Trends in stroke incidence and 10-year survival in Soderhamn, Sweden, 1975-2001

Background and Purpose - Stroke mortality rates have declined in many countries. Stroke incidence rates have also declined, but not to the same extent and not always in parallel with stroke mortality. The aim of the present study was to investigate trends in stroke incidence and long-term survival in a Swedish population. Methods - A population-based survey of the incidence of first-ever stroke was performed prospectively in the periods 1975 to 1977, 1983 to 1986, and 1987 to 1990. Case fatality ratios and survival rates were followed to 2001. Results - Crude incidence rates increased between 1975 to 1977 and 1983 to 1986, but age- and sex-adjusted incidence rates were stable during the whole period of 1975 to 1990. The incidence of intracerebral hemorrhage decreased by approximately two thirds, whereas the incidence of mild brain infarction almost doubled. The case fatality ratio at 28 days did not change, but the 10-year survival ratio increased from 13% to 35%. Mean survival time increased significantly among patients with intracerebral hemorrhage and brain infarction but not among patients with subarachnoidal hemorrhage or stroke of undetermined origin. Conclusions - Stroke incidence and short-term case fatality did not change between 1975 and 1990 in the Soderhamn population. Long-term survival after stroke, on the other hand, has continued to improve to 2001. The implication of these changes is that the burden of stroke is likely to increase unless strokes are becoming less severe.