trade Off (TTO) via a web survey in English. A random effect model was fitted to the data to estimate values for all 243 health states of the EQ-5D. Various model specifications were explored. Comparisons with EQ-5D values from the UK and US were made. Sensitivity analysis explored different transformations of values worse than dead, and exclusion criteria of subjects. Results The final model was estimated from the values of 1145 subjects with socio-demographics broadly representative of Canadian general population with the exception of Quebec. This yielded a good fit with observed TTO values, with an overall R2 of 0.403 and a mean absolute error of 0.044. Conclusion A preference-weight algorithm for Canadian studies that include the EQ-5D is developed. The primary limitations regarded the representativeness of the final sample, given the language used (English only), the method of recruitment, and the difficulty in the task. Insights into potential issues for conducting valuation studies in countries as large and diverse as Canada are gained.

The QALY Model and Individual Preferences for Health States and Health Profiles over Time: A Systematic Review of the Literature

In healthcare, a tension sometimes arises between the injunction to do as much good as possible with scarce resources and the injunction to rescue identifiable individuals in immediate peril, regardless of cost (the “Rule of Rescue”). This tension can generate serious ethical and political difficulties for public policy makers faced with making explicit decisions about the public funding of controversial health technologies, such as costly new cancer drugs. In this paper we explore the appropriate role of the Rule of Rescue in public resource allocation decisions by health technology funding advisory bodies such as the National Institute for Health and Clinical Excellence. We consider practical approaches to operationalising the Rule of Rescue from Australia and the UK before examining the relevance of individual moral imperatives to public policy making. We conclude that that whilst public policy makers in a humane society should facilitate exceptional departures from a cost effectiveness norm in clinical decisions about identified individuals, it is not so obvious that they should, as a matter of national public policy, exempt any one group of unidentified individuals within society from the rules of opportunity cost at the expense of all others.

Estimating a Preference-Based Index for a 5-Dimensional Health State Classification for Asthma Derived from the Asthma Quality of Life Questionnaire

The numbers of quality-adjusted life years (QALYs) gained are increasingly being used to represent the gains in individual utility from treatment. This requires that the value of a health improvement to an individual is a simple product of gains in quality of life and length of life. The article reports on a systematic review of the literature on 2 issues: whether the value of a state is affected by how long the state lasts, and by states that come before or after it. It was found that individual preferences over health are influenced by the duration of health states and their sequence. However, although there is much variation across individual respondents, the assumptions tend to hold much better when valuations are aggregated across respondents, which is encouraging for economic evaluations that rely on using average (mean or median) values.

The first stage of developing preference-based measures: constructing a health-state classification using Rasch analysis.

Background: This article presents a valuation study to estimate a preference-based index for a 5-dimensional health state classification for asthma (AQL-5D) derived from the Asthma Quality of Life Questionnaire (AQLQ). Methods: A sample of 307 members of the UK general population valued 99 asthma health states selected from the AQL-5D using the time tradeoff technique. Models were estimated to predict all possible 3125 health states defined by the AQL-5D, and the models were compared in terms of their ability to predict mean values for the 99 states. Results: Mean health state values ranged from 0.39 to 0.94 based on an average of 22 valuations per state. A main effects model estimated on mean health state values and adjusted for consistency had the best predictive ability (mean absolute error of 0.047 and only 9/98 states with errors >0.1) and the most logical consistency with levels of the AQL-5D. The low number of valuations per state may have resulted in unreliable estimates for the models. Preference-based condition specific measures are limited in their ability to make cross-disease comparisons. Conclusion: This is the first study to derive a condition-specific preference-based measure from an existing measure of health-related quality of life in asthma for use in economic evaluation.

Using DCE and ranking data to estimate cardinal values for health states for deriving a preference‐based single index from the sexual quality of life questionnaire

ObjectiveTo set out the methodological process for using Rasch analysis alongside classical psychometric methods in the development of a health-state classification that is amenable to valuation.MethodsThe overactive bladder questionnaire is used to illustrate a five step process for deriving a reduced health-state classification from an existing non-preference-based health-related quality-of-life instrument. Step I uses factor analysis to establish instrument dimensions, step II excludes items that do not meet the initial validation process and step III uses criteria based on Rasch analysis and other psychometric testing to select the final items for the health-state classification. In step IV, item levels are examined and Rasch analysis is used to explore the possibility of reducing the number of item levels. Step V repeats steps I–IV on alternative data sets in order to validate the selection of items for the health-state classification.ResultsThe techniques described enable the construction of a five-dimension health-state classification, the OAB-5D, amenable to valuation tasks that will allow the derivation of preference weights.ConclusionsThe health-related quality of life of patients with conditions like overactive bladder can be valued and quality adjustment weights estimated for calculation of quality-adjusted life years.