Level of systolic blood pressure within the normal range and risk of recurrent stroke

Abstract

Context: Recurrent stroke prevention guidelines suggest that larger reductions in systolic blood pressure (SBP) are positively associated with a greater reduction in the risk of recurrent stroke and define an SBP level of less than 120 mm Hg as normal. However, the association of SBP maintained at such levels with risk of vascular events after a recent ischemic stroke is unclear.

Objective: To assess the association of maintaining low-normal vs high-normal SBP levels with risk of recurrent stroke.

Design, setting, and patients: Post hoc observational analysis of a multicenter trial involving 20,330 patients (age ≥50 years) with recent non-cardioembolic ischemic stroke; patients were recruited from 695 centers in 35 countries from September 2003 through July 2006 and followed up for 2.5 years (follow-up ended on February 8, 2008). Patients were categorized based on their mean SBP level: very low-normal (<120 mm Hg), low-normal (120-<130 mm Hg), high-normal (130-<140 mm Hg), high (140-<150 mm Hg), and very high (≥150 mm Hg).

Main outcome measures: The primary outcome was first recurrence of stroke of any type and the secondary outcome was a composite of stroke, myocardial infarction, or death from vascular causes.

Results: The recurrent stroke rates were 8.0% (95% CI, 6.8%-9.2%) for the very low-normal SBP level group, 7.2% (95% CI, 6.4%-8.0%) for the low-normal SBP group, 6.8% (95% CI, 6.1%-7.4%) for the high-normal SBP group, 8.7% (95% CI, 7.9%-9.5%) for the high SBP group, and 14.1% (95% CI, 13.0%-15.2%) for the very high SBP group. Compared with patients in the high-normal SBP group, the risk of the primary outcome was higher for patients in the very low-normal SBP group (adjusted hazard ratio [AHR], 1.29; 95% CI, 1.07-1.56), in the high SBP group (AHR, 1.23; 95% CI, 1.07-1.41), and in the very high SBP group (AHR, 2.08; 95% CI, 1.83-2.37). Compared with patients in the high-normal SBP group, the risk of secondary outcome was higher for patients in the very low-normal SBP group (AHR, 1.31; 95% CI, 1.13-1.52), in the low-normal SBP group (AHR, 1.16; 95% CI, 1.03-1.31), in the high SBP group (AHR, 1.24; 95% CI, 1.11-1.39), and in the very high SBP group (AHR, 1.94; 95% CI, 1.74-2.16).

Conclusion: Among patients with recent non-cardioembolic ischemic stroke, SBP levels during follow-up in the very low-normal (<120 mm Hg), high (140-<150 mm Hg), or very high (≥150 mm Hg) range were associated with increased risk of recurrent stroke.

Trial registration: clinicaltrials.gov Identifier: NCT00153062.