Trends in stroke incidence and acute case fatality in a Japanese rural area - The Oyabe study

Background and Purpose-Stroke mortality in Japan has significantly declined during recent decades. To determine the cause of this decrease, we studied the trends in stroke incidence and case fatality within 28 days after stro ke in a rural area in Japan. Methods-We used a population-based registry during 1977-1991 in Oyabe, a ru ral area in the central part of Japan. The average population aged 25 years and older numbered 32 859 persons. Changes in age-standardized stroke inci dence rate were calculated and compared between the 3 periods 1977-1981, 19 82-1986, and 1987-1991, The 28-day case fatality rate was evaluated and als o compared between the 3 periods by onset year. Results-The total number of strokes was 2068. The age-standardized incidenc e rate of all strokes decreased during the 15-year period, from 605 to 417 per 100 000 in men and from 476 to 329 per 100 000 in women. A marked decli ne was found during 1977-1986 but was not apparent during 1987-1991. Moreov er, there was an-increase in the group aged 75 years and older. The 28-day case fatality rates for all strokes improved from 18.0% to 14.2% in men and from 26.8% to 19.1% in women during the observation period. Conclusions-These data indicate that declines in the stroke incidence and t he 28- day case fatality have been associated with a marked decrease in str oke-related mortality in Japan.