Medical professionals have long known that blood pressure measured in a doctor's office may not reflect your actual normal blood pressure. This could be due to one of two conditions that cause 'false' readings, and recent research shows that both require more consistent and accurate blood pressure monitoring.
When the stress and anxiety caused by a visit to a clinic or hospital lead to blood pressure readings that are higher than normal, the effect is known as white coat hypertension (WCH) or "white coat syndrome," named after the coats that doctors wear. WCH affects about one in five people. It is not necessarily a response to the presence of a doctor or nurse; the fear that some people have before and during a doctor's visit can cause the syndrome.
The second condition, known as "masked hypertension," is the opposite of WCH. Masked hypertension occurs when people normally have high blood pressure, but it does not show up when measured at the doctor's office.
WCH can lead to inappropriate misdiagnosis of high blood pressure (hypertension) and overmedication. It may also indicate that the person's blood pressure tends to rise if he or she has anxiety for other reasons. Masked hypertension, on the other hand, can prevent the necessary treatment of high blood pressure.
Changes in guidelines
Suzanne Oparil, MD, director of the UAB Medicine Vascular Biology and Hypertension Program, says WCH has become an increasingly important topic since 2017, the year the American College of Cardiology and the American Heart Association (ACC/AHA) jointly released new guidelines that lowered blood pressure. the definition of high blood pressure from 140/90 to 130/80 (120/80 or less is considered normal). Dr. Oparil says the guidelines raise concerns that healthcare providers are not considering WCH as often as they should.
“To get an accurate blood pressure reading, a patient should be in a quiet area, sitting with both feet on the floor, for at least five minutes,” says Dr. Oparil. “But we have seen in many clinical settings that patients are rushed through the visit. They sit down for an immediate blood pressure reading while being asked questions about medications, their health history, marital status and other matters. Most patients are already concerned about it , which brought them to the clinic in the first place, and immediately they have the added mental task of trying to answer questions correctly. The resulting anxiety can increase blood pressure by 10 points or more."
Studies have shown that clinics rarely perform two or more blood pressure measurements, even though the ACC/AHA guidelines suggest this may reduce the effects of WCH. There is no method to eliminate WCH, but measuring blood pressure several times at home or at work and comparing these results with clinical measurements may at least indicate that the person has the syndrome. Studies also suggest that a subgroup of people who experience WCH may be at greater risk of actually developing high blood pressure. Therefore, it is important to identify and monitor people with the condition and check your blood pressure regularly when you are resting.
Paul Muntner, PhD, professor of epidemiology at the UAB School of Public Health, led a study on this question and published the results in 2019. It shows that nearly 93% of adults in the United States who present with elevated blood pressure when they consult their doctor is measured in the office but not taking blood pressure medications, should be screened for WCH.
The researchers also found that many adults suffer from masked hypertension.
“For some people, a doctor's office is a place where they are relaxed,” Muntner says. “They are far away from work stress, traffic and family problems. Masked hypertension is associated with a high risk of heart disease and stroke. That is why it is important that people have their blood pressure measured correctly so that they can be diagnosed with hypertension and started on medication to lower their blood pressure.”
Home test
The blood pressure monitors in pharmacies and supermarkets may not be accurate. The AHA recommends measuring blood pressure at home with a device with an accuracy-controlled upper arm cuff. Cheap home versions can be purchased online and at pharmacies. Patients should discuss with their doctor which devices work best and exactly how to use them. Blood pressure should be measured twice in the morning and twice in the evening for a week. Devices that record measurements eliminate the need to write down the results.
Muntner says accurate measurements are important for getting the right treatment.
“Blood pressure monitoring at home will better inform both doctors and patients,” he says. “This means that doctors do not start patients on medication if they do not have high blood pressure. It also ensures that doctors initiate treatment for patients who have high blood pressure or are at risk of cardiovascular disease.”
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