The time course and determinants of blood pressure within the first 48 h after ischemic stroke

BACKGROUND AND PURPOSE: Previous research suggests that blood pressure falls acutely after ischemic stroke. We aimed to further characterize this fall with a statistical technique that allows the application of regression techniques to serial blood pressure outcome data. METHODS: In a prospectively recruited ischemic stroke cohort, systolic (SBP) and diastolic (DBP) blood pressure was recorded every 4 h until 48 h after stroke. Potential determinants of blood pressure, including stroke severity and acute infection, were also recorded. Mixed effects models were used to model serial blood pressure measurements over time, adjusted for significant determinants. RESULTS: In 156 patients, SBP and DBP fell by 14.9 mm Hg (95% CI 6.2-22.6 mm Hg) and 6.2 mm Hg (95% CI 1.4-10.6 mm Hg), respectively, over the first 48 h after stroke. SBP was higher in patients with premorbid hypertension, a previous history of stroke or TIA, current alcohol use, increasing age, stroke of mild to moderate severity (NIHSS 3-13) and in patients treated with antihypertensives. SBP was lower in smokers. There was a progressive rise in SBP in patients with acute infection. No factors other than time were associated with DBP. CONCLUSIONS: The use of mixed effects models has identified a linear SBP and DBP fall over the first 48 h after stroke. The timing and magnitude of this fall should be accounted for in the design of future prognostic and intervention studies.