Incidence Rate of Cerebrovascular Diseases in Northern Japan Determined from the Iwate Stroke Registry with an Inventory Survey System

Background: Long-term stroke registries in large populations often fail to maintain accuracy. This study presents an inventory survey system for stroke registries and the incidence rate of cerebrovascular diseases in a region with the highest stroke mortality rate in Japan. Methods: Using the data of the stroke registry determined with the inventory survey from 2004 to 2008 in northern Iwate Prefecture, with a population of 235,280 (111,584 men and 123,696 women), the age-specific annual incidence rates, the age-adjusted annual incidence rates, and the ratio of incidence rate relative to mortality rate of the cerebrovascular diseases were investigated. Results: A total of 3415 cases (1714 men and 1701 women) were registered and analyzed in this study. The age-adjusted incidence rates by the 1985 model population of Japan and by the world standard population (range 35-64 years) were 100.4 and 89.4 per 100,000 population in men and 49.8 and 29.7 in women for cerebral infarction; 53.6 and 77.2 in men and 34.2 and 39.5 in women for intracerebral hemorrhage; 12.9 and 23.3 in men and 21.1 and 34.6 in women for subarachnoid hemorrhage; and 166.9 and 189.8 in men and 105.0 and 103.7 in women for all subtypes. The ratios of incidence rate relative to mortality rate were 1.66 for all stroke subtypes, 1.69 for cerebral infarction, 1.76 for intracerebral hemorrhage, and 1.31 for subarachnoid hemorrhage. Conclusions: High incidence rates of cerebrovascular diseases were revealed in the stroke registry with a good inventory survey in northern Iwate Prefecture, Japan.