Approximately 6,000–7,000 of the 30,000 known diseases could be defined as rare or orphan diseases with a prevalence threshold of around 40-50 cases per 100,000 people. Meaning the total global prevalence of rare disease is around 5%, or 400 million people worldwide. With over 30 million rare disease sufferers living in the EU and 25 million from the US.

Many rare diseases are caused by genetic mutations, hence a disproportionate number of patients are children suffering from hereditary diseases. However, certain infections and cancers can also be considered rare. There can be large geographic differences in prevalence across the globe. For example cystic fibrosis (CF) is very rare in Asia but has a prevalence of around 5 in 10,000 in Europe where some definitions wouldn’t class the disease as being rare.

Managing any rare diseases can be challenging for a number of reasons. Many physicians have little experience with them, which can result in protracted diagnostic pathways. Though in some cases, an increase in genetic testing and genome sequencing has sped-up diagnosis. Also, as total patient populations remain small, organising appropriate care is still difficult even when the underlying cause is found.

Hospitals tend to be reimbursed based on activity of routine procedures and specialty care units can often be underfunded as there are few incentives for hospitals to cater for the needs of these patients. Recently drives toward remote working and virtual clinics are helping to increase the reach of specialty units, treatment of rare disease often remains costly. In part because low prevalence means limited patients from which pharmaceutical companies can gain reimbursement for successful treatments

In 2018, an International Society for Pharmacoeconomics and Outcomes Research (ISPOR) Special Task Force Report identified and defined novel elements of value that have been under-examined within value assessment frameworks. Most of the components identified were relevant under a broader societal, rather than narrower health care perspective of valuation. These included the value of hope, which considers the impact of individual risk preferences on decision making. As well as scientific spillover, where new technology can help lead to more general innovation. Along with the impact of disease severity.

When defining the optimal focus of research into new treatments, a new study into societal perspectives of disease treatment from US citizens found many participants focused on the importance of factors such as equity, life expectancy, and young age at disease onset. This is consistent with the ideas of a ‘fair innings’, proposed in a classic paper by one of the early UK Health Economists, Alan Williams (1997). Believing everyone should have an equal chance at an equal lifespan of at least around 70 years. Such perspectives can be explored in more depth in relation to specific rare diseases through Discrete Choice Experiments (DCEs).

DCEs ask respondents to make a choice from two or more alternatives where at least one attribute is systematically varied and a series of choice tasks can elicit preferences. This method can be used to understand patient preferences across varying attributes and levels which are related to different treatment options. Quantifying this information is useful in helping support patient voice on emerging treatments.

Time Trade Off studies, (TTOs) also allows valuation of developed health states from the perspective of society as a whole, devoid of any bias that might derive from either having or providing care to person with a rare disease. Vignettes are used to paint a picture of what it would be like to live with a rare disease, before asking respondents to make trade off the time they would forgo living if it allowed them to live an improved state. Ultimately these methods allows researchers to generate societal preferences to support health care decision-making and generate additional QALY gains which would be associated with different outcome levels. Enhancing cost effectiveness arguments.

Expert elicitation can also be conducted to exploring market access issues and fill evidence gaps around rare disease. SHELF technique, the Sheffield Elicitation Framework, helps construct a probability distribution representing the views of experts regarding given parameters. Allowing researchers to gauge the level of consensus in areas of uncertainty when there is a paucity of evidence adds rigour and increases validity to the evaluation.

HCD Economics has already conducted preference research into haemophilia treatment regimes, as well as  elicitation of health state utilities associated with β thalassemia and Duchenne’s Muscular Dystrophy, DMD. For an informal chat about how preference research can support your market access and health economic strategies in rare disease, please contact: