The relationship between reliability and size of willingness-to-pay values: a qualitative insight

Factors affecting willingness to pay for NHS-based orthodontic treatment

Objective To assess factors affecting willingness to pay for orthodontic treatment.Methods An online discrete choice experiment and willingness to pay study was conducted on a convenience sample of 250 participants aged 16 and above over a four-month period. Participants completed a series of stated-preference tasks, in which they viewed choice sets with two orthodontic treatment options involving different combinations of attributes: family income; cost to patient; cause of problem; prevention of future problems; age; severity of the problem; and self-esteem/confidence.Results Family income, cost to patient, cause of the problem, age and self-esteem/confidence were the most important attributes influencing participants' decisions to have orthodontic treatment. Participants felt that free NHS-based orthodontic provision should be prioritised for those under 18, regardless of family income, for those with developmental anomalies, particularly where self-esteem and confidence are affected, with younger participants (aged 16-24 years) strongly preferring full NHS funding for those under 18 years old (p = 0.007, 95% CI: 0.57-0.09) who dislike smiling in public, especially where self-esteem and confidence are impaired (p = 0.002, 95% CI: 0.16-0.71). Participants with high annual income had the highest preference for the NHS to fund treatment regardless of income (p = 0.02, 95% CI: 0.13-1.47) and placed an onus on addressing developmental anomalies (p = 0.004, 95% CI: 0.22-1.15). In total, 159 (63.6%) of those who would undergo treatment were willing to pay for it, with the majority (88%) open to paying up to £2,000 and only three participants stating the NHS should not contribute towards the cost of orthodontic treatment.Conclusions Based on this pilot study, key factors influencing the decision to undergo treatment included family income, cost, the aetiology of malocclusion, age and self-esteem/confidence. It was felt that free NHS-based treatment should be given priority where self-esteem and confidence are impaired among young people. Further research to inform the priorities underpinning the provision of dental care and orthodontic treatment within the NHS is required.

Using willingness-to-pay to establish patient preferences for cancer testing in primary care

Background

Shared decision making is a stated aim of several healthcare systems. In the area of cancer, patients’ views have informed policy on screening and treatment but there is little information about their views on diagnostic testing in relation to symptom severity.

Methods

We used the technique of willingness-to-pay to determine public preferences around diagnostic testing for colorectal, lung, and pancreatic cancer in primary care in the UK. Participants were approached in general practice waiting rooms and asked to complete a two-stage electronic survey that described symptoms of cancer, the likelihood that the symptoms indicate cancer, and information about the appropriate diagnostic test. Part 1 asked for a binary response (yes/no) as to whether they would choose to have a test if it were offered. Part 2 elicited willingness-to-pay values of the tests using a payment scale followed by a bidding exercise, with the aim that these values would provide a strength of preference not detectable using the binary approach.

Results

A large majority of participants chose to be tested for all cancers, with only colonoscopy (colorectal cancer) demonstrating a risk gradient. In the willingness-to-pay exercise participants placed a lower value on an X-ray (lung cancer) than the tests for colorectal or pancreatic cancer and X-ray was the only test where risk was clearly related to the willingness-to-pay value.

Conclusion

Willingness-to-pay values did not enhance the binary responses in the way intended; participants appeared to be motivated differently when responding to the two parts of the questionnaire. More work is needed to understand how participants perceive risk in this context and how they respond to questions about willingness-to-pay. Qualitative methods could provide useful insights.

Contingent valuation: what needs to be done?

Contingent valuation (CV) has been argued to have theoretical advantages over other approaches for benefit valuation used by health economists. Yet, in reality, the technique appears not to have realised these advantages when applied to health-care issues, such that its influence in decision-making at national levels has been non-existent within the health sector. This is not a result of a lack of methodological work in the area, which has continued to flourish. Rather, it is a result of such activities being undertaken in a rather uncoordinated and unsystematic fashion, leading CV to be akin to a 'ship without a sail'. This paper utilises a systematic review of the CV literature in health to illustrate some important points concerning the conduct of CV studies, before providing a comment on what the remaining policy and research priorities are for the technique, and proposing a guideline for such studies. It is hoped that this will initiate some wider and rigorous debate on the future of the CV technique in order to make it seaworthy, give it direction and provide the right momentum.

Qualitative methodologies in health-care priority setting research

Priority setting research in health economics has traditionally employed quantitative methodologies and been informed by post-positivist philosophical assumptions about the world and the nature of knowledge. These approaches have been rewarded with well-developed and validated tools. However, it is now commonly noted that there has been limited uptake of economic analysis into actual priority setting and resource allocation decisions made by health-care systems. There seem to be substantial organizational and political barriers. The authors argue in this paper that understanding and addressing these barriers will depend upon the application of qualitative research methodologies. Some efforts in this direction have been attempted; however these are theoretically under-developed and seldom rooted in any of the established qualitative research traditions. Two such approaches - narrative inquiry and discourse analysis - are highlighted here. These are illustrated with examples drawn from a real-world priority setting study. The examples demonstrate how such conceptually powerful qualitative traditions produce distinctive findings that offer unique insight into organizational contexts and decision-maker behavior. We argue that such investigations offer untapped benefits for the study of organizational priority setting and thus should be pursued more frequently by the health economics research community.

Subject variation more than values clarification explains the reliability of willingness to pay estimates

In a recent article in this journal, Smith offers additional evidence to support his claim that the test-retest reliability of willingness to pay measures increases along with willingness to pay because people take more time to consider their answers for the more highly valued (and therefore more 'expensive') goods. Unfortunately, by repeating a common misconception about what reliability actually measures, he overlooks an alternative explanation for the relationship he observed; namely, that subject variation increases with willingness to pay and that it is this, rather than any reduction in measurement error, that explains his findings. We show that 75% of the increase in reliability comes from increases in subject variation (that is different views about the value of good health), and that the relationship between measurement error and willingness to pay is not as simple as Smith suggests. However, our critique of Smith's paper should not be construed as criticism of the ideas being explored. We need to better understand the responses people give to contingent valuation exercises. Such understanding has to be based on a better appreciation of what reliability is and on more robust testing of alternative hypotheses.