Framingham study finding Even normal blood pressure may boost a person’s risk of cardiovascular disease if the pressure hovers near the upper limit of normal.
“When a person’s blood pressure is below 140/90 mm Hg, most people think that’s fine and there’s no need to pay attention to cardiovascular risk,” Dr. Donna S. Hanes said at the annual meeting of the American College of Physicians–American Society of Internal Medicine.
But the results of a recently reported epidemiologic analysis documented the risk from high-normal pressure, when the systolic pressure is 130-139 mm Hg and the diastolic is 85-89 mm Hg.
People with blood pressures at this level need to work on lowering their pressure, not with drugs but with lifestyle modifications like diet, exercise, and weight loss, said Dr. Hanes of the University of Maryland, Baltimore.
The study cited by Dr. Hanes involved 6,859 people who participated in the Framingham Heart Study.
All of these people entered the study free of hypertension and cardiovascular disease.
The study participants were divided into three groups according to blood pressure: People with optimal blood pressure, less than 120/80 mm Hg; those with normal pressure, 120-129/80-84 mm Hg; and those with high-normal pressure, 130-139/85-89 mm Hg.
The incidence of cardiovascular disease events was tracked in the study participants during an average follow-up of 11 years.
During the follow-up period, the incidence of cardiovascular disease events in men was 30% higher in those with normal blood pressure and 60% higher in those with high-normal pressure, compared with the men who had optimal blood pressure, investigators reported in a journal article that was published last November (N. Engl. J. Med. 345:1291-97, 2001).
The increased risk of the high-normal group was statistically significant and took into account the between-group differences in age and other cardiovascular risk factors such as serum lipid levels and diabetes.
Among the women in the study, those with high-normal pressure had a risk-adjusted, 80% increased risk of developing cardiovascular disease, compared with women who started with an optimal blood pressure.
A goal blood pressure of less than 140/90 mm Hg was established for certain high-risk patients, such as those with diabetes, in the most recent U.S. recommendations on blood pressure treatment by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.
But these findings from the Framingham Heart Study are the first to document a substantial risk from high-normal blood pressure in people without any other risk of cardiovascular disease, according to Dr. Hanes.
Although the recent Framingham analysis presents compelling evidence on the danger of high-normal blood pressure, the data do not justify changing the threshold for starting antihypertensive drug treatment since the evidence is entirely epidemiologic.
For this reason, Dr. Hanes only felt comfortable recommending lifestyle interventions to lower blood pressure in these people.
It’s unlikely that a study will be done to test the benefits of drug treatment for otherwise healthy adults with high-normal blood pressure, because the study would require either a huge number of subjects or a very long follow-up period, said Dr. Hanes.