The rarity of a disease can give rise to challenges that differ from conventional diseases. For example, rarity hampers research and development of new drugs, and patients with severe, rare diseases have limited access to qualified treatments. When drugs are available, clinical evidence has higher uncertainty and the drugs can be very expensive. When setting priorities in the healthcare sector, treatments aimed at patients with rare diseases, so called orphan drugs, have become a source of concern. Orphan drugs seldom show solid evidence of effectiveness or cost-effectiveness. Still, treatments for rare disease patients, available on the European market, has increased rapidly since the adoption of a regulation offering incentives for research and development of orphan drugs. The question arises as to whether the publicly funded health care system should provide such expensive treatments, and if so, to what extent.

This doctoral thesis aims to investigate healthcare priority setting and rare diseases in the context of orphan drug reimbursement. Priority setting for orphan drugs is located at the intersection of economic, ethical and psychological perspectives. This intersection is explored by studying the public’s view on the relevance of rarity when setting priorities for orphan drugs, and by examining how orphan drugs are managed when making reimbursement decisions in practice. Papers I and II in this thesis employ quantitative, experimental methods in order to investigate preferences for prioritising rare diseases, and the extent to which psychological factors influence such preferences. Papers III and IV employ qualitative methods to further explore what factors (apart from rarity) influence priority-setting decisions for orphan drugs, as well as how decisions regarding orphan drugs are made in practice in England, France, the Netherlands, Norway and Sweden. Combining quantitative and qualitative methods has provided a more comprehensive understanding of the topic explored in the thesis, and the methods have complemented each other.

Paper I shows that there is no general preference for giving higher priority to rare disease patients when allocating resources between rare and common disease patients. However, results show that preferences for treating the rare patients are malleable to a set of psychological factors, in particular “proportion dominance”. Paper II shows that the identifiability of an individual has no, or a negative, influence on the share of respondents choosing to allocate resources to him/her (compared to a nonidentified individual). Paper III confirms that rarity per se is not seen as a factor that should influence priority-setting decisions (i.e. accept a greater willingness to pay for orphan drugs), however, other factors such as disease severity, treatment effect and whether there are treatment alternatives were seen as relevant for consideration. Paper IV explores the challenges with and solutions for orphan drug reimbursement, as perceived by different actors in five European countries. Perceived challenges are related to the components involved when making reimbursement decisions, to the reimbursement system, and to the acceptance of the final decision. Solutions are either specific for orphan drugs, or general measures that can be used for orphan drugs as well as for other drugs.

In conclusion, priority setting for orphan drugs is complex and requires particular attention from decision makers. There are many factors to consider when making reimbursement decisions for orphan drugs. The consequences of a decision are potentially severe (both for rare disease patients and for common disease patients, depending on the decision) and psychological factors can potentially influence decisions.