10-YEAR TRENDS IN STROKE INCIDENCE AND MORTALITY IN THE FINMONICA STROKE STUDY

Background and Purpose The trends in stroke incidence reported so far have not been entirely consistent, although declining trends in mortal ity from stroke have been reported from a number of studies around the world. This study aims to evaluate the 10-year trends (from 1983 thro ugh 1992) in incidence, attack rate, and mortality of stroke in the Fi nnish population. Methods A population-based stroke register was set u p in the early 1980s to collect data on all suspected events of acute stroke that occurred in the population aged 25 to 74 years permanently residing in three geographic areas of Finland: the provinces of Kuopi o and North Karelia in eastern Finland and the Turku-Loimaa area in so uthwestern Finland. Trends in age-standardized attack rates, incidence , and mortality were calculated for the period studied. Results During the 10-year study period, 11 392 acute stroke events occurred in the monitored populations. A statistically significant decline was observe d in the pooled FINMONICA data, both in the incidence of stroke (-1.7% with 95% confidence interval [CI], -3.0% to -0.5% per year in men; -2 .2% with 95% CI, -3.6% to -0.7% per year in women) and in mortality fr om stroke (-5.2% with 95% CI, -8.2% to -2.2% per year; -4.7% with 95% CI, -8.2% to -1.2% per year). The attack rate of stroke also declined significantly in both sexes. When the areas were considered separately , the declining trends were observed within each area. The decline in incidence of stroke was, however, statistically significant only among men and women in Kuopio and among women in Turku/Loimaa. Mortality de clined significantly in all three areas among men but among women only in Kuopio. The incidence to mortality rate ratio increased during the study period, indicating a steeper fall in mortality than in incidenc e. Conclusions A substantial decline in both stroke incidence and mort ality was observed in the adult and elderly population in the FINMONIC A study areas. Part but not all of the decline in stroke mortality, ob served also in the official mortality statistics, can be attributed to the decline in stroke incidence during this 10-year period.