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Experts Recommend a New Way of Reading Blood Pressure

May 4, 2000 -- High blood pressure affects about 50 million people in the U.S. -- one in four adults -- and many of them don't even know they have it. The condition increases the risk of heart disease and stroke, and can lead to congestive heart failure, kidney damage, and blindness.

Now top experts have reversed the accepted notions of how to tell whether people have high blood pressure -- at least for middle-aged and older people.

When blood pressure is measured, there are two readings. The systolic pressure (taken while the heart beats) is the upper number, and the diastolic pressure (taken while the heart relaxes between beats) is the lower number. The reading is typically recorded as two numbers separated by a slash, such as 120/70 or 140/85.

Doctors have been trained to evaluate high blood pressure mainly by looking at the diastolic reading. But there is now substantial evidence showing that for middle-aged and older adults, the key indicator should be the upper figure, the systolic reading.

The coordinating committee of the National High Blood Pressure Education Program, representing a consensus among 45 agencies, has issued an advisory saying that systolic pressure should be the main measure used to detect and treat high blood pressure.

"This is a clarification," says Joseph L. Izzo Jr., MD, an author of the advisory statement. He is a professor of medicine and pharmacology at the State University of New York School of Medicine in Buffalo.

A re-analysis of the available information about blood pressure showed that it was time to make the change, Izzo says. The National Heart, Lung, and Blood Institute is launching a three-year campaign to make doctors and the public aware of the switch.

One reason the issue is important is that many people have high systolic readings and normal diastolic readings. "In this society, as people age, we see an increase in systolic blood pressure of approximately 1 mm per year," Izzo says. "The diastolic reading increases progressively to about age 55 and then begins to decline." This means that when the diastolic reading is used to determine who has high blood pressure, many people who need treatment aren't identified and treated.

Traditionally many physicians have used a rule of thumb that says acceptable systolic pressure readings could be "100 plus your age." That is wrong, the coordinating committee says. For everyone, at all ages, blood pressure levels should be below 140/90, it says. People with diabetes should lower their pressure to below 130/85, and those with kidney failure or heart failure should try to get their blood pressure even lower.

People need to pay attention to their blood pressure levels, says Daniel W. Jones, MD. "You need to know what your blood pressure is," he says. "If it is not controlled to below 140/90, you need to ask your practitioner about it." Jones, director of the Division of Hypertension at the University of Mississippi Medical Center in Jackson, is the American Heart Association's representative on the coordinating committee.

"We've been lax in treating the systolic reading," says John McAnulty, MD. But, he says, treatment decisions should be adjusted to each patient's circumstances. "There is always a trade-off because the therapies have their own drawbacks. The individual physician must balance, for each individual patient, whether the problems with the medications are justified by the expected benefits."

One of the challenges today, he adds, is that there are so many things to discuss during the typical office visit. "Blood pressure may be low on the list. Patients need to emphasize their interest in this topic, so it doesn't get lost on the radar screen."

Also, there are things everyone can do to prevent high blood pressure: Eat a healthy diet, get regular exercise, maintain a healthy weight, don't overindulge in alcohol. Even patients who now have good blood pressure readings should adopt a healthy lifestyle, he says.

As part of the just-launched educational campaign, the National Heart, Lung and Blood Institute is setting up a Web site on high blood pressure for consumers and physicians, available at www.nhlbi.nih.gov.