Faulty blood pressure readings may lead to inflated diagnosis, study finds
In order to get the most accurate reading, patients should have their feet flat on the floor, legs uncrossed and an arm stabilized at mid-heart level. A Wantagh woman has her blood pressure checked before donating blood in 2010. Credit: John Dunn
Blood pressure tests taken when a patient's arm is not positioned properly could lead to inaccurate readings and false hypertension diagnoses, according to a new study released Monday.
Taking a blood pressure reading on someone whose arm hangs at their side or is supported on their lap rather than being on a table could boost their numbers, according to researchers at the Johns Hopkins University School of Medicine and its Bloomberg School of Public Health.
Researchers concluded that improper arm position could result in 16% to 22% of adults in the U.S. — 40 to 54 million people — being misclassified as having hypertension, depending on which threshold is used to determine if someone has the disease.
"Incorrect positioning of a patient's arm when taking blood pressure measurements may significantly overestimate their blood pressure and lead to unnecessary treatment," Dr. Eugene Yang, a professor of cardiology and medicine at the University of Washington School of Medicine and a member of a hypertension committee with the American Heart Association wrote in an email. He was not involved in the study.
"It is vital that both patients and clinicians are educated on all aspects of blood pressure measurement, including correct cuff sizing and arm positioning, to minimize inaccurate blood pressure readings," he wrote.
Accurate readings are especially important since some health care providers use a lower threshold for hypertension of 130 over 80, which has been recommended by the heart association and the American College of Cardiology. Other clinicians still use 140 over 90 as the mark where hypertension starts.
"I personally think that there's a lot of people who may not have high blood pressure who are being diagnosed as having high blood pressure," said Dr. Benjamin Hirsch, a cardiologist and director of preventive cardiology at North Shore University Hospital.
"There’s been a lot of emphasis on treatment targets being lower, but the guidelines also talked about how to take blood pressure and a lot of people have not paid attention to that," said Hirsch. "But it really matters how you take the blood pressure, it’s really kind of a critical part of the story."
Blood pressure readings are a common and vital part of most medical visits. People with high blood pressure are at a higher risk for heart disease and stroke. These readings determine the pressure of blood pushing against the walls of arteries that move blood from the heart to other parts of the body, according to the Centers for Disease Control and Prevention.
These arteries can be damaged by high blood pressure, which can decrease blood and oxygen flow to the heart.
The heart association said about half the adults in the United States have high blood pressure but many don’t know they have it. Once diagnosed, it can be controlled with medication as well as a healthy diet and exercise regimen.
In order to get the most accurate reading, patients should have their feet flat on the floor, legs uncrossed and an arm stabilized at mid-heart level, according to the heart association.
The study took 133 adults between the ages of 18 and 80, put them into six groups where they would have their blood pressure measured in the three arm positions — hanging from their side, in their lap and on a desk — in different order on a digital blood pressure device. Finally, they had it done a fourth time with their arm on a desk.
When the participants’ arms were supported on their lap, the systolic BP, or the top number in a reading, was overestimated by 3.9. Systolic measures the force of blood flow when it is pumped from the heart. Diastolic pressure, which measures the pressure on the arteries when the heart rests between beats, was higher by 4.0 when compared with the recommended position of an arm on a table. That makes up the bottom number of a reading.
Blood pressure taken on a person whose arm was not supported at all showed 6.5 overestimation systolic and 4.4 for diastolic when compared with measures taken with their arm on the table.
Researchers pointed out their study was done using automated blood pressure devices and might differ from those taken with other devices.
Dr. Tammy Brady, senior author of the study and medical director of the pediatric hypertension program at the Johns Hopkins Children's Center, noted that studies show health care providers don’t always take the steps necessary to get the most accurate blood pressure reading.
“My hope is that this study alerts health care providers and patients alike to the importance of arm position and support on BP measurement – it's more than just putting on a cuff and pushing a button,” Brady said in an email.
She said she hopes patients will feel “empowered” to ask for a repeat blood pressure measurement in ideal conditions – which includes an arm supported with mid-cuff at heart level – if their reading is ever elevated.
Blood pressure tests taken when a patient's arm is not positioned properly could lead to inaccurate readings and false hypertension diagnoses, according to a new study released Monday.
Taking a blood pressure reading on someone whose arm hangs at their side or is supported on their lap rather than being on a table could boost their numbers, according to researchers at the Johns Hopkins University School of Medicine and its Bloomberg School of Public Health.
Researchers concluded that improper arm position could result in 16% to 22% of adults in the U.S. — 40 to 54 million people — being misclassified as having hypertension, depending on which threshold is used to determine if someone has the disease.
"Incorrect positioning of a patient's arm when taking blood pressure measurements may significantly overestimate their blood pressure and lead to unnecessary treatment," Dr. Eugene Yang, a professor of cardiology and medicine at the University of Washington School of Medicine and a member of a hypertension committee with the American Heart Association wrote in an email. He was not involved in the study.
"It is vital that both patients and clinicians are educated on all aspects of blood pressure measurement, including correct cuff sizing and arm positioning, to minimize inaccurate blood pressure readings," he wrote.
Accurate readings are especially important since some health care providers use a lower threshold for hypertension of 130 over 80, which has been recommended by the heart association and the American College of Cardiology. Other clinicians still use 140 over 90 as the mark where hypertension starts.
"I personally think that there's a lot of people who may not have high blood pressure who are being diagnosed as having high blood pressure," said Dr. Benjamin Hirsch, a cardiologist and director of preventive cardiology at North Shore University Hospital.
"There’s been a lot of emphasis on treatment targets being lower, but the guidelines also talked about how to take blood pressure and a lot of people have not paid attention to that," said Hirsch. "But it really matters how you take the blood pressure, it’s really kind of a critical part of the story."
Blood pressure readings are a common and vital part of most medical visits. People with high blood pressure are at a higher risk for heart disease and stroke. These readings determine the pressure of blood pushing against the walls of arteries that move blood from the heart to other parts of the body, according to the Centers for Disease Control and Prevention.
These arteries can be damaged by high blood pressure, which can decrease blood and oxygen flow to the heart.
The heart association said about half the adults in the United States have high blood pressure but many don’t know they have it. Once diagnosed, it can be controlled with medication as well as a healthy diet and exercise regimen.
In order to get the most accurate reading, patients should have their feet flat on the floor, legs uncrossed and an arm stabilized at mid-heart level, according to the heart association.
The study took 133 adults between the ages of 18 and 80, put them into six groups where they would have their blood pressure measured in the three arm positions — hanging from their side, in their lap and on a desk — in different order on a digital blood pressure device. Finally, they had it done a fourth time with their arm on a desk.
When the participants’ arms were supported on their lap, the systolic BP, or the top number in a reading, was overestimated by 3.9. Systolic measures the force of blood flow when it is pumped from the heart. Diastolic pressure, which measures the pressure on the arteries when the heart rests between beats, was higher by 4.0 when compared with the recommended position of an arm on a table. That makes up the bottom number of a reading.
Blood pressure taken on a person whose arm was not supported at all showed 6.5 overestimation systolic and 4.4 for diastolic when compared with measures taken with their arm on the table.
Researchers pointed out their study was done using automated blood pressure devices and might differ from those taken with other devices.
Dr. Tammy Brady, senior author of the study and medical director of the pediatric hypertension program at the Johns Hopkins Children's Center, noted that studies show health care providers don’t always take the steps necessary to get the most accurate blood pressure reading.
“My hope is that this study alerts health care providers and patients alike to the importance of arm position and support on BP measurement – it's more than just putting on a cuff and pushing a button,” Brady said in an email.
She said she hopes patients will feel “empowered” to ask for a repeat blood pressure measurement in ideal conditions – which includes an arm supported with mid-cuff at heart level – if their reading is ever elevated.
Lisa joined Newsday as a staff writer in 2019. She previously worked at amNewYork, the New York Daily News and the Asbury Park Press covering politics, government and general assignment.
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Newsday Live Music Series: Long Island Idols Newsday Live presents a special evening of music and conversation with local singers who grabbed the national spotlight on shows like "The Voice," "America's Got Talent,""The X-Factor" and "American Idol." Newsday Senior Lifestyle Host Elisa DiStefano leads a discussion and audience Q&A as the singers discuss their TV experiences, careers and perform original songs.
