How Is Evidence on Comparative Efficacy and Safety Presented in Japanese HTA Submissions: A Targeted Literature Review

OBJECTIVES: Japanese health technology assessment (HTA) was introduced in 2019 and guidelines for assessing comparative efficacy and safety were published in 2022, outlining recommended uses of indirect treatment comparisons (ITCs) and preferences over local versus global data. Currently, no study has systematically examined what methods have been used in practice and how these are perceived. This targeted literature review aimed to summarise approaches used in submissions since the inception of Japanese HTA.

METHODS: All company submissions submitted for Japanese HTA were reviewed. Data on what evidence were presented to demonstrate comparative effects were extracted, including methodological information on ITCs, where conducted, and whether trials included a Japanese population only, global population, or both. Feedback from the academic group relating to comparative evidence was summarised.

RESULTS: 27 HTA submissions since 2019 were identified, of which 14 had a public company submission available for review. Most submissions presented global clinical trials as their primary efficacy assessment, where some submissions reported results separately for global and Japanese trials and/or performed pooled trial analysis to increase power. ITCs were conducted in six submissions, with two submissions conducting a network meta-analysis, three submissions conducting a matching-adjusted indirect comparison, and one submission conducting a Bucher comparison. Some submissions conducted separate ITCs for global and Japanese populations. Feedback from the academic groups was mixed, with some criticisms of ITC assumptions and populations resulting in the academic groups conducting their own analyses in some cases.

CONCLUSIONS: Japanese HTA remains a relatively new process, and there exists heterogeneity in what comparative evidence is presented. Although a limited number of submissions conducted ITCs, the ITC methods used ranged in complexity and varied in whether data on Japanese populations was presented. Companies should consider also presenting evidence focusing on Japanese populations only when there exists heterogeneity between Japanese and global evidence.