Incidence of stroke in Frederiksberg, Denmark.

Since 1971, stroke registers in several countries have been cooperating in a study of stroke epidemiology, initiated by WHO. One of the registers covers the population of Frederiksberg, Copenhagen. During the first two years of registration strokes were recorded in 556 Frederiksberg citizens. A certain diagnosis of cerebral hemorrhage--verified by angiography, spinal fluid examination, or autopsy--was made in 10% of the patients; subarachnoid hemorrhage was demonstrated in only 2%; most of the remaining patients probably had cerebral infarction. The overall annual incidence of stroke, when adjusted for age for the Danish population, was 1.9 per 1,000 for males, and 1.6 per 1,000 for females. For every type of stroke, except subarachnoid hemorrhage, the incidence increased markedly with age. The age-specific stroke incidence rates found in the present investigation are much lower than those demonstrated by Aho in a community-based study in Finland. In view of the strict comparability of the two studies, real differences in the risk of stroke may exist between the two communities.