Trends in Incidence and Case Fatality Rates of Aneurysmal Subarachnoid Hemorrhage in Izumo City, Japan, Between 1980–1989 and 1990–1998

Abstract

Tetsuji Inagawa, MDBackground and Purpose-With aging of the population, the profile of subarachnoid hemorrhage (SAH) is likely to change; however, evaluation of long-term trends for incidence and case fatality rates of SAH is still limited. Methods-We compared the incidence and case fatality rates of aneurysmal SAH during the 9-year period 1990 -1998 with those during the 10-year period 1980 -1989 in Izumo City, Japan. Results- During 1980During -1989During and 1990During -1998, we diagnosed 170 and 188 patients as having aneurysmal SAH, respectively.The percentage of very elderly patients aged Ն80 years increased from 5% (8 patients) during 1980 -1989 to 18% (33 patients) during 1990 -1998 (PϽ0.001). The age-specific incidence rate of SAH has a tendency to increase with increasing age. The crude and the age-and sex-adjusted incidence rates using the 1995 population statistics for Japan were 21 and 23 per 100 000/y for all ages during 1980 -1989 and 25 and 23 per 100 000/y during 1990 -1998, respectively. The 3-month case fatality rate of patients aged Յ79 years decreased from 38% during 1980 to 26% during 1990, whereas the case fatality rates in patients aged Ն80 years were very high (63% and 79%, respectively) regardless of study periods. Consequently, the overall case fatality rates for patients with SAH were similar for the 2 study periods (39% and 36%). Conclusions-The age-and sex-adjusted incidence rates of aneurysmal SAH were stable over the 19-year period since 1980 and, despite improvement of outcome in patients aged Յ79 years, the overall case fatality rate was not lower because the improvements were counterbalanced by increasing numbers of very elderly patients. Key Words: cerebral aneurysm Ⅲ epidemiology Ⅲ incidence Ⅲ Japan Ⅲ subarachnoid hemorrhage J

Involvement of Meteorological Factors and Sex in the Occurrence of Subarachnoid Hemorrhage in Japan

“…SAH was thought to be due to aneurysm rupture in more than 97% of patients based on their medical history. The crude annual incidental rate of SAH in the present study was 18 per 100 000, which is similar to the previously reported annual age-and sex-adjusted incident rates of 23 and 15.5 per 100 000 in Japan, 10,25) so the patients in this study may be representative of the community population. Climate changes such as daily temperature, humidity, and atmospheric pressure have been proposed to influence seasonal patterns of SAH occurrence in previous studies.…”

Time trends in outcome of subarachnoid hemorrhage

“…Although SAH severity (distribution of WFNS grades at presentation) was comparable in OXVASC and OCSP (figure e-1), a greater proportion of patients surviving to reach hospital underwent vascular imaging in OXVASC compared to OCSP (24 [11][12][13][14][15][16], p ϭ 0.001). In OCSP, all 5 treated aneurysms were secured by surgical clipping, whereas in OXVASC, 15/18 (83%) treated aneurysms were secured by endovascular embolization.…”

“…13,14,16,[19][20][21]36 Data from the Perth Community Stroke Study from June 1995 to June 1996 19 were published separately from data from December 1996 to February 1998, 29 but these were combined for this analysis because the periods of study were so close. A pooled analysis of time trends within study populations, based on the difference in 1-month casefatality taken from the 2 furthest available timepoints (figure 2), demonstrated a 0.9% reduction in casefatality per annum (0.2-1.6, p ϭ 0.01).…”

Morphological and clinical risk factors for posterior communicating artery aneurysm rupture

“…Fourth, the observed differences may reflect racial differences in the patient population because recent genetic analyses indicated that Japanese and/or Finnish patients are at a higher risk of rupture. 17,25 Hence, the external validity applies only to a Japanese population and may not be generalizable to other ethnic groups. Finally, we performed 22 univariate analyses, with data presented in Tables 1 and 2.…”