Incidence and early prognosis of aneurysmal subarachnoid hemorrhage in Kumamoto Prefecture, Japan

OBJECTIVE: We analyzed the community incidence and early prognosis of first-ever aneurysmal subarachnoid hemorrhages (SAHs) to obtain the same prognostic information used by physicians and families in a defined geographic area in Japan. METHODS: During the 5-year period from January 1, 1996, to December 31, 2000, 2115 patients were registered in the Data Bank for Cerebral Aneurysms of Kumamoto Prefecture, a defined area in Japan with a population of 1.86 million. Registration was based on a comprehensive referral system for SAH patients; computed tomographic scans were available for all patients, including those who were moribund or dead on arrival. We compared the treatment outcomes at 3 months after the first-ever SAH in surgically and conservatively treated patients. RESULTS: The age-adjusted annual incidence of SAH for men, women, and both sexes was 15.9, 26.6, and 21.6 per 100,000 person-years, respectively. In men, the incidence reached a plateau after age 40 years. In women, conversely, it rose after age 40 and peaked in the 9th decade of life. Of the 1634 surgically treated patients, 1153 (70.6%) had a favorable outcome; this was true for only 27 of 477 (5.7%) conservatively treated patients. Four patients were lost to follow-up. The clinical outcome did not differ between patients treated by open surgery and those treated endovascularly. Approximately 30% of our patients were older than 70 years at the time they experienced their first SAH. CONCLUSION: The incidence of SAH obtained in this study was similar to earlier Japanese reports and Finnish studies. The importance of managing elderly patients with cerebral aneurysms will continue to increase.