Elevated midlife blood pressure increases stroke risk in elderly persons: the Framingham Study.

BACKGROUND: Stroke risk predictions are traditionally based on current blood pressure (BP). The potential impact of a subject's past BP experience (antecedent BP) is unknown. We assessed the incremental impact of antecedent BP on the risk of ischemic stroke.
METHODS: A total of 5197 stroke-free subjects (2330 men) in the community-based Framingham Study cohort were enrolled from September 29, 1948, to April 25, 1953, and followed up to December 31, 1998. We determined the 10-year risk of completed initial ischemic stroke for 60-, 70-, and 80-year-old subjects as a function of their current BP (at baseline), recent antecedent BP (average of readings at biennial examinations 1-9 years before baseline), and remote antecedent BP (average at biennial examinations 10-19 years earlier), with adjustment for smoking and diabetes mellitus. Models incorporating antecedent BP were also adjusted for baseline BP. The effect of each BP component (systolic BP, diastolic BP, and pulse pressure) was assessed separately.
RESULTS: Four hundred ninety-one ischemic strokes (209 in men) were observed in eligible subjects. The antecedent BP influenced the 10-year stroke risk at the age of 60 years (relative risk per SD increment of recent antecedent systolic BP: women, 1.68 [95% confidence interval, 1.25-2.25]; and men, 1.92 [95% confidence interval, 1.39-2.66]) and at the age of 70 years (relative risk per SD increment of recent antecedent systolic BP: women, 1.66 [95% confidence interval, 1.28-2.14]; and men, 1.30 [95% confidence interval, 0.97-1.75]). This effect was evident for recent and remote antecedent BP, consistent in hypertensive and nonhypertensive subjects, and demonstrable for all BP components.
CONCLUSIONS: Antecedent BP contributes to the future risk of ischemic stroke. Optimal prevention of late-life stroke will likely require control of midlife BP.