1. Cases of unnatural death during the course of 1990 were statistically investigated in six prefectures in terms of International Classification of Diseases-9 (ICD-9). The four prefectures, Tokyo, Kanagawa,Osaka and Hyogo, have medical examiner system (MES), whereas the other two, Shiga and Kagawa, have not.
2. The total cases investigated were 23833. Numbers and rates by causes of death were summarized as follows: 14042 (58.9%) disease cases, 143 (0.6%) accidental poisoning cases, 3575 (15.5%) other accidental cases, 4576 (19.2%) suicide cases, 238 (1.0%) homicide cases, 1144 (4.8%) unknown cases.
3. Out of the disease cases, 8549 (60.9%) and 5493 (39.1%) were recorded in the regions with MES and without MES, respectively.
4. When disease cases were classified by regions with and without MES, in the former regions, 69.4% were due to diseases of the circulatory systems, 9.4% to diseases of the digestive system, 8.3% to diseases of the respiratory system, and 12.9% to other diseases, wher
eas in the latter regions, the rates were 84.7%, 3.9%, 3.0%, and 8.5%, respectively.
5. The rates by detailed classification of diseases of the circulatory system in the regions with MES were estimated as follows: Ischemic heart diseases at 52.5%, "heart failure" at 10.2%, other heart diseases at 5.2%, subarachnoid hemorrhage at 4.3%, cerebral hemorrhage at 14.0%, other cerebro-vascular diseases at 3.5%, and other diseases of the circulatory system at 10.4%. On the other hand, those rates in the regions without MES were, 21.7%, 60.3%, 1.9%, 2.4%, 4.5%, 5.8%, and 3.4%, respectively.
6. Autopsy rates of the disease cases were estimated at 50.2% in the regions with MES and 1.9% in the regions without MES.
7. As mentioned above, the rates by organ system of deaths from diseases and those by detailed classification of deaths from the circulatory system showed remarked differences between the two regions. These findings indicate that medical examiner system is crucial in determining correct cause-of-death and in getting accurate cause-of-death statistics.
8. Strikingly higher rate of "heart failure" in the regions without MES seems to be ascribed not only to low autopsy rate of deaths from diseases but also to little recognition of the system of ICD-9 by doctors conducting a postmortem examination. The latter problem will have to be discussed in terms of medical education. Less