Objectives: This review aims to provide an overview of the direction and magnitude of different factors impacting health technology assessments (HTAs) in healthcare.

Methods: Ovid Medline and Embase databases were searched for studies from inception to 2 July 2020. Studies were included if they conducted the multivariable analysis of HTA decisions. Meta-analysis was performed to investigate the impacts of factors on HTA decisions when the factors were investigated in at least a quarter of included agencies.

Results: Thirty-nine studies were identified including 7,696 decisions from fifteen HTA agencies. Eleven factors were investigated in more than 4 agencies and analyzed by meta-analysis further. Among them, three factors were identified as the significant factors for decision making in over half of investigated agencies: superior comparative efficacy and accepted clinical evidence as the positive factors, and high incremental cost-effectiveness ratio (ICER) as a negative factor. Seven factors were identified as significant factors by meta-analysis after pooling the decisions from the different agencies, where absence of alternatives, superior comparative efficacy, active comparator, high quality of clinical evidence and accepted clinical evidence were found as the positive factors, and oncology indication and high ICER were found as the negative factors.

Conclusions: Despite the different reimbursement systems, comparative efficacy, accepted clinical evidence and high incremental cost-effectiveness ratio are mostly identified to be important factors across the different agencies. The impacts of factors reflecting the equity principle, such as disease severity and orphan drugs, are limited especially in the agencies which emphasize the criterion of cost-effectiveness.

Keywords: Factor; health technology assessment; decision making; healthcare