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Got High Blood Pressure? It Might Take 24 Hours To Know For Sure

The standard technique for measuring blood pressure may not be good enough.
The standard technique for measuring blood pressure may not be good enough.

A blood pressure check may well be the world's most common medical procedure. Measuring blood pressure is quick, painless, and provides a pretty good clue to risks for future heart attacks and strokes. But some researchers now say that the classic cuff test can be misleading.

Blood pressure readings at the doctor's office or at home give too many falsely high readings, according to a new report in The Lancet. As a result, too many people get put on medicine to lower blood pressure — as many as 25 percent of people may be on drugs unnecessarily, the researchers conclude.

So, as of today, the British government's National Institute for Health and Clinical Excellence now recommends that people who get a blood pressure reading of 140/90 millimeters of mercury (mmHg) or higher in the doctor's office get sent home with a mobile blood pressure monitor. The device straps around the waist and takes blood pressure readings for 24 hours.

The new testing regime, which the British institute calls "radical", is designed to overcome common errors in blood pressure testing. A person's blood pressure varies from hour to hour, and day to day.

What's more, many people suffer from " white-coat hypertension": their blood pressure soars when they see a doctor walk in the exam room in a white coat. To counter that, doctors often ask patients to come in three times to get their blood pressure checked before diagnosing hypertension.

Another common workaround is to ask a patient to check blood pressure at home. That should more accurately reflect a person's blood pressure in their regular environment. But the British researchers said that home testing is still not as accurate as ambulatory monitoring.

"What you're trying to prevent is multiple repeat visits to the clinician," Thomas Gaziano, a cardiologist at Brigham and Women's Hospital in Boston, told Shots. Each visit might cost $80 to $100, Gaziano says, which approaches the cost of ambulatory monitoring. "It's another way to confirm the diagnosis."

However, as Gaziano pointed out in a commentary he wrote for The Lancet, the British doctors were figuring that people would get ambulatory monitoring once every five years. If people end up needing it more often, that would increase costs.

The U.S. Preventive Services Task Force recommends that adults get their blood pressure checked every two years with a blood pressure cuff. People with a systolic pressure of 120 to 139 mmHg or diastolic blood pressure of 80 to 89 mmHg, should get checked every year.

The United States doesn't have one organization setting health standards, like the British. Gaziano says that the various boards will no doubt be considering expanding use of ambulatory monitoring, given the British decision.

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