Whenever you visit your doctor's office, you probably have come to expect a blood-pressure check by a nurse before you are seen by your physician. But chances are one in three that these routine blood-pressure readings are wrong, according to a recent UC Irvine study.
UCI researchers have found that a third of the people diagnosed as having high blood pressure don't actually have it. And an equal percentage with supposedly normal readings were found to have high blood pressure and not know it.
Since one in four Americans--60 million people, according to estimates by the American Heart Assn.--suffer from potentially fatal hypertension (high blood pressure), the study has far-reaching implications, according to lead researcher Dr. Michael Weber, 43, a UCI professor of medicine who is the director of the Long Beach-based Hypertension Center.
(Hypertension and high blood pressure are used interchangeably by physicians and, according to Weber, the terms mean the same thing: the actual force or pressure of blood within the heart and arteries is too high. In time this can lead to other medical emergencies, such as strokes, heart attacks or kidney disease.)
The UCI study, which looked at the effectiveness of 24-hour monitoring of blood pressure, was published this summer in the American Heart Journal. It used a high-tech monitoring device originally developed to study blood-pressure fluctuations in space shuttle astronauts.
"We have been working with the device since 1978, when (physician-engineer-astronaut) Bill Thornton, who was the first person to wear it in space, came here to the Hypertension Center and finished the final design so that it could be used on patients here on Earth," Weber said.
The instrument, Pressurometer III, is now manufactured by Del Mar Avionics of Irvine and uses a conventional blood-pressure cuff worn on the arm. It attaches to a four-pound recording device that can be worn on a belt or with a shoulder harness. The device automatically inflates the cuff at regular intervals, taking blood-pressure readings and recording them as the patient carries out his everyday tasks over a 24-hour period.
Subjects 'Perfectly Matched'
In earlier studies, Weber and his associates had used the device to study hundreds of people with hypertension and more than 80 people with normal blood pressures. However, Weber said this latest study was the first ever conducted in the United States in which patients with high blood pressure and patients with normal blood pressure were studied at the same time using the 24-hour monitoring device. He said the study's subjects "were perfectly matched" for age, height and weight to remove any variables that might affect blood-pressure readings.
During the study, Weber and his colleagues monitored 29 men who previously had been diagnosed as having hypertension and another 29 male volunteers who previously had been diagnosed as having normal blood pressure. Weber's research team discovered that nine of the hypertensive patients had fewer than 25% of their readings in the high-blood-pressure range.
On the other hand, an equal number of supposedly healthy men were found to have more than 25% of their readings in the high-blood-pressure range.
If those percentages were extrapolated to the general population, Weber said, it would mean that millions of Americans are needlessly being prescribed anti-hypertensive medications, which sometimes cause negative side effects, such as dizziness, depression and impaired alertness.
"And of course there is the unnecessary expense and inconvenience of taking this medication," Weber said during a recent interview in his office at the Hypertension Center, a research and treatment facility operated jointly by UCI and the Veterans Administration Medical Center in Long Beach.
Many Not Treated
Equally alarming, Weber said, is that more than 30% of supposedly healthy people may actually suffer from hypertension but are not being treated for the disease, which is a leading cause of heart attacks and strokes in the United States and a major cause of death in people over 50.
Weber said that he and fellow researchers Dr. Jan Drayer, a UCI professor of medicine, and research associate Dina Nakamura found that the 24-hour monitoring procedure overcomes the problems of one-time tests in doctors' offices because of the continuous recording feature.
"Twenty-four-hour monitoring eliminates the effects of apprehension and stress some patients experience when they are tested in a doctor's office, causing them to have abnormally high blood-pressure readings," Weber said.
More important than documenting the failings of the present one-time method of measuring blood pressure, Weber said, is the fact that the UCI study is "going to improve the quality of treatment for high blood pressure."
'More Confident Diagnoses'