Clarifying and Proposing Solutions for Systemic Challenges in the Definition and Reporting of Indirect Disaster-Related Deaths in Japan

Introduction: Disaster risk reduction significantly reduced direct disaster-related deaths, but indirect deaths are becoming a significant issue after recent disasters in Japan, an aging society. Some of these deaths were officially certified for condolence grants to bereaved families who applied, which may hinder the accuracy of mortality statistics. This study aimed to investigate the extent to which official medical certificates documenting disaster relevance were included in the municipal documents for indirect disaster-related deaths. Methods: This study conducted a retrospective cross-sectional analysis using anonymized data obtained from municipalities through information disclosure (IRB approval: 2023-1-489). The study assessed 755 certified indirect disaster-related deaths after the 2011 Great East Japan Earthquake in the Miyagi Prefecture, Japan, to determine whether the medical documents in the certification included references to disaster relevance. Results: Of the 755 cases, 74 (9.8%) death certificates and 145 (19.2%) medical documents mentioned disaster relevance. In 536 (71.0%) cases, the disaster relevance was only mentioned in the self-reported documents submitted by bereaved families. The median interquartile range time from the disaster onset to disaster-related death was 21 days 7–52 days. The deaths occurred 61.1% within 30 days, 34.0% during 31-180 days, and 4.5% after 181 days. The mean age of the deceased was 79.7 years, with no gender difference. The predominant etiologies of these deaths included circulatory (32.7%) and respiratory (27.7%) diseases. Conclusion: Only 30% of official medical documents mentioned disaster relevance in 755 certified cases as indirect disaster-related deaths, suggesting the lack of systematic registration of disaster relevance. Especially, middle and long-term disaster-related deaths can be marginalized. After establishing social consensus, changing the medical practice and municipal handling of death certification for disaster-affected people is essential for accurate disaster mortality statistics.