"White-Coat" Hypertension Not Serious Health Threat, Study Says

November 02, 1998

DALLAS, November 3 -- Seeing a doctor or a nurse with a blood pressure monitor raises some people's blood pressure, but researchers say this "white-coat" hypertension is temporary and does not pose as high a risk for heart disease as sustained high blood pressure.

For 50 years, doctors treated patients with white-coat hypertension -- about 20 percent of those diagnosed with high blood pressure -- as if the sudden rise posed a threat.

However, a 10-year study of people with white-coat hypertension in Britain, published in today's Circulation: Journal of the American Heart Association, indicates the condition may not always be worth so much worry.

"One clinical implication of this study is that the cost of performing 24-hour blood pressure monitoring can be offset by the savings of avoiding unnecessary drug treatment in patients diagnosed with white-coat hypertension," says Thomas G. Pickering, M.D., professor of medicine, New York Presbyterian Hospital, New York City. His editorial appears in today's Circulation: Journal of the American Heart Association.

Pickering adds that, typically, 24-hour monitoring costs between $100 and $200, depending on where the procedure is done.

"Some people who have white-coat hypertension do develop sustained hypertension later on," says the study's senior author, Avijit Lahiri, M.B., M.Sc., of the department of cardiovascular medicine at Northwick Park Hospital, Middlesex, U.K. "However, it is difficult to tell which of them will develop hypertension. Using non-invasive blood pressure monitoring currently available to us is accurate and cost-efficient."

Researchers say people with white-coat hypertension had about half the number of heart attacks, deaths from cardiovascular disease or need for treatment for heart disease than individuals with sustained high blood pressure. In addition, those who had sustained high blood pressure had four times the risk of stroke compared to the group with white-coat hypertension.

In the study, 479 people diagnosed with high blood pressure were equipped with invasive 24-hour blood pressure monitors. The technique for this test to measure blood pressure -- the intra-arterial method -- is used for research purposes only because of its accuracy.

A needle is inserted into a blood vessel in the arm and taped to the arm while patients go about their daily routine. The blood pressure generated by every heartbeat for 24 hours is recorded by a tiny tape recorder. Lahiri says this method is the most accurate way to measure blood pressure. It is not used regularly, however, because it is a very invasive technique, says Lahiri. He adds that the standard ambulatory-cuff method can provide similar information and can be used daily in practice.

Lahiri says this is the first use of the intra-arterial method to study specifically white-coat hypertension. People were considered white-coat hypertensive if their systolic (top number) blood pressure was measured between 140-180 millimeters of mercury (mm/Hg), and was reduced to more normal levels outside the clinic. Lahiri says research shows that systolic blood pressure can be a strong predictor of future cardiovascular disease.

Of the 479 people in the study, 126 patients had white-coat hypertension. The others, whose blood pressure was not significantly reduced outside the doctor's office, were categorized as having mild sustained high blood pressure.

After nine years of follow-up, Lahiri and his colleagues report that four of the white-coat hypertension group died of non-cardiovascular events, five died of heart attacks, three survived heart attacks, and three needed revascularization, or surgery to restore blood flow to the heart. This equates to an "event rate" of 1.32 events per 100 patient-years.

The group with sustained hypertension fared worse. Eighty-three had some type of major cardiovascular disease, including 16 heart attack deaths, 10 strokes, 31 heart attacks, and 13 revascularizations -- an "event rate" more than double the white-coat hypertension group at 2.56 events per 100 patient-years.

"There is evidence that 24-hour blood pressure monitoring is not only superior in selecting patients for treatment but also in assessing the effects of treatment," says Pickering. "It is unfortunate that this procedure is still not recognized for reimbursement by Medicare and most other payers despite the fact that its clinical utility has been recognized."

Physicians first discovered the problem of white-coat hypertension about 1940, when many patients diagnosed with high blood pressure went home, tested themselves, and found their blood pressure was normal. Patients apparently became anxious in the clinic or doctor's office. It was assumed that the temporary rise in blood pressure was an omen for more serious problems later.

Co-authors are Rajdeep S. Khattar, B.M., and Roxy Senior, M.D.

American Heart Association

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