Prevalence of stroke and stroke-related disability.

Prevalence of Stroke and Stroke-Related Disability To the Editor: Bonita and colleagues1 provide valuable information on the prevalence of stroke and the proportion with persisting sequelae. Their conclusions, drawn on the basis on an actuarial model, agree well with the results from a population-based survey from Nord-Trøndelag County, Norway.2 This study comprised 74 977 persons, including permanent nursing home residents; the attendance rate was 88.1%. The raw prevalence rate of stroke was 1850 per 100 000 in the population aged $20 years and 960 per 100 000 when standardized to the entire European population. However, when the sensitivity and specificity of the screening question3 are taken into account, one may have to adjust the prevalence estimate downward to approximately 1100 per 100 000.4 In the Table, age-specific prevalence estimates from the Nord-Trøndelag and the Auckland studies are compared. The Nord-Trøndelag study2 provides figures for self-reported motor impairments, whereas the Auckland study1 reports the prevalence rate of patients with self-reported incomplete recovery and those who need help in activities of daily living. The results of the two studies (for both sexes combined) are summarized in the Table. Despite focusing on different sequelae, the results are similar, especially in the older age groups. In the younger age groups, both studies have low numbers of events and thus less confident estimates. The credibility of such estimates increases when similar results are obtained by two different methods. The prevalence of stroke seems to be considerably higher than reported in older studies with more highly selected populations,5 and it increases from about 1% at age 50 to about 10% in the age group over 80 years. Approximately one in three of the younger patients and three in four of the older patients have persisting impairments and disabilities from the combined effect of stroke and other chronic diseases.6