STUDY OF ANEURYSMAL SUBARACHNOID HEMORRHAGE IN IZUMO CITY, JAPAN

Background and Purpose Estimation of the actual incidence rate of suba rachnoid hemorrhage and evaluation of the treatment require the inclus ion of all patients in a defined geographic area. Methods During 1987 through 1992 in Izumo City, Japan, we estimated the incidence rate of subarachnoid hemorrhage by including dead-on-arrival patients and by f urther adding the results obtained after reviewing all death certifica tes registered in this city in the corresponding period. In addition, we com pared the management and surgical outcomes in hospitalized pati ents from 1987 through 1992 with outcomes from 1980 through 1986. Resu lts During 1987 through 1992, we diagnosed 123 patients as having suba rachnoid hemorrhage. The crude and the age- and sex-adjusted incidence rates using the 1990 population statistics for Japan were 25 (95% con fidence interval, 21 to 30) per 100 000/y and 23 (95% confidence inter val, 19 to 28) per 100 000/y for all ages, respectively; these occurre nces are the highest among those reported to date. Of these patients, 8% died before receiving medical attention, 27% in the first week, and 39% at 1 month. The survival curve for 2 years improved significantly from 1980-1986 to 1987-1992 in patients with admission grades 4 and 5 (P=.035) and in operated patients with preoperative grades 1 through 3 (P=.036). However, there was little improvement in the overall manag ement results (P=.168), possibly because patients with high risk and/o r old age were admitted and/or diagnosed more often in the latter peri od. Conclusions The incidence rate of subarachnoid hemorrhage is much higher than that reported so far in the literature, and despite improv ement of management and surgical therapy, the actual case-fatality rat e is still high, mainly because of the high mortality rate directly as sociated with the primary bleeding.