Mandy Ryan

Discrete choice experiments in health economics: a review of the literature.

Discrete choice experiments (DCEs) have become a commonly used instrument in health economics. This paper updates a review of published papers between 1990 and 2000 for the years 2001-2008. Based on this previous review, and a number of other key review papers, focus is given to three issues: experimental design; estimation procedures; and validity of responses. Consideration is also given to how DCEs are applied and reported. We identified 114 DCEs, covering a wide range of policy questions. Applications took place in a broader range of health-care systems, and there has been a move to incorporating fewer attributes, more choices and interview-based surveys. There has also been a shift towards statistically more efficient designs and flexible econometric models. The reporting of monetary values continues to be popular, the use of utility scores has not gained popularity, and there has been an increasing use of odds ratios and probabilities. The latter are likely to be useful at the policy level to investigate take-up and acceptability of new interventions. Incorporation of interactions terms in the design and analysis of DCEs, explanations of risk, tests of external validity and incorporation of DCE results into a decision-making framework remain important areas for future research.

Using discrete choice experiments to value health and health care

Using Discrete Choice Experiments to Value Health and Health Care takes a fresh and contemporay look at the growing interest in the development and application of discrete choice experiments (DCEs) within the field of health economics. The authors have written it with the purpose of giving the reader a better understanding of issues raised in the design and application of DCEs in health economics. The use of this relatively new instrument to value health and health care has now evolved to the point where a general text is necessary. The few existing books in this area are either research monographs or focus almost entirely on more advanced topics. By contrast, this book serves as a general reference for those applying the technique to health care for the first time as well as more experienced practitioners. Thus the book is relevant to post-graduate students and applied researchers with an interest in the use of DCEs for valuing health and health care and has international appeal. The book comprises Chapters by highly regarded academics with experience of applying DCEs in the area of health. The first part of the book summarises how DCEs can be implemented, from experimental design to data analysis and the interpretation of results. In many ways this can be regarded as a crash course on the conduct of DCEs. Extensive reference is made throughout to other sources of literature where the interested reader can find further details. The book also includes a series of case studies illustrating the breadth of applications in health economics and some key methodological issues. Finally there is an overview of research issues discussed which the editors believe are at the leading edge of this field.

USING CONJOINT ANALYSIS TO ASSESS WOMEN'S PREFERENCES FOR MISCARRIAGE MANAGEMENT

To date, standard gamble, time trade-off, visual analogue and, more recently, willingness to pay, have been most commonly employed in health economics to assess utilities from various health care interventions. This article considers the use of conjoint analysis as an alternative technique to assess utilities. The technique is applied to assess womens preferences for the management of miscarriage. The paper addresses methodological issues in the application of the technique to health care and demonstrates its use in estimating willingness to pay and utilities. It is concluded that conjoint analysis is potentially a very useful tool and that future research should investigate more thoroughly the potential application of the technique in health economics.

Using conjoint analysis to take account of patient preferences and go beyond health outcomes: an application to in vitro fertilisation.

There has been an assumption in the health economics literature that health outcomes are all that need to be considered when attempting to measure the benefits from health care interventions. This is most evident in the development of the quality adjusted life year (QALY) approach to benefit assessment. This paper challenges this view and considers the technique of conjoint analysis (CA) as a methodology for both taking account of patient preferences and considering attributes beyond health outcomes. The technique is applied to in vitro fertilisation. CA is shown to be sensitive to considering health outcomes, nonhealth outcomes and process attributes. It is also shown to be internally consistent and internally valid. The paper demonstrates the application of CA to estimating willingness to pay indirectly. It is argued that benefit assessment within health economics should extend beyond health outcomes and future research should investigate more thoroughly the potential application of CA in this area. However, methodological issues need addressing before the instrument becomes an established evaluative instrument.

Use of discrete choice experiments to elicit preferences

This paper considers the application of discrete choice experiments for eliciting preferences in the delivery of health care. Drawing upon the results from a recently completed systematic review, the paper summarises the application of this technique in health care. It then presents a case study applying the technique to rheumatology outpatient clinics. 200 patients were questioned about the importance of six attributes: staff seen (junior doctor or specialist nurse); time in waiting area; continuity of contact with same staff; provision of a phone-in/advice service; length of consultation; and change in pain levels. The systematic review indicated that discrete choice experiments have been applied to a wide number of areas and a number of methodological issues have been addressed. Consistent with this literature, the case study found evidence of both rationality and theoretical validity of responses. The approach was used to establish the relative importance of different attributes, how individuals trade between these attributes, and overall benefit scores for different clinic configurations. The value of attributes was estimated in terms of time, and this was converted to a monetary measure using the value of waiting time for public transport. Discrete choice experiments represent a potentially useful instrument for eliciting preferences. Future methodological work should explore issues related to the experimental design of the study, methods of data collection and analysis, and satisfaction with the economic axioms of the instrument. Collaborative work with psychologists and qualitative researchers will prove useful in this research agenda.

Methodological issues in the application of conjoint analysis in health care

This paper adds to an increasing literature on methodological questions addressed in the application of conjoint analysis (CA) in health care. Three issues are addressed: ordering effects; internal validity; and internal consistency. The results of an application of CA in a primary care setting provide no evidence that the ordering of scenarios was important. Evidence was found of both internal validity and internal consistency. In addition, individual preferences were found to be determined by experiences, which raise potentially important questions regarding the elicitation and use of such preferences in economic evaluation.

Comparing welfare estimates from payment card contingent valuation and discrete choice experiments.

This study presents the first comparison of willingness to pay estimates derived from the payment card (PC) contingent valuation and discrete choice experiment (DCE) methods. A within-sample experiment was used to elicit womens preferences for Chlamydia screening. The willingness to pay estimate derived from the DCE was larger than that derived from the PC. To investigate why the willingness to pay estimates were different, a range of validity tests were conducted. Both methods produced theoretically valid results, and there was no difference in the reported difficulty of completing the tasks. Evidence of a prominence effect was found in the PC responses. Responses to the DCE satisfied tests of non-satiation. Responses to both methods were compared with revealed preference data. There were significant differences between stated screening intention in both methods and actual screening uptake. Future work should address the external validity of stated preference methods.

Agency in health care: Getting beyond first principles

This paper is concerned with the application of the theory of agency to health care. It is argued that the basic theory of agency raises more questions than it provides answers when it is applied to the doctor-patient relationship. More research is needed into the nature of both the patients and the doctors utility functions. Only then can we begin to devise optimal incentive structures to encourage doctors to take adequate account of patient preferences.

Using discrete choice experiments to derive welfare estimates for the provision of elective surgery: Implications of discontinuous preferences

The estimation of a discrete choice experiment model complying with consumer theory axioms allows estimation of the welfare implications of alternative policies. Such a normative approach anchors the results of discrete choice experiments within a welfare economics framework. Where cost is included in the design, compensating variation can be estimated, permitting the use of the results directly within cost–benefit analysis. Any assumptions made about compliance with axioms however directly impact upon the welfare estimates derived from discrete choice experiments. Hence if discrete choice experiments are to be used to estimate welfare within health care, it is important that issues surrounding adherence to these axioms are explored. The study showed that a significant proportion of the sample did not comply with the axioms of continuity and transitivity, as defined by the specific tests used. This study compares welfare estimates obtained from continuous preferences with those which appear to be discontinuous. The results raise questions about how discrete choice experiment derived preferences should be incorporated into a traditional welfare economics framework.

Using discrete choice modelling in priority setting: an application to clinical service developments.

Limited resources for health care means that techniques are required to aid the process of priority setting. This paper represents one of the first attempts to use discrete choice modelling (DCM) within the area of priority setting. It is shown how the technique can be used to estimate cost per unit of benefit ratios for competing clinical service developments. Integer programming is proposed as a method to be used, alongside DCM, to help policy makers select the optimal combination of clinical service developments within a given budget. The technique is also shown to be internally valid and internally consistent. It is argued that DCM is a potentially useful technique to be used within the area of priority setting more generally. However, further work is required to address methodological issues around the technique.