HTA challenges for appraising rare disease interventions viewed through the lens of an institutional multidimensional value framework.

Evaluating rare disease interventions poses challenges for HTA agencies, including uncertainties and ethical issues and tensions. INESSS has recently adopted a Statement of Principles and Ethical Foundations which proposes a multidimensional approach to value appraisal as well as five principles to frame the evaluation process. Our aim was to identify and analyze HTA challenges for appraising interventions for rare diseases, using the Statement's approach to value appraisal as an analytical framework, and outline how the Statement's principles can help address these challenges. Challenges, covering a diversity of aspects, were identified by leveraging institutional experience in diverse domains of expertise and consolidated through narrative literature review. Challenges were categorized by value dimension (clinical, populational, economic, organizational, and sociocultural), which allowed to pinpoint how each challenge affects the ability to appraise the value of an intervention. Key ethical tensions across dimensions were also identified. Specific approaches to addressing these challenges - related to knowledge mobilization and integration, deliberation, and recommendation-making - were outlined on the basis of the principles promulgated in the A multidimensional approach can be fruitful for analyzing challenges for appraising the value of rare disease interventions and help guide approaches to tackle them.