Concepts, methods, and outcomes in the evaluation of diagnostic and therapeutic technologies for ultra-rare diseases: a systematic scoping review

Ultra-rare diseases (URDs) are typically chronic, progressive, and life-threatening, characterized by very low prevalence and a high burden on patients and health systems. This systematic scoping review provides an overview of the concepts, methodological approaches, and outcome measures currently used to evaluate diagnostic and therapeutic technologies for URDs in countries where English, Portuguese and Spanish are official languages.