DECLINING TRENDS IN INCIDENCE, CASE-FATALITY AND MORTALITY OF STROKE IN 3 GEOGRAPHIC AREAS OF FINLAND DURING 1983-1989 - RESULTS FROM THE FINMONICA STROKE REGISTER

Stroke mortality has decreased during the last decade in many industri alized countries, but there has been no clear evidence for a decline i n the incidence of stroke. The present study analyzes the trends in th e incidence, mortality and case-fatality of stroke in Finland from 198 3 to 1989. We used data from the FINMONICA stroke register, a communit y based register collecting information on all suspected stroke cases aged 25-74 in three geographical areas of Finland. Annual attack rate, incidence, mortality and case-fatality rates were calculated for all strokes and for different subcategories of stroke. A linear regression model was applied to calculate the yearly trends of these rates. In m en, the attack rate of stroke was 336/100,000 in 1983 and 310/100,000 in 1989 (-8% during the observation period); incidence declined from 2 69/100,000 in 1983 to 236/100,000 in 1989(-12%); mortality declined fr om 82/100,000 to 64/100,000 (-22%), and case-fatality declined from 25 % to 21% (-18%). Also among women similar declining trends were observ ed (-11%, -13%, -16%, and -10% respectively), but they were not statis tically significant. In both incidence and mortality of stroke, the de cline was seen in all age groups. Incidence and mortality of cerebral infarction declined similarly to all strokes. A large fall in the inci dence (-24% in both men and women) and mortality (-38% in men and -27% in women) of subarachnoid haemorrhage was also observed. An increasin g trend, although not significant, was instead observed for cerebral h aemorrhage. First stroke and especially first cerebral infarction cont ributed most to the decline in case-fatality. The availability of comp uterized brain tomography improved from 18% in 1983 to 60% in 1989. We observed a fall in the incidence, mortality, and case-fatality of str oke during 1983-1989. Among the subtypes of stroke, cerebral infarctio n contributed most to the decline, but the data suggested also a decli ning trend in the incidence and mortality of subarachnoid haemorrhage, observed now for the first time in Finland since the 1960s. The fall in the incidence of stroke was not as steep during the 1980s as it was during the 1970s; Finland is anyhow the only European country which h as reported a decreasing trend in stroke incidence during the 1980s. W e need now to investigate how much the decline in the classical risk f actors for stroke observed in Finland during the last two decades pred icts the observed trends.