Decreasing incidence of stroke in central Finland, 1985-1993

During the last decades the age-standardized stroke mortality has declined in Finland as in many other industrialized countries. Epidemiological studies have, however, not been consistent in explaining this fall in mortality. Our aim was to shed light on this question by using two consecutive, population-based surveys.

The target of the two one-year surveys was the population living in the Jyväskylä Region of central Finland, and the surveys were performed in 1985-86 (population 114,669) and 1993 (population 123,547). The case finding methods and the diagnostic criteria were identical in both studies. All hospital records and autopsy reports of patients with ICD (8th and 9th revision) codes 430-438 were collected and perused. Patients with first-ever stroke were included in the study.

The number of patients with first-ever stroke in the 1985-86 and 1993 surveys were 219 and 189, respectively, and 92% of them were treated at the Department of Neurology. The age-standardized (European standard population > or = 25 years) annual total stroke incidence showed a statistically significant decline over these 8 years from 317 (95% confidence interval 274-360) to 227 (95% confidence interval 194-260) per 100,000. In both studies the survival was similar with 79% of the patients surviving at 28 days after stroke onset, and 65-69% at 1 year. Recurrent strokes, 52 in 1985-86 and 50 in 1993 also showed a declining trend and no changes in survival were observed.

The decline in stroke mortality in Finland is best explained by the declining incidence of stroke. In the present study we did not find changes in the 1st year survival after stroke onset.