Healthy Skepticism Library item: 1124

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Publication type: news

Grady D.
U.S. Lowers 'Normal' Levels for Blood Pressure Readings
NY Times 2003 May 15
http://www.nytimes.com/2003/05/14/health/14CND-BLOO.html

Full text:

Millions of people who in the past would have been told that their blood pressure was normal or “high normal” should now be told that they actually have a condition called prehypertension that threatens their health, according to guidelines issued yesterday by government health experts.

The new category includes 45 million Americans whose blood pressure is 120 to 139 millimeters of mercury systolic (the top number) or 80 to 90 diastolic (bottom number).

People with readings in this range do not have high blood pressure yet and do not need to take medication.

But the new guidelines advise doctors that such people are likely to develop high blood pressure, and should be urged to try to lower their pressure by losing excess weight, exercising more, quitting smoking, cutting back on salt, having no more than one or two alcoholic drinks a day and eating more fruits, vegetables and low-fat dairy products.

The guidelines and a report were issued by the National High Blood Pressure Education Program, part of the National Heart, Lung and Blood Institute. They were posted yesterday on the Web site of the Journal of the American Medical Association, at www.jama.com, and will be published in the journal’s May 21 issue.

It has long been known that elevated blood pressure is a serious health threat, but this report represents the first time that the government’s blood pressure panel has flagged relatively low readings as a harbinger of disease.

A statement issued by the institute said the new recommendations were based on studies showing that artery damage and an increased risk of cardiovascular disease can begin even at blood pressure levels that until recently were thought to be normal. The risk of heart disease and stroke starts to rise at readings as low as 115/75, and doubles for each increase of 20/10 millimeters of mercury.

The report urges doctors and patients to take high blood pressure more seriously and treat it more aggressively, often with more than one drug. High blood pressure greatly increases the risk of heart disease, stroke and kidney failure. Heart disease, which kills more than 700,000 Americans a year, is the nation’s leading cause of death.

“The prehypertension area is important,” Dr. Edward J. Roccella, coordinator of the program, said. “We want people to act long before the disease is established, to prevent the progressive blood pressure rise.”

In addition to weight loss and diet changes, he said, the program was recommending 30 minutes of exercise most days, which could be broken into two 15-minute walks.

“If you don’t have time for physical activity, you will have time for illness,” Dr. Roccella said. “Illness doesn’t make an appointment.”

Blood pressure tends to increase steadily with age, and the new report says that even people whose readings are normal at the age of 55 have a 90 percent chance of eventually developing high blood pressure, although changes in diet and exercise can ward it off.

The guidelines define normal blood pressure as a reading below 120/80 millimeters of mercury.

High blood pressure is defined as any reading above 140 millimeters of mercury systolic (top number) or above 90 diastolic (bottom number). The top number is the pressure in the arteries when the heart is contracting, and the bottom number is the pressure when the heart is at rest between beats.

Information is available at www.nhlbi.nih.gov/guidelines /hypertension.

The last report from the same group, in 1997, allowed slightly higher pressures to be classified as normal, and gave the label high normal to systolic levels of 130 to 139 and diastolic levels of 85 to 89. The new guidelines eliminate the high-normal category.

Fifty million Americans, or one in four adults, have high blood pressure, also called hypertension, and only a third of them have it under control. A billion people worldwide are affected. In most cases, the cause is not known.

Hypertension has no symptoms, and 30 percent of those who have it are not aware of it. The pressure does its damage by injuring the arteries and causing them to stiffen, which increases the pressure more.

The new report suggests that better control of blood pressure could drastically reduce the number of deaths from heart attack, heart failure, stroke and kidney disease. Lowering high blood pressure may also reduce the progression of dementia and cognitive impairment, which are more common in people with hypertension.

The report also states that controlling hypertension has been associated with a 35 to 40 percent average reduction in the incidence of stroke, a 20 to 25 percent reduction in heart attacks and more than a 50 percent reduction in heart failure. The report also estimates that in patients with other cardiovascular risk factors, a sustained 12-point reduction in systolic blood pressure over 10 years will prevent one death for every 10 patients treated.

Although for many years doctors believed, and advised patients, that the more important number in a blood pressure reading was the bottom one, or diastolic pressure, in the last decade or so studies have shown that the top number is at least as important, especially in older people, in whom it tends to rise. Drugs to lower blood pressure usually work for both readings, Dr. Roccella said.

When blood pressure is high enough to require medication, the goal for most people is to get it below 140/90, although those with diabetes or kidney disease are urged to aim for 130/80. Even though normal is considered 120/80, that is simply not a realistic goal for many patients, Dr. Roccella said.

Several classes of drugs are used to treat hypertension, including diuretics, commonly called water pills, as well as beta blockers, calcium channel blockers and ACE inhibitors. Some people can get results with one drug, but those with higher levels often need more than one, the report said. Many of the medicines have been combined so that patients can take two drugs in a single pill.

Many of the drugs can have side effects like lightheadedness, coughing and sexual problems, but not all patients suffer from them. Those who do can often switch to a different type of drug that will lower blood pressure without causing problems, said Dr. Aram Chobanian, dean of the Boston University Medical School and chairman of the committee that produced the guidelines.

“We wouldn’t say, `Stay on one line of drugs if you’re having side effects,’ “ Dr. Chobanian said.

The report notes that for unknown reasons African-Americans have better results with diuretics and calcium blockers than with beta blockers, ACE inhibitors or angiotensin receptor blockers, and that blacks are also more likely than whites to suffer side effects from ACE inhibitors.

The report says that many people benefit from diuretics, alone or in combination, but adds that they are underused and should probably be prescribed more often.