Why do health technology assessment drug reimbursement recommendations differ between countries? A parallel convergent mixed methods study.

Using quantitative and qualitative research designs, respectively, two studies investigated why countries make different health technology assessment (HTA) drug reimbursement recommendations. Building on these, the objective of this study was to (a) develop a conceptual framework integrating the factors explaining these decisions, (b) explore their relationship and (c) assess if they are congruent, complementary or discrepant. A parallel convergent mixed methods design was used. Countries included in both previous studies were selected (England, Sweden, Scotland and France). A conceptual framework that integrated and organised the factors explaining the decisions from the two studies was developed. Relationships between factors were explored and illustrated through case studies. The framework distinguishes macro-level factors from micro-level ones. Only two of the factors common to both studies were congruent, while two others reached discrepant conclusions (stakeholder input and external review of the evidence processes). The remaining factors identified within one or both studies were complementary. Bringing together these findings contributed to generating a more complete picture of why countries make different HTA recommendations. Results were mostly complementary, explaining and enhancing each other. We conclude that differences often result from a combination of factors, with an important component relating to what occurs during the deliberative process.