Feasibility of disease terminology systems for mapping orphan conditions and therapeutic indications of designated orphan medicines in the European Union

In the European Union, rare diseases are defined as diseases that affect maximum 5 in 10,000 citizens. These diseases are typically associated with a high unmet medical need. To stimulate development and authorisation of medicines for rare diseases ('orphan conditions'), the European Commission (EC) can grant orphan designations. In order to enable systematic evaluation and communication of the diseases for which designated orphan medicines have (not) been developed and authorised, we aimed to investigate the feasibility of important disease terminology systems for mapping orphan conditions and therapeutic indications.