The 21-Year Trend of Stroke Incidence in a General Japanese Population: Results from the Takashima Stroke Registry, 1990-2010.

Introduction: Since the 1960s, the stroke morality rate in Japan has declined significantly. Although several risk factors for stroke have become more evident due to increasingly Westernized lifestyle, there have been no population-based registry data on recent time trends in stroke incidence in Japan. The purpose of this study is to determine these trends in stroke incidence using a population-based registry.

Methods: Data were obtained from the Takashima Stroke Registry, which covers approximately 50,000 residents in Takashima City, Japan. The age- and sex-standardized stroke incidence rate was estimated using the direct method. Average annual relative changes of stroke incidence were estimated using Poisson regression models.

Results: We identified a total of 2,371 patients with first-ever stroke during the period 1990-2010. Crude incidence rates of total stroke (per 100,000 person-years) were 225 in the early period (1990-2001) and 187 in the late period (2002-2010), and the mean age at onset of stroke increased from 71.9 years in the early period to 74.8 years in the late period. Age- and sex-standardized incidence rates of stroke (per 100,000 person-years) decreased from 327 in the early part of this study period and 206 in the later period. During the 21-year period, age- and sex-standardized average annual relative reduction in stroke incidence was statistically significant (-3.7% per year). When stratified into early and late periods, the adjusted annual relative reduction in stroke incidence was observed during the early period (-2.1% per year), and there were no significant changes during the late period.

Conclusions: In this population-based registry, there was a significant reduction in incidence of stroke from 1990 to 2010. Although the speed of reduction in stroke incidence appears to have slowed down after 2000, continuous public health measures are required to provide further protection against stroke.