Fact-Finding Survey of Lethal or Fatal Adverse Drug Events in the Japanese Adverse Drug Event Report Database, Fiscal Year 2004–2023 (Adults ≥ 20 Years)

Background: While adverse drug events (ADEs) are a major public health concern, data on the occurrence of lethal or fatal ADEs in Japan are limited. Therefore, this study aimed to elucidate the characteristics and reporting trends of lethal or fatal ADEs by analyzing the Japanese Adverse Drug Event Report (JADER), a pharmacovigilance database. Methods: Of the individual ADE reports registered in the JADER database between April 2004 and March 2024 (fiscal year (FY) 2004–2023), all data involving individuals aged ≥ 20 years with complete data on sex and age were included in this analysis. Descriptive statistics were used to summarize the results. Results: The number of ADE cases registered in the JADER database increased approximately 2.3-fold from 21,824 in FY 2004 to 50,520 in FY 2023. Lethal or fatal ADE cases increased throughout the study period. In particular, the reporting rate of fatal ADEs reported in JADER appears to have increased in recent years. Lethal or fatal ADEs were reported more frequently among men and individuals aged ≥ 70 years. The recent increase in the reported rates of lethal or fatal ADEs may be largely influenced by the increased number of ADE reports associated with antineoplastic agents. The increase in the number of reports on immune checkpoint inhibitors is particularly notable. Conclusions: This study provides new insights into demographic and drug-related characteristics, as well as time trends associated with lethal or fatal ADEs in Japan. Further studies are needed to confirm these findings.