OBJECTIVES: Health Technology Assessment (HTA) was introduced to the Japanese National Health Insurance (NHI) system in 2019. It was implemented not for coverage decision-making but for price revision in order to maintain the pre-existing rule of the Japanese NHI, covering almost all medications and avoiding delays to the initial pricing phase. We clarified issues with HTA in Japan from a methodological perspective.

METHODS: We reviewed Japanese HTA guidelines and actual HTA reports completed and published up to May 2022, discussing the issues involved.

RESULTS: Two issues of interest regarding Japanese HTA were observed. Firstly, the authorities' evaluations tend to set up more detailed/scattered subgroups, which may cause the reduction of statistical power. Maintaining additional/relative usefulness against comparator(s) might become very difficult, as evaluators still require statistical significance even with the scattered subgroups. Secondly, Japanese HTA guidelines suggest performing cost-minimization analysis (CMA) “if the additional benefit of the new technology is not demonstrated”, without providing any criteria for additional benefit. Using CMA with the absence of statistical significance, mainly due to lack of power, would not be an appropriate manner.

CONCLUSIONS: Japanese HTA was just introduced recently. Therefore, this is the time to identify more appropriate HTA practices aligned with Japanese healthcare and drug pricing systems within the government, academia, and industry (for instance, the HTA guidelines were revised in April 2022). The Japanese HTA system is expected to improve with further scientific discussion, including the points in this presentation.