Time trends in incidence and case fatality of ischemic stroke: the tromsø study 1977-2010

Abstract

Background and purpose: Ischemic stroke incidence has declined in industrialized countries the last decades, with possible exception for the youngest age groups. We estimated age- and sex-specific trends in incidence and case fatality of first-ever ischemic stroke between 1977 and 2010 in a Norwegian municipality.

Methods: Age-adjusted time trends in incidence from 1977 to 2010 were estimated by fractional polynomial and Poisson regression, and case fatality by logistic regression in 36 575 participants of the population-based Tromsø Study.

Results: There were 1214 first-ever ischemic strokes within a total follow-up time of 611 176 person-years. The overall age- and sex-adjusted incidence decreased by 24% in 1995 to 2010. In women aged 30 to 49 years, the incidence increased significantly from 1980 to 2010. In men aged 30 to 49 years, there was a nonsignificant, rising trend from 1977 to 2010. Men aged 50 to 64 years had similar incidence in 2010 compared with 1989. From the mid-1990s to 2010, the incidence declined significantly in women aged 50 to 74 years and in men aged 65 to 74 years, but remained stable in those aged ≥75 years. Case fatality decreased significantly in men aged 30 to 84 years from 1995 to 2010, whereas there was no significant change in women.

Conclusions: Age-adjusted incidence of first-ever ischemic stroke increased in young women, declined in women aged 50 to 74 years and men aged 65 to 74 years and remained stable among the oldest. Case fatality declined in men aged 30 to 84 years, but not in women.

Keywords: case fatality; cerebral infarction incidence; cohort study; epidemiology; stroke.