Presentation (CTI)

OBJECTIVES: The Center for Outcomes Research and Economic Evaluation for Health (C2H) in Japan prioritizes the use of EQ-5D-5L utilities for health technology assessment (HTA) submissions, while allowing mapping when 5L data are unavailable. This study reviewed completed C2H HTA submissions to characterize mapping approaches and methodological gaps.
METHODS: Completed HTA submissions published by C2H between April 2019 and September 2025 were reviewed. Extracted data included whether mapping was employed to derive utilities, the source instruments, and the type of mapping algorithms applied. Use of Japan-specific tariffs and the complexity of mapping strategies were assessed. Additionally, C2H feedback and any subsequent re-analyses and decisions were evaluated.
RESULTS: Forty assessments were identified based on summary report dates, of which 9 (22.5%) relied on mapping. Of these, 4 originated from generic instruments and 6 from disease-specific instruments. Only one incorporated Japan-specific tariffs. Multiple levels of conversion were observed in several cases. In 6 cases, formal concerns were raised by C2H regarding the mapping methodology, leading to requests for additional or re-analysis. In many instances, documentation did not clearly describe how many conversions or the specific mapping algorithms used. This lack of transparency made it difficult to fully trace the derivation of utilities and to assess the validity and appropriateness of the selected mapping algorithms.
CONCLUSIONS: Mapping remains a common and often necessary solution, yet substantial methodological gaps persist. Reliance on multi-step conversions and non-local tariffs introduces uncertainty and complicates interpretation of cost-effectiveness estimates. While C2H has criticized the use of foreign tariffs, the absence of a clear alternative means this challenge persists, particularly given evidence that Japanese tariffs differ from UK or US tariffs. Future research should prioritize development of validated mapping algorithms using Japan-specific tariffs and establish standardized approaches for handling complex mapping pathways.