OBJECTIVES: Until recently, cost-effectiveness evaluations (CEE) were largely unused in healthcare decision-making in Japan, despite annual medical expenditures reaching 40,000 billion JPY in 2013. Under the Central Social Insurance Medical Council, a new subcommittee on cost-effectiveness was formed. On a pilot basis in 2016, guidelines for developing CEEs were implemented and will be applied to future repricing of technologies every 2 years. Due to these recent changes, we systematically reviewed Japanese CEEs with a focus on methodology and data sources to help researchers build more useful models and provide decision makers with information to better interpret and use them.

METHODS: We searched MEDLINE, EMBASE, and J-STAGE (2013 through February 2018) for CEEs of adults in Japan. Included CEEs were full-text, full economic evaluations (both costs and effects were estimated) and compared one or more alternative interventions.

RESULTS: Of 3,444 studies identified, 32 CEEs were included. Eighty-eight percent were cost-utility analyses while 13% did not report quality-adjusted life years. The majority (69%) were published in clinical journals, whereas 22% were published in economic journals. Eighty-one percent used a Japanese healthcare system perspective, and all applied a 2-3% annual discount. A very limited number of CEEs used Japanese-specific preference-based instruments to determine health-related quality of life. Most data, no matter clinical, QALY, or costs, were sourced from the published literature or clinical trials. Only one CEE pooled clinical data to conduct a network meta-analysis to inform the clinical inputs.

CONCLUSIONS: Most of the published CEEs in Japan align with the new guidelines. A common deficiency included not conducting a literature review to identify appropriate inputs. Results of a CEE are only as valid as the data underlying it and based on our findings we feel that more guidance is needed surrounding selecting model inputs and methods reporting.