Development of a value assessment framework for Health Technology Assessment in rare diseases drugs: insights from a Delphi study in Brazil

Objective The aim of this study is to propose and validate a value assessment framework for Health Technology Assessment (HTA) for rare diseases drugs in Brazil.Methods A scoping review was performed to identify criteria used by HTA agencies in countries with public healthcare systems when evaluating orphan drugs. Based on the findings, a criteria framework for rare disease drugs was proposed for Brazil. Content validity was conducted over three rounds using Delphi technique and content validity ratio (CVR) approach was employed to evaluate the ratings from the eighteen stakeholders (experts and patients).Results Twenty-nine HTA criteria for rare disease drugs were identified to compose the Brazilian framework. After three Delphi rounds, the final value framework comprised fifteen criteria categorized into four domains: disease-related factors, treatment-related factors, social and political factors, and economic factors. Among the most well-rated criteria by the CVR, considering the relevance attribute, were "relevance of outcomes for a rare disease," "impact on patient's quality of life," "price negotiation," and "adjusted cost-effectiveness threshold." On the other hand, "budget impact threshold," "innovative nature of treatment," and "willingness to accept greater uncertainty in clinical evidence" received negative evaluations and were excluded from the final framework.Conclusions A value assessment framework validated by key stakeholders of rare diseases in Brazil could contribute to improve HTA transparency, decision making, and efficiency of the healthcare system, and inspire the development of a local guidance for rare-disease HTA.