Mainstream heart health groups are calling for greater attention to how patients measure their blood pressure amid concerns that millions of Americans may be misdiagnosed and mismedicated due to inaccurate blood pressure readings. Researchers at The Ohio State University, along with the American Heart Association (AHA) and the American College of Cardiology, have discovered an alarming amount of erroneous blood pressure data due to differences in where and how it is measured.
Accurate readings are obtained when the patient sits in a chair with their feet flat on the floor and their back supported, placing the arm with the blood pressure cuff on the floor at heart level. Researchers found that other methods - such as measuring while the patient is lying on the exam table - inflated the numbers, resulting in higher readings. "This is not conducive to accurate blood pressure measurement," said researcher Dr. Randy Wexler, a general practitioner at The Ohio State University Wexner Medical Center in Columbus.
In the study, 150 adults were divided into three groups: One group had their blood pressure measured on a fixed-height examination table and then in a supported, adjustable chair; another group had the same test but in reverse order; and a third group had their blood pressure measured twice while in a chair.
Analysis of the pooled data found that readings measured on the examination table were much higher than when the same test was performed on an adjustable chair - with systolic blood pressure (the highest value) on average 7mmHg higher and diastolic blood pressure (the lowest value) on average 4.5mmHg higher.
Because of this, researchers believe that millions of people may be misdiagnosed as having high blood pressure, even though their blood pressure is actually within normal, healthy ranges. "We were not surprised by the difference. We were surprised by how big the difference was," Wexler said. This could lead to patients taking medications to control their blood pressure when they don't need to at all. In addition to side effects, drug treatments can cause patients to develop hypotension, which is a drop in blood pressure that is too low. This can lead to dizziness, lightheadedness, and fainting, which is especially serious for older adults who are at risk of falling.
"People may not need to take as many medications because of the side effects. That's why good and accurate blood pressure measurement becomes important," Wexler said.
Nearly half of U.S. adults have high blood pressure, which is diagnosed when systolic blood pressure reaches or exceeds 130 mmHg and diastolic blood pressure reaches or exceeds 80 mmHg.
The researchers also stressed that medical staff need to be given time to position patients correctly. They found that it takes primary care providers more than 26 hours a day to follow all the correct preventive and chronic disease care guidelines.
"We need to be more efficient," Wexler said. "But how do we make actionable changes without slowing down the patient care process?"
In the meantime, the researchers hope the study will also raise awareness for patients to follow simple measures such as keeping their feet flat on the ground, having their arms supported during the test and being careful not to talk during the assessment.
"We need to make sure that blood pressure is measured correctly and that blood pressure is treated correctly," said Dr. Jordana Cohen, a nephrologist at the Medical College of Pennsylvania in Philadelphia. "Health systems need to prioritize this. We have to convince them that it makes financial sense to do this because it will lead to better outcomes."
The findings were published in the journal eClinicalMedicine.