Three worlds of health technology assessment: explaining patterns of diffusion of HTA agencies in Europe.

In the past two decades, setting up independent health technology assessment (HTA) agencies has become a popular tool to inform reimbursement decision-making in health care, spreading from Northern European countries across Western Europe but much less so to post-communist countries. Structural political science explanations leave gaps in clarifying this diffusion pattern. This paper proposes a theoretical model focusing on the influence of domestic epistemic communities mitigating policy diffusion. Based on a review of HTA institutions in the EU, it proposes a chronological taxonomy of HTA agencies in Europe (the forerunners, the mainstreamers and the non-adopters) and asks why there is such an important East-West divide. The paper discusses theoretical explanations from different literatures, finding unsatisfactory many traditional political science answers such as the degree of centralization of a country's health system, its financial organization (Bismarckian or Beveridgian), the attitude toward independent regulatory bodies in general, the influence of international actors, or lack of resources. Finally, it suggests cases for empirical testing of the domestic epistemic communities model.