The implementation of health technologyassessment principles in public decisionsconcerning orphan drugs

PurposeOver the last few years, the share of public spending for orphan drugs (ODs) has increased in several western countries,raising concern on the exemptions granted to this sector with respect to the implementation of health technology assessment(HTA) principles. The aim of this paper is to shed light on both the HTA criteria adopted and the international agreementsimplemented in the OD regulation, given the new challenges imposed on western countries by a growing number of therapies forrare diseases.