Prehypertension and the Continuum of Stroke Risk
Prehypertension, especially in the higher range, is associated with incident stroke.
To assess whether so-called prehypertension is associated with incident stroke, researchers conducted a meta-analysis of prospective cohort studies. The analysis included 518,520 participants from 12 studies originating in the U.S., China, Japan, and India. Prehypertension was defined as systolic blood pressure of 120 139 mm Hg or diastolic blood pressure of 80 89 mm Hg. In seven of the studies, prehypertension was further subdivided into a low range (120 129 mm Hg systolic or 80 84 mm Hg diastolic) and a high range (130 139 mm Hg systolic or 85 89 mm Hg diastolic).
Overall, prehypertension was associated with a significantly increased risk for stroke (relative risk, 1.55) that was driven by higher-range prehypertension (RR, 1.79). Lower-range prehypertension was not significantly associated with increased stroke risk. In subgroup analyses by baseline characteristics, the association was not affected by race/ethnicity, stroke endpoint (fatal vs. all stroke), stroke subtype (ischemic vs. hemorrhagic), or follow-up duration (<10 vs. ¥10 years). The association did not remain significant for people older than 65 and when study quality was only “fair.”
The authors conclude that prehypertension, especially in the higher range, is associated with incident stroke.
Comment: Hypertension is associated with stroke on a continuum of risk (Lancet Neurol 2002; 1:149). For example, mild, moderate, and severe hypertension are all associated with stroke risk, with the highest relative risk for stroke among those with the highest blood pressure, and the greatest absolute number of strokes in those with mild or “high-normal” blood pressure, a designation that includes prehypertension. The current findings support the concept of a continuum of risk for stroke with increasing blood pressure, especially among patients with higher-range prehypertension. However, whether lowering blood pressure in the prehypertension range will reduce stroke risk remains uncertain; this hypothesis deserves additional efficacy, safety, and cost-effectiveness testing. Currently, rigorous lifestyle modification is recommended for people with prehypertension. A blood pressure target <130/80 mm Hg has been recommended for those with, for example, diabetes mellitus, chronic renal disease, or carotid artery disease and for those with 10-year Framingham risk scores of ¥10% (Circulation 2007; 115:2761).
Philip B. Gorelick, MD, MPH
Dr. Gorelick is the John S. Garvin Professor and Head, Department of Neurology and Rehabilitation, University of Illinois College of Medicine at Chicago.
Published in Journal Watch Neurology October 18, 2011