Trends in the incidence of stroke and its subtypes from 1963 to 2018 in Japanese urban and rural communities: The Circulatory Risk in Communities Study (CIRCS)

Few studies have provided observational data on long-term trends in the incidence of stroke and its subtypes, and shown the urban-rural disparities of stroke incidence in Japan.A multiple-source, community-based stroke surveillance was performed since 1963/1964 to determine all first-ever stroke cases among Japanese residents aged ⩾40 years living in the Minami-Takayasu district in Yao city, an urban community, and Ikawa town, a rural community. Sex-specific, age-standardized incidence per 1000/year with 95% confidence intervals was calculated during seven periods of 1963/1964-1971 (urban population (% men): 3242 (47.3%); rural population (% men): 2311 (46.0%)), 1972-1979, 1980-1987, 1988-1995, 1996-2003, 2004-2011, and 2012-2018 (13,307 (46.7%); 3586 (44.8%)).The age-standardized incidence of all strokes in the Japanese urban community decreased from 6.60 to 1.15 per 1000/year for men and 3.28 to 0.59 for women. In the rural community, the corresponding incidence decreased from 11.51 to 1.98 for men and 6.46 to 1.31 for women. Similar reductions were observed in the incidence of intracerebral hemorrhage, subarachnoid hemorrhage, ischemic stroke, and lacunar stroke. In the period of 2012-2018, the incidence ratios (95% confidence intervals) of all strokes for the rural compared to the urban community were 1.72 (1.08-2.75) for men and 2.23 (1.23-4.03) for women.The stroke incidence continued to decline in both urban and rural Japanese communities with the regional disparities over the past half century, whereas it remained higher than that in many Western countries.