[Subarachnoid hemorrhage in 'Vital Statistics of Japan', 1993-1995: variability with age and sex]

Abstract

The incidence and death rate of subarachnoid hemorrhage (SAH) varies with age and sex. Female preponderance in the incidence of SAH is a well-known fact. However, the degree varies with age. Autopsy data, records of natural history of unruptured aneurysms, epidemiological and clinical cooperative studies have provided a great amount of information regarding the statistics of subarachnoid hemorrhage. But, each individual study has its own limitation, such as a bias in case selection in autopsy or clinical studies, predominance of aged population in the epidemiological cohort studies, limited frequency in the detection of unruptured aneurysms in the entire population. These shortcomings are reflected in the variability in the statistical data of these studies. Death records in 'Vital Statistics of Japan', published annually by Ministry of Health and Welfare of Japan, exhibit the numbers of deaths by cause (according to ICD-9 or 10 code), sex and age. In this study, we calculated the death rates of SAH (per 100,000) in 1993-1995 for each age group of both sexes based on the published data. Deaths from breast cancers and automobile accidents (AMA) were assessed in the same manner and compared with the results of SAH. The annual death rate of SAH for all people in Japan is 10.7 per 100,000 population and the average age of death is 65.6 y.o. The death rate is 8.2 for men, and 13.1 for women. Average age at the death is 60.2 y.o. in men, and 68.8 y.o. in women (p < 0.001). The age-adjusted death rate to 1985 Japanese population was 7.3 for men and 9.2 for women. Below age 60, rate of death caused by SAH is higher for men than women, but the ratio reverses in the population over 60. For men, the death rates after the age of 40, 50, 60 and 70 were 16.4, 20.4, 24.1 and 29.2 respectively. For women, the rates were 25.0, 32.8, 44.1 and 62.4. The female-to-male ratio of the death rates increases with age. Female sex should be considered as a risk factor for death from SAH. Number of deaths from breast cancers was about 90% of those from SAH in women. There was a difference in the age distribution; deaths caused by breast cancer tend to occur in younger age than those caused by SAHs. Mean age of death was 59.3 for breast cancer and 68.8 for SAH. Deaths caused by SAH is 1.4 times more likely to occur than those by breast cancer for a 50 year-old woman for the rest of her life, 1.9 times for a 60 y.o. woman, and 2.7 times for a 70 y.o. woman. Regular examination to detect breast cancer is widely performed in Japan among elderly women. We believe that a similar screening effort should be targeted for unruptured aneurysms from the standpoint of the medico-social cost. Automobile accidents (AMA) victimize as many people as SAH in Japan, about 13,000 per year. For males over the age of forty, AMA victims are more than those from SAH. However, conversely females' deaths from SAH occur three times frequently as those from AMAs. The fact should be taken into consideration when screening for unruptured aneurysms.