Effect of blood pressure during the acute period of ischemic stroke on stroke outcome: a tertiary analysis of the GAIN International Trial

Background and Purpose-The effects of blood pressure (BP) and its fluctuations during the acute phase on the clinical course of ischemic stroke are incompletely understood. We tested the hypotheses that baseline mean arterial BP [MAP=(2Xdiastolic BP+systolic BP)/3], weighted average MAP, and an increase or decrease of >30% from baseline MAP are independently associated with stroke outcome. Methods-We studied the 1455 patients with ischemic stroke in the Glycine Antagonist (Gavestinel) in Neuroprotection (GAIN) International Trial. BP management was at the discretion of investigators and was measured at 0, 0.5, 4, 12, 12.25, 60, and 60.25 hours. Outcome was assessed by mortality, Barthel Index ( dead or 0 to 55 versus 60 to 90 versus greater than or equal to95), National Institutes of Health Stroke Scale (NIHSS) score (dead or greater than or equal to2), and Rankin Scale ( dead or greater than or equal to2). Cox proportional-hazards and stepwise logistic regression modeling corrected for demography, medical history, stroke severity, and clinical subtype. Results-Elevated weighted average MAP was associated with poor outcome assessed by mortality at 3 months (hazard ratio, 1.16; 1.06 to 1.27 per 10 mm Hg), NIHSS score (odds ratio [ OR] 1.14; 95% confidence interval [CI], 1.01 to 1.28), and Barthel Index at 1 month ( OR, 1.12; 95% CI, 1.03 to 1.23). A 30% increase from baseline MAP was associated with poor outcome assessed by NIHSS score and Barthel Index at 1 and 3 months and by Rankin score at 1 month (OR, 2.01; 95% CI, 1.16 to 3.49 to OR, 3.03; 95% CI, 1.30 to 7.02). Conclusions-Baseline MAP was not associated with poor ischemic stroke outcome. However, variables describing the course of BP over the first 2.5 days have a marked and independent relationship with 1- and 3-month outcome.