Incidence of cerebral hemorrhage in the Changsha community. A prospective study from 1986 to 2000

Background and purpose: Intracranial hemorrhage (ICH) constitutes an important subtype of stroke. In a prior study, we found that the city of Changsha, People's Republic of China, not only had a high incidence of stroke, but also had almost the highest incidence of cerebral hemorrhage. To provide information for preventing and managing ICH, we undertook this study supervising and determining the annual first-ever average incidence of cerebral hemorrhage from 1986 to 2000 in Changsha.

Methods: In January 1986, people from 6 well-defined communes in the Kai-fu district in Changsha were selected as the study population. Since 1991, we added another 18 well-defined communes of the same district. Data on these residents were obtained from the census register of the local administrative office. Persons who had a history of stroke were excluded from our study at the beginning. Every year, we checked up on the population and carried out door-to-door inquiries to verify the new cases of ICH and stroke. If the patients were diagnosed in hospital, as many as possible were examined with CT and/or MRI. The incidence rate adjusted to the World population in 1985 for age and sex, as well as the prevalence of risk factors were calculated.

Results: An accumulative total of 551,163 people were supervised in 15 years (from 1986 to 2000); the annual average incidences of stroke and ICH were 236.6/100,000 (adjusted rate: 154.7) and 131.0/100,000 (adjusted rate: 73.1), respectively. From 1986 to 2000, the total annual average rate of stroke confirmed by CT and/or MRI in Changsha was 70.8%, and for ICH it was 64.7%. The incidences of stroke and ICH confirmed by image analysis were 167.5 (adjusted rate: 110.8) and 84.7 (adjusted rate: 55.1), respectively. The mean annual mortality rate of ICH was 78.3/100,000 (adjusted rate: 49.3) and that of stroke was 124.5/100,000 (adjusted rate: 97.0). The percentage of ICH among stroke cases was 55.4%. Among patients with ICH, 79.8% had hypertension, 30.6% had cardiovascular disease, 7.6% had diabetes mellitus, and 12.5% had an abnormal high level of lipid. Among patients with other subtypes of stroke apart from ICH, the percentages were 76.6, 40.6, 15.5, and 22.5%.

Conclusions: The incidence of ICH in Changsha is very high, so is the proportion of ICH among all stroke cases. Changsha is an area with a high incidence of ICH in the world. Hypertension is the prominent risk factor. The study demonstrated the importance of ICH as a significant subtype of stroke.