Stroke incidence and survival among middle-aged adults - 9-year follow-up of the Atherosclerosis Risk in Communities (ARIC) cohort

Background and Purpose-Although stroke mortality rates in the United States are well documented, assessment of incidence rates and case fatality are l ess well studied. Methods-A cohort of 15 792 men and women aged 45 to 64 years from a populat ion sample of households in 4 US communities was followed from 1987 to 1995 , an average of 7.2 years. Incident strokes were identified through annual phone contacts and hospital record searching and were then validated. Results-Of the 267 incident definite or probable strokes, 83% (n=221) were categorized as ischemic strokes, 10% (n=27) were intracerebral hemorrhages, and 7% (n=19) were subarachnoid hemorrhages. The age-adjusted incidence ra te (per 1000 person-years) of total strokes was highest among black men (4. 44), followed by black women (3.10), white men (1.78), and white women(1.24 ). The black versus white age-adjusted rate ratio (RR) for ischemic stroke was 2.41 (95% CI, 1.85 to 3.15), which was attenuated to 1.38 (95% CI, 1.01 to 1.89) after adjustment for baseline hypertension, diabetes, education l evel, smoking status, and prevalent coronary heart disease. There was a ten dency for the adjusted case fatality rates to be higher among blacks and me n, although none of the case fatality comparisons across sex or race was st atistically significant. Conclusions-After accounting for established baseline risk:factors, blacks still had a 38% greater risk of incident ischemic stroke compared with whit es. Identification of new individual and community-level risk factors accou nting for the elevated incidence of stroke requires further investigation a nd incorporation into intervention planning.