The new category is a major change that could affect the approximately 45 million Americans with blood pressure as low as 120 over 80 — once thought to be a good level but now considered not low enough.
“We hope it’s going to catch people’s attention,” said Dr. Daniel W. Jones of the American Heart Association, a co-author of the National Heart, Lung and Blood Institute’s guidelines said of the new prehypertension category. “This is not to alarm people but simply deliver the message that … they are at higher risk for going on to develop hypertension and they need to take action.”
People with prehypertension should manage their blood pressure by loosing excess weight, engaging in regular physical activity, avoiding a salty diet and consuming no more than two alcoholic drinks a day. The guidelines do not recommend medication for those with prehypertension unless it is required for another condition, such as diabetes or chronic kidney disease.
“We don’t want to frighten the public, we want to get action. Even small changes in blood pressure are important,” said Dr. Aram Chobanian, dean of the Boston University school of medicine and chairman of committee that wrote the guidelines.
The guidelines also urge doctors to be far more aggressive in treating hypertension, noting that almost a third of people with high blood pressure don’t even know it. Plus, two-thirds of diagnosed patients don’t have the disease under control — too often because doctors hesitate to prescribe a second or third medication, Dr. Jones said.
An estimated 50 million Americans have high blood pressure, often called the silent killer because it may not cause symptoms until the patient has suffered damage. It raises the risk of heart attacks, strokes, heart failure, kidney damage, blindness and dementia.
A person’s blood pressure level is made up of two numbers representing systolic and diastolic pressure. The top number, systolic pressure, is the force of blood in the arteries as the heart beats. The bottom number represents diastolic pressure — the force of blood in the arteries as the heart relaxes between beats.
For those over 50, a high systolic number is more dangerous than a high diastolic reading. The reverse is true for younger people.
Until now, optimal blood pressure was considered 120 over 80 or lower; normal was up to 130 over 85; and levels above that were called borderline until patients reached the start of the hypertension range, 140 over 90.
But the new guidelines classify normal blood pressure as below 120 over 80 — and readings anywhere from 120 over 80 up to 140 over 90 as prehypertensive. The cut-off for high blood pressure did not change.
Recent scientific studies show that risk of heart disease actually begins rising once blood pressure creeps above 115 over 75, said guideline co-author Ed Roccella, a hypertension specialist.
There’s a doubling of risk for each 20-point rise in systolic pressure, or 10-point rise in diastolic pressure.
“Most of us will have hypertension if we live long enough,” said Roccella. Health officials hope that if people know they’re prehypertensive, they’ll make wiser lifestyle choices and thus stave off the blood-pressure creep that comes with age.
The guidelines will be published in next week’s Journal of the American Medical Association, but because of their importance they were released Wednesday on the journal’s Web site.