Trend of stroke type in Japan based on the data of 150,899 stroke cases observed from 1984 to 2009 at all Rosai General Hospitals in Japan

Abstract

Background and Purpose: Though the mortality rate of stroke in Japan has decreased, the incidence rate has not decreased. But a large number of reports have been published on the changes of stroke type composition attributable to changes in life pattern. However, as the analytical data of a large scale longitudinal study group are limited and as many ambiguous points also exist in the stroke type diagnoses prior to the dissemination of CT, a study was conducted on the data of approximately 150,000 cases following the introduction of CT.Method: An analytical study was conducted on the changes of stroke type by sex and age of all the 150,899 stroke patients who were admitted and treated at all the 32 Rosai General Hospitals in Japan between 1984 and 2009.Results: The incidence of cerebral infarction increased annually until about 2003, but thereafter the incidence remained almost at a constant level, though cerebral hemorrhage continued to show a minimal increment. The incidence of subarachnoid hemorrhage remained almost constant. By disease type, cerebral infarction showed an increase from 54.6% to 66.2%, while cerebral hemorrhage showed a relative decrease from 28.7% to 26.2% and subarachnoid hemorrhage from 16.7% to 7.6%. In the study of the patients by age group, subarachnoid hemorrhage showed an increase in females of old age and cerebral hemorrhage an increase in both sexes in the old age group. With regard to cerebral infarction, cerebral thrombosis was high in males with increase in males in the 30s. Cerebral embolism showed little difference by sex, but increase was observed at advanced age.