Increased acute myocardial infarction mortality following the 1995 Great Hanshin-Awaji earthquake in Japan

Background This study examined the factors affecting mortality from acute myocardial infarction (AMI) following the 1995 Great Hanshin-Awaji earthquake. Methods We examined the death certificates of all decedents between January 1994 and December 1996 in 16 municipalities, which covered most of the area affected by the 1995 Great Hanshin-Awaji earthquake. We analysed the extent and duration of the increased mortality from AMI. The standardized mortality ratio (SMR) of AMI was calculated weekly after the earthquake, taking the number of AMI deaths during the same period in 1994 as a reference. The main outcome measures were the number of deaths from AMI (ICD-9 410; ICD-10 121, 122) in the study area before and after the earthquake, and the weekly SMR after the earthquake. Results A significant increase in mortality from AMI in the study area as a whole continued for about 8 weeks after the earthquake. There was wide variation amongst the regions with respect to the extent and duration of the increased mortality from AMI. The SMR of AMI showed a positive relationship with the percentage of houses which were completely destroyed, and was almost significant (r = 0.530, P = 0.062). Conclusions The duration of increased cardiac mortality after the 1995 Great Hanshin-Awaji earthquake was longer than seen with previous earthquakes. Further analysis to identify the factors affecting cardiac mortality is needed so that we may reduce adverse health effects during the recovery stage following natural disaster.