New Definition of Hypertension Proposed

By Sherry Boschert

SAN FRANCISCO -- A new definition of hypertension proposed at the annual meeting of the American Society of Hypertension deemphasizes blood pressure readings and eliminates the label of prehypertension.

A "writing group" of ASH leaders penned the new definition to prompt clinicians to consider each individual patient's overall risk for cardiovascular disease, even if blood pressure numbers are considered normal, said Thomas Giles, M.D., president of the society and professor of medicine at Louisiana State University, New Orleans.

Basing diagnosis and management not just on blood pressures but on a patient's overall mix of risk factors might lead to earlier diagnosis and treatment, he said. Clinicians might better be able to spot the early stages of hypertension and treat to prevent damage to the heart, kidneys, brain, vasculature, eyes, and other targeted organs.

Factors to consider in assessing overall risk include age, sex, lipid levels, body mass index, smoking, family history, target-organ damage, and early markers of cardiovascular disease (including microalbuminuria, impaired glucose tolerance, or exaggerated blood pressure responses to stress tests).

The definition of hypertension is a moving target, modified multiple times in the seven iterations of guidelines by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC).

The proposed definition does away with the classification of prehypertension contained in JNC 7 (defined as a systolic blood pressure of 120-139 mm Hg or a diastolic pressure of 80-89 mm Hg). People formerly labeled as prehypertensive would be considered either hypertensive or normal, avoiding stigma and worry for some.

For example, one patient with a blood pressure of 130/80 mm Hg with signs of damage to the heart, kidneys, or eyes would be considered hypertensive, while another patient with the same blood pressure with no signs of vascular damage would be considered normal, Dr. Giles said.

More than 80% of hypertensive patients have comorbidities including obesity, glucose intolerance, hyperinsulinemia, left ventricular hypertrophy, elevated LDL-cholesterol or triglyceride levels, and reduced HDL-cholesterol levels. More than half of hypertensive patients have two or more of these comorbidities, a 2000 study showed.

Of the estimated 65 million U.S. residents who have hypertension, 58% are being treated, and only 31% have their blood pressure controlled to less than 140/90 mm Hg, Daniel Levy, M.D., said in a separate presentation at the meeting.

"We have existing guidelines--we're just not applying them. We have existing definitions--we're just not listening to them," said Dr. Levy of the National Heart, Lung, and Blood Institute. "Are we really ready for a new definition, or is it time we start practicing what we already know?"

Michael A. Weber, M.D., said in a separate presentation that the proposal is "a work in progress" moving toward a new definition of hypertension. Research is needed to determine how this broader concept of hypertension will translate into clinical practice, said Dr. Weber of the State University of New York Downstate Medical Center, Brooklyn, who helped write the definition.

The proposal generated some confusion. "Yesterday we had a plenary session on a new definition of hypertension," Thomas Pickering, M.D., of Columbia-Presbyterian Medical Center, New York, said in a separate presentation. "Having sat through it, I'm still not sure what the new definition is."