Hypertension and risk of stroke recurrence

Abstract

Background and purpose: Hypertension is a risk factor for initial stroke, but its relation to stroke recurrence is unclear. Therefore, we sought to analyze the effect of hypertension and its control on risk of stroke recurrence.

Methods: Within 1 month of onset, a population-based cohort of 662 patients from the Lehigh Valley with an initial stroke were enrolled. Hypertension was determined at enrollment by history. Blood pressure was also measured at enrollment and at each follow-up at 4- to 6-month intervals for up to 48 months (mean, 24 months). Stroke recurrence was verified by history, examination, and review of medical reports. Various criteria for control of blood pressure were defined. History of hypertension, measured blood pressure, and its control were analyzed in relation to stroke recurrence frequency using Kaplan-Meier and univariate, multivariate, and time-dependent Cox proportional hazards models.

Results: At enrollment, 59.4% of the cohort had a history of hypertension and 81 patients had a second stroke. Those with a history of hypertension had a significantly higher stroke recurrence rate than those without such a history (P = .01). Among those with measured diastolic blood pressure at enrollment > or = 95 mm Hg, 43% had a stroke recurrence by the end of the study compared with only 19% below this cutoff (P = .005). Recurrence risk was reduced in a multivariate analysis as quality of diastolic blood pressure control increased (relative risk = 8.4, 3.9, and 2.0 among those with poor, fair, and good control, respectively, compared with nonhypertensive subjects). Systolic blood pressure and its control appeared less or not significantly associated with stroke recurrence.

Conclusions: History of hypertension and elevated measured diastolic pressure after the initial stroke were associated with an increased risk of second stroke. Controlling diastolic pressure substantially reduced this risk.