The National Institutes of Health (NIH) plans to send a clinical advisory to 250,000 U.S. health professionals warning that millions of older Americans are at risk of dangerous complications because many doctors are not properly treating high blood pressure.
The advisory follows new findings from the long-term Framingham Heart Study showing the dangers of not treating people with a type of hypertension called elevated systolic high blood pressure. Systolic blood pressure is produced as the heart contracts and pumps blood to the body. It is traditionally expressed as the first or higher number of a blood pressure reading, such as the "120" in the reading "120 over 80."
Until recent years, the systolic reading had often not been considered a significant indicator of blood pressure problems. The government advisory will urge more aggressive treatment of elevated systolic blood pressure.
"The message from this study is that you cannot ignore systolic pressure," said Claude Lenfant, director of the National Heart, Lung and Blood Institute (NHLBI), which is part of NIH.
An estimated 43 million people in the United States have high blood pressure, according to the National Center for Health Statistics, and the prevalence rises with age. At least half of Americans age 65 and older are estimated to have high blood pressure, and three of every four in that group have elevated systolic blood pressure. In some ethnic groups, such as African Americans, the rates are even higher.
Left uncontrolled, high blood pressure significantly increases the risk of heart attacks, strokes and kidney disease. It is also a leading cause of congestive heart failure, a chronic condition in which the heart fails to pump efficiently. An estimated 4.6 million Americans suffer from heart failure annually, and it is one of the most common causes of hospitalization among Medicare recipients.
Until now, most of the emphasis of blood pressure treatment has been on controlling diastolic blood pressure--the pressure that occurs in blood vessels between heartbeats and the second number reported when blood pressure is given. Keeping diastolic blood pressure in check is the chief way that the Food and Drug Administration judges the effectiveness of new blood pressure medications.
The problem is that diastolic blood pressure generally plateaus after age 60 and usually declines with advancing age--a fact that seems to make it less useful for monitoring the health of older individuals.
The latest Framingham findings, which appear this month in the journal Hypertension, point to the dangers of relying on diastolic blood pressure alone to treat those 60 and older and show how systolic blood pressure is a far more accurate predictor of future heart attacks, strokes, kidney problems and congestive heart failure.
"This is the fire alarm that says, 'Let's pay more attention to systolic blood pressure,' " said Edward J. Roccella, coordinator of NHLBI's National High Blood Pressure Education Program.
Doctors long thought that rising systolic blood pressure was an unavoidable consequence of aging and took few steps to keep it in check. The rule of thumb was to take a person's age and add it to 100 to set a so-called "normal" systolic blood pressure level. Using that equation, a reading of 180 was considered an acceptable systolic blood pressure for an 80-year-old.
But in 1997, the NIH's Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure issued new guidelines defining high blood pressure as systolic measurements above 140 and diastolic higher than 90. Optimal blood pressure, the committee's report concluded is 120/80 or lower, and it also set other blood pressure categories including "high normal" blood pressure (130/85 to 139/89), stage 1 high blood pressure (140/90 to 159/99); stage 2 high blood pressure (160/100 to 179/109) and stage 3 high blood pressure (180/110 or higher).
The Framingham study used those guidelines to examine nearly 5,000 men and women whose average age was 58. About 40 percent of participants had elevated blood pressure--that is, a reading of 130/85 or higher.
The researchers then focused on 1,488 participants with high-normal blood pressure levels who were potentially eligible for drug therapy. Using diastolic measurements, only one-third of these participants would have qualified for blood pressure treatment. But when the team looked at systolic blood pressure levels, 94 percent needed treatment.
"Our data indicates that systolic blood pressure plays a greater role than diastolic blood pressure in determining both blood pressure stage and eligibility for therapy," the team of researchers led by Daniel Levy concluded.
The importance of systolic blood pressure was also highlighted by another recent study, conducted by the same team of researchers and published in July in the journal Circulation. That study found that the risks of coronary heart disease rose 35 percent for every 10 points of elevated systolic blood pressure. By comparison, the same rise in diastolic blood pressure produced about a 14 percent increased risk, Levy and his colleagues reported.
Based on such findings, "it is no longer permissible for us [or our colleagues or our patients] to think that a systolic blood pressure of '100 plus your age' is acceptable," said Henry R. Black, chairman of preventive medicine at the Rush-Presbyterian-St. Luke's Medical Center in Chicago in an editorial accompanying the study. "Yet many still do not know this, and many have trouble giving up that antiquated idea."
Only about a third of Americans with high blood pressure are aware of their condition, according to the National Health and Nutrition Examination Survey (NHANES), which was conducted from 1991 to 1994 by the U.S. Centers for Disease Control and Prevention. Among the 68 percent of participants who had been diagnosed with high blood pressure, NHANES found that only about half received treatment. Just about a quarter of those reduced their blood pressure to safe levels through a combination of lifestyle changes or drugs.
The authors of the new studies concluded that guidelines for blood pressure treatment need to acknowledge the greater role that systolic blood pressure plays in determining the extent of high blood pressure, risk of complications, eligibility for therapy and benefits of treatment.
"It is crucial that we inform our patients, especially our older patients, that they must ask about their systolic blood pressure and not be satisfied if it is above 140," Black noted.
To help increase awareness, NHLBI plans to launch a public education program this fall underscoring the importance of treating elevated systolic blood pressure. "If your blood pressure isn't 140/90 or less, you need to ask your doctor why and what you can do to lower it," said NHLBI's Roccella.
Weight loss and diet modifications such as limiting sodium and increasing foods containing potassium, magnesium and calcium are among the first means of treatment. So, too, are exercise, smoking cessation, reduction of saturated fat and limiting alcohol to no more than one ounce per day--about the amount found in two ounces of 100-proof whiskey or two glasses of wine or two 12-ounce beers. (Women and lighter-weight adults should consume no more than half that amount of alcohol daily, according to the recommendations.)
For those with additional risk factors, such as diabetes or a history of heart disease or stroke, medications are often prescribed to bring blood pressure under control more quickly. Among the many drugs used are diuretics, beta blockers, calcium channel blockers and ACE inhibitors.
Such drugs "work well and are rather economical in terms of preventive care," said Edward D. Frohlich, editor-in-chief of Hypertension. "The [potential] dividends are great."
Even so, keeping systolic blood pressure at normal levels can be challenging. The Hypertension Optimal Treatment Study, a large clinical trial led by Swedish researchers and conducted in 26 countries, found that physicians successfully reduced diastolic blood pressure to 90 or less in patients more than 90 percent of the time. But systolic blood pressure was far more difficult to control, with 60 percent or less of patients reducing their systolic blood pressure levels to 140 or lower, even with the help of multiple drugs.
The clinical advisories will warn health professionals to lower systolic blood pressure slowly to avoid complications, such as fainting in older patients. "The suggestions are to start with lifestyle changes, use medications at half dose and to go slowly," Roccella said.
More information about high blood pressure is available from the National Heart, Lung and Blood Institute, which can be reached by telephone at 1-800-575-9355 or on the World Wide Web at www.nhlbi.nih.gov.
Blood Pressure Categories for Adults
An estimated 43 million people in the United States have high blood pressure, putting them at risk of heart attacks, strokes, kidney disease and congestive heart failure.
In the past, treatment has been centered on controlling diastolic blood pressure -- the pressure that occurs in blood vessels between heartbeats and the second, or lower, number reported in millimeters of mercury when blood pressure is measured. However, health experts are now urging that high systolic pressure -- the pressure produced as the heart contracts and the first, or higher, number reported -- also be treated.
Category Systolic Diastolic
Optimal <120 and <80
Normal <130 and <85
High-normal 130-139 or 85-89
Stage 1 140-159 or 90-99
Stage 2 160-179 or 100-109
Stage 3 >180 or >110
SOURCE: The National Heart, Lung and Blood Institute