Research makes case for home blood pressure monitoring

A lot of people have normal readings at doctors' offices, but elevated blood pressure at work or home. Home blood pressure monitoring can help identify these people, studies show.

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Think you've got normal blood pressure because the readings are always good at the doc's? Think again. As many as one in seven of us have what is called "masked hypertension" -- meaning we have healthy blood pressure readings in the comfort of our doctors' offices, but elevated blood pressure at work or home.

New research of more than 5,000 people spanning four countries finds that not only do people with this kind of hidden hypertension have a greater risk of heart attacks and strokes, but that home blood pressure monitoring often helps identify this phenomenon.

The reasons for this kind of hypertension have yet to be pinned down with great confidence, but daily life stressors and certain behaviors like alcohol and contraceptive use are thought to be culprits. And while home blood pressure monitoring has already been touted as a great way to help people manage high blood pressure, the new findings make the case that more widespread home monitoring could actually help diagnose it as well.

Dr. Jan Staessen, a cardiovascular diseases researcher at the University of Leuven in Belguim and senior author of the studies published in the journals PLOS Medicine and Hypertension, found in an analysis that of the people he studied with masked hypertension, 5 percent had "optimal" readings (120-80) at the clinic, 18.4 percent had "normal" clinic readings (120-129/80-84), and 30.4 percent had "high-normal" (130-139/85-59). (Mild hypertension was considered to be 140-159/90-99, while severe hypertension was 160+/100+.)

"We know that a lot of cardiovascular complications occur in people who are normotensive if you measure the blood pressure in the regular way in the office," Staessen told Reuters Health.

So in his other study, Staessen wanted to learn precisely how home monitoring affects the heart disease risks of patients with either masked or "white coat" hypertension -- which is the opposite problem, where readings are high at the doc's office but low at home. (The white coats and clinics presumably elevate blood pressure in these patients.) To do this, he looked at the readings of 6,458 people, 5,007 of whom were not being treated for any blood pressure problems. Of that group, 404 had masked hypertension while 695 had white-coat hypertension.

Staessen found that masked hypertension raised one's risk for heart attack and stroke by 55 percent when compared to people with normal blood pressure, while white-coat hypertension raised the risk by 42 percent. Even when compared to patients being treated for high blood pressure, masked hypertension that was diagnosed via home monitoring raised the risk by 76 percent -- likely because this type of hypertension involves, by its very definition, undertreatment.

Straessen adds that even regardless of diagnosis, those with risk factors for masked hypertension -- smokers, the obese, the elderly -- should regularly monitor their blood pressure at home to get a more accurate blood pressure picture.

Meanwhile, Dr. Mark Caulfield of Barts and The London School of Medicine and Dentistry writes in a PLOS Medicine editorial that, with both the growing "burden" of high blood pressure and the availability of affordable home monitoring devices, home blood pressure monitoring should take on an expanded role: "Home blood pressure monitoring could be used to diagnose high blood pressure and help decide whom to treat. It empowers patients to take on a role in assessment of their blood pressure."

With cardiovascular diseases being the leading cause of death worldwide, according to the World Health Organization, finding, treating, and of course preventing one of its leading risk factors, hypertension, could add up to a lot of saved lives and health care dollars.