Stroke in 85-year-olds: prevalence, incidence, risk factors, and relation to mortality and dementia.

BACKGROUND AND PURPOSE Stroke and dementia are major health problems in the elderly. We examined the prevalence and incidence of stroke and their relation to dementia in a representative sample of 494 subjects 85 years of age from Gothenburg, Sweden, who were followed up to 88 years of age. METHODS Information on stroke was obtained from an inpatient hospital linkage system, death certificates, self-reports, and key informants. Dementia was defined according to the Diagnostic and Statistical Manual of Mental Disorders, third revision. RESULTS The prevalence of stroke at 85 years of age was 18.8% (self-reports, 10.7%; key informants, 13.2%; register data, 13.0%). The incidence of stroke between 85 and 88 years of age was 57.2/1000 person-years (men, 32.5/1000 person-years; women. 66.9/1000 person-years; self-reported, 30.8/1000 person-years; key informants, 38.5/1000 person-years; register data, 45.4/1000 person-years). Female sex (risk ratio [RR], 2.1; 95% confidence interval [CI], 1.0 to 4.8) and higher systolic blood pressure (per 10 mm Hg: RR, 1.14; 95% CI, 1.02 to 1.28) were associated with higher incidence of stroke. Baseline stroke was related to increased mortality in women and higher prevalence but not incidence of dementia. There was an association between incidence strokes and incidence dementia between 85 and 88 years of age (RR, 3.8; 95% CI, 2.2 to 6.7). CONCLUSIONS One fifth of 85-year-olds had stroke, and half of those were demented. In this age, it is important to use several sources of information to detect stroke because of the high number of demented. High blood pressure increases stroke risk also in the very old, which is important in relation to prevention.