Is The Rate Of Ischemic Stroke Incidence Changing Differentially Over Time For Women And Men?

Background: A surge of midlife (age 55-64 years) stroke in women, and not in men, has previously been reported using prevalence data from NHANES. However it is not clear if this same finding would be seen within age- and gender-specific incidence rates of stroke. We sought to examine the incidence of ischemic (IS) stroke and the gender-specific trends over time in a population-based study of stroke epidemiology. Methods: Data from the population-based Greater Cincinnati and Northern Kentucky epidemiology of stroke study for adults (≥ 20 years) was used from three collection periods; 7/1993 to 6/1994, 1999, and 2005. We compared the IS stroke incidence rates in women versus men between the three study periods, in particular for the ages 35 to 65 years. Sex specific age, and race adjusted incidence rates and race adjusted, age and gender specific incidence rates were estimated and adjusted to the 2000 US population. Results: A total of 5166 incident IS strokes were identified: 1709 from 7/1993 to 6/1994, 1778 from 1999, and 1679 from 2005. These were 56% female, 18% black; mean age was 71.4 (13.7) years. Overall, IS stroke incidence declined in both women and men in 2005 compared to the previous time periods (p<0.01). However, there was a significant increase over time in stroke incidence seen in both men and women in the younger age groups in 2005, compared with 1993/94 (p<0.05). Conclusions: We found that stroke incidence is not changing differently over time for men and women. There has been an increase in IS stroke incidence in the young, but this is found in both men and women. The previously reported “surge” in middle-aged stroke prevalence may be related in part to increased rates of stroke in the young, with survival to middle-age, but our incidence findings do not explain the reported difference in prevalence found between women and men in the NHANES cohort.