Single Reading Can't Gauge Blood Pressure Control:
MONDAY, June 20 (HealthDay News) -- Evaluating how well a person
responds to medication meant to lower blood pressure requires
multiple readings, new research suggests.
Blood pressure often spikes at doctor appointments, a condition
known as "white coat" hypertension, so readings should also be
taken by patients at home, said the study's lead author, Dr.
Benjamin Powers, assistant professor of medicine at Duke University
''Collecting just a few, five or six, blood pressure readings from home will help your doctor make much better decisions about whether your blood pressure is in or out of control," Powers said.
For the study, Powers and his colleagues evaluated 444 U.S.
veterans with high blood pressure, about 90 percent of them men
with an average age of 64. All had been diagnosed about 10 years
earlier. Their blood pressure was considered uncontrolled, even
though most took multiple blood pressure-lowering medications.
Untreated, high blood pressure can lead to stroke.
The study compared blood pressure readings taken in three
settings -- at home, in a doctor's office, and at a clinical
research setting -- at the study start and again at 6, 12 and 18
months. The findings are published in the June 21 issue of the
Annals of Internal Medicine.
The measurements varied widely, Powers found. "Only a third of
them were consistently categorized as in or out of control by all
three measures," he said.
That points to the importance of getting multiple measures from
different settings, said Powers, who is also with the Durham
Veterans Affairs Medical Center. Using just one reading as the
basis for prescribing or adjusting blood pressure medication could
endanger patients who suffer from "white coat" hypertension, the
study authors said.
As many as six readings were needed to obtain the best estimate
of true blood pressure, the authors said, adding that doctors
should average the results.
Home monitoring of blood pressure has gained respect in recent
years, Powers said. About 43 percent of people with high blood
pressure use home monitors, according to background information in
the study. Powers and his colleagues said their results support
recent calls for reimbursement of home blood pressure
"I think patients should expect their doctors to make decisions based on home blood pressure [in addition to other measures]," he said.
Those who buy a home blood pressure monitor should get it
validated for accuracy at their doctor's office, Powers added.
Patients should be advised to measure their blood pressure at
different times of the day, and to sit and relax for five minutes
before taking it, Powers explained. Variations are to be expected,
According to Dr. Joseph Diamond, director of nuclear cardiology
at Long Island Jewish Medical Center in Hyde Park, N.Y., blood
pressure readings are perhaps "the most frequent assessment that
results in a change of medical therapy."
Even so, the procedure is frequently flawed because of poor
measurement technique or insufficient measurements, he said.
"This study confirms the need to improve both measurement technique and the number of measurements obtained so that a therapeutic decision to start or change medication is based on more accurate information," said Diamond.
Writing in an accompanying editorial of the journal, Dr.
Lawrence J. Appel and colleagues from Johns Hopkins University said
the findings point to a need for regulation of blood pressure
screening. "It is time to get serious about BP measurement," they
To learn more about home blood pressure monitoring, visit the
British Hypertension Society.
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