Proportion of older people in the community as a predictor of increasing stroke incidence

Objectives: To compare stroke incidence rates among comparable registries a nd to make correlations with aging of the resident populations. Methods: Th is correlation study included all comparable stroke registries maintained in industrialized countries (Italy, France, United Kingdom, Denmark, Norway , United States, and Australia). Eleven community-based stroke registries w ith similar high proportions of radiologically confirmed diagnoses based on standard definitions were identified. Incidence rates of first-ever stroke from the prospective L'Aquila registry and from the other registries were compared after age and sex standardization to the 1996 European population. The rates were then correlated with the proportion of individuals aged 65 and over in the corresponding resident populations by means of the Poisson regression analysis. Results: In the L'Aquila registry, the crude annual in cidence of first-ever stroke was 281/100,000 (95% confidence interval 271-2 93) based on 2,515 patients included during a 3-year period. The rate stand ardized to the European population was 249/100,000. Standardized incidence ratios indicated a significant excess of first-ever strokes in the L'Aquila registry up to 51% with respect to most of the com pared studies. A signif icant correlation was also found between crude (p < 0.0001) and standardize d (p = 0.0012) stroke incidence rates and proportions of individuals aged 6 5 and over in the different populations. Conclusions: The L'Aquila experien ce suggests that any further agi ng of a population will increase the strok e occurrence for both the reasons of a direct and predictable effect of the growing proportion of elderly individuals within that population and a dis proportionately increased stroke risk in the older age groups. Copyright <( c)> 2001 S. Karger AG, Basel.