Hypertension may be redefined — again.

At a recent meeting of hypertension experts, doctors proposed a new definition of hypertension, taking the emphasis away from the blood pressure numbers and placing it on a person's overall risk of heart disease and stroke.

It's not that your doctor won't take your blood pressure anymore. It's just that the reading will be one part of a global cardiovascular disease risk assessment that takes into account everything from whether you smoke to your cholesterol levels, as well as evidence of organ damage from hypertension or cardiovascular disease.

Smoking and high cholesterol are risk factors for cardiovascular disease.

Hypertension, or high blood pressure, is also linked to an increased risk of cardiovascular disease, such as heart attack and stroke. Cardiovascular disease is the No. 1 cause of death in the U.S. "The numbers are important, but the risk for hypertension is part of a continuum," says Thomas Giles, MD, president of the American Society of Hypertension (ASH) and an author of the definition. "You don't go from being well to being sick because your blood pressure reading went up one point."

The new definition is not a guideline for treatment but rather a wake-up call for doctors and patients to understand that treatment of hypertension requires attention to something more than just a number, says Giles, who is also a professor of medicine at the Louisiana State University School of Medicine in New Orleans.

"Under the new definition," he says, "statins that lower cholesterol might be considered antihypertensive drugs, and antidiabetes drugs might be considered antihypertensive drugs."
Giles, who outlined the new definition this weekend at the ASH annual meeting in San Francisco, says it is being finalized for publication in a major medical journal.

A New Definition of Hypertension

Federal guidelines that came out in 2003 classified hypertension by blood pressure reading. High blood pressure is considered to be a systolic blood pressure (the top number) of greater than 140 or a diastolic blood pressure (the bottom number) of greater than 90.

"Normal" blood pressure is less than 120/80.

The 2003 guidelines also placed nearly one in four Americans who once thought they had normal blood pressure levels into a prehypertension risk category. The prehypertension category includes about 45 million men and women who have a systolic blood pressure between 120 and 139 or a diastolic blood pressure of 80 to 89.

The new definition released this weekend changes this; it classifies "normal individuals" as having normal blood pressure, loosely defined as a systolic pressure of 115 and a diastolic pressure of 75 PLUS no signs of heart disease or stroke, few if any risk factors for cardiovascular disease, and no apparent damage from high blood pressure to the kidneys or other organs.

Cardiovascular risk factors include age, sex, abnormal cholesterol and triglyceride levels, obesity as measured by body mass index (BMI), smoking, and family history of cardiovascular diseases such as heart disease or stoke.

Hypertensive organ damage can occur in the heart, arteries, brain, kidneys, and eyes.

Stage I, or mild, hypertension includes patients with occasional or intermittent blood pressure elevations or early cardiovascular disease, several risk factors for cardiovascular disease, but no organ damage.

Stage III, or severe, hypertension involves marked and sustained blood pressure elevations or advanced cardiovascular disease and many risk factors. A person's cholesterol level may be abnormal, and kidneys or other organs may be damaged from the hypertension.

Stage II falls between the two.

'Good Riddance' to Prehypertension

The new definition also gets rid of the grey zone known as prehypertension, Giles tells WebMD.

Richard Devereux, MD, tells WebMD that "he's enthusiastic about the concept."

The new plan would redefine hypertension based on the actual level of risk, says Devereux, professor of medicine at Weill Medical College of Cornell University in New York.

He also supports the group's effort to get rid of the "confusing" prehypertension category.

The new approach will "guide treatment to the 5 or perhaps 10 million people in this ambiguous zone who actually need blood pressure-lowering medication and let the others stop worrying," Devereux says.

By Charlene Laino, reviewed by Charlotte E. Grayson, MD

SOURCES: American Society of Hypertension's 20th Annual Scientific Meeting and Exposition, San Francisco, May 14-18, 2005. Thomas Giles, MD, president, American Society of Hypertension; professor of medicine, Louisiana State University School of Medicine, New Orleans. Richard Devereux, MD, professor of medicine, Weill Medical College, Cornell University, New York.