By Will Boggs, MD

WESTPORT, CT (Reuters Health) – Blood pressure currently classified as high-normal is associated with an increased risk of cardiovascular disease, according to a report in the November 1st issue of The New England Journal of Medicine.

Previous work has shown a continuum of cardiovascular risk across levels of blood pressure, the authors explain, but little information is available about the absolute and relative risks of cardiovascular disease in individuals with high-normal or normal blood pressure.

Dr. Ramachandran S. Vasan from the Framingham Heart Study in Massachusetts and colleagues investigated the association between baseline blood pressure and cardiovascular disease incidence in 6859 subjects.

A quarter of the subjects had high-normal blood pressure (systolic pressure 130 to 139 mm Hg or diastolic pressure 85 to 89 mm Hg), a third had normal blood pressure (systolic pressure 120 to 129 mm Hg or diastolic pressure 80 to 84 mm Hg), and the remainder had optimal blood pressure (systolic pressure less than 120 mm Hg and diastolic pressure less than 80 mm Hg).

Men under age 65 with high-normal blood pressure faced a 10-year cumulative cardiovascular disease incidence of 8%, a rate of 9.2 events per 1000 person-years, the authors report. The rate in men over age 65 was especially high, 28.1 events per 1000 person-years, translating into a 10-year cumulative cardiovascular disease incidence of 25%.

Results were similar among women. The younger group of women with high-normal blood pressure experienced 4.7 events per 1000 person-years (a 10-year cumulative incidence of 4%), the report indicates. The older group experienced 19.5 events per 1000 person-years (a 10-year cumulative incidence of 18%).

Compared with subjects having optimal blood pressure, those having high-normal blood pressure faced substantially higher hazard ratios for cardiovascular disease (2.5 for women and 1.6 for men), the researchers note. Normal blood pressure, too, elevated the risk of cardiovascular disease 1.5-fold for women and 1.3-fold for men compared with optimal pressure.

"There is a continuum of increased cardiovascular disease risk that begins at levels below what is currently regarded as hypertension," Dr. Vasan told Reuters Health. "High-normal blood pressure cannot be ignored. It is associated with increased cardiovascular disease risk, more so in the elderly."

"Lifestyle measures to lower blood pressure seem reasonable in this group and should be discussed with patients," Dr. Vasan said. "Optimal blood pressure is clearly the desirable level of blood pressure."

"[This finding] that high-normal blood pressure is more akin to high blood pressure than it is to normal pressure is an important advance in our understanding of the magnitude of the problem," Dr. Julio A. Panza from Washington Hospital Center in Washington, DC writes in a related editorial.

N Engl J Med 2001;345:1291-1297,1337-1340.