Antihypertensive therapy given to people with prehypertensive blood pressure levels reduced the risk of stroke by 22 percent, according to a meta-analysis of 16 randomized controlled clinical trials. The study results appeared Dec. 8 in Stroke.
Ilke Sipahi, MD, of University Hospitals Case Medical Center in Cleveland, and colleagues wanted to explore whether the use of therapies that lower blood pressure reduce the risk of stroke in patients whose blood pressure (BP) falls between 120 mm Hg to 139 mm Hg systolic and 80 mm Hg to 89 mm Hg diastolic blood pressure. The range known as prehypertensive is prevalent in some populations and often progresses to hypertension (Lancet 2001;358:1682-1686).
They speculated that the protective properties of antihypertensives might be beneficial in this group of patients, who currently are not considered appropriate for treatment. They also noted that no clinical trials have been conducted targeting this specific indication and patient population, but that several placebo-controlled trials to test antihypertension treatments for other conditions had captured data on patients with average blood pressure levels in the prehypertensive range.
Using MEDLINE, they identified published studies on 16 randomized trials that included a baseline prehypertensive BP reading in a group receiving antihypertension therapy and in a placebo group, and that also reported stroke incidence in their outcomes. In all, they collected data on 70,664 patients.
In initial analyses, they found that in 14 of the 16 trials, the treatment group had fewer strokes compared with the placebo group. To test if one trial was skewing results, they ran analyses eliminating each study once and found the risk reduction remained statistically significant each time.
They also ran analyses looking at each antihypertensive drug class and found benefits across the board. Compared with placebo, patient groups who received:
- ACE inhibitors had a 25 percent lower risk of stroke;
- Calcium channel blockers had a 25 percent lower risk of stroke; and
- ARBs trended toward a reduction in risk.
“The absolute risk of stroke in the treatment arm was 2.01 percent,” they wrote. “The absolute risk of stroke in the placebo arm was 2.61 percent. To prevent one stroke, 169 patients with prehypertensive blood pressure levels had to be treated with a blood pressure-lowering medication for 4.3 years.”
In their discussion, the authors argued that 140/90 mm Hg and above as the threshold for hypertension was arbitrary, and pointed to trials that showed an association between prehypertensive BP levels and adverse cardiac events.
They also highlighted limitations to their study, most notably that it relied on average systolic BP at baseline. They lacked individual patient histories and therefore could not discern if some patients were formerly hypertensive but through treatment achieved a prehypertensive reading. They also acknowledged that the trials did not report outcomes uniformly.