Why Blood Pressure Should Be Checked in Both Arms
Differences in blood pressure between a person’s arms can indicate increased health risks. A large new study not only confirms that fact but reveals that the bigger the difference, the greater the odds of a heart attack, stroke or other deadly cardiovascular event. Because doctors and nurses don’t always check both arms, feel free to ask them to.
Blood pressure, which indicates how hard the heart has to work, is measured by two numbers. The upper measure (systolic) marks the maximum pressure during the repeat pulses from the heart; the lower figure (diastolic) represents minimum pressure. When the top number exceeds 130 or the bottom number exceeds 80, a person is said to have hypertension, also called high blood pressure. Hypertension, often referred to as the “silent killer,” raises the risk of premature death from several afflictions, including heart disease, stroke and diabetes.
A 2014 study of 3,900 U.S. adults found those with at least a 10-point difference in the top number from one arm to the other were 38% more likely to have a heart attack or some other cardiovascular event during a 13-year period.
The new research, published December 21 in the journal Hypertension, involved a review of 24 separate global studies, merged to analyze data on 54,000 people in Europe, Africa, Asia and the United States across a decade. It showed that a 10-point interarm difference is a lower threshold indicating increased death from heart attacks and other cardiovascular issues.
Each point of additional difference between arms additionally raises risk by another 1%, the new study found. The scientists think the interarm difference indicates arteries are narrowed or stiffened, a condition linked to hypertension that is known to make blood flow more difficult and can lead to blockages that cut off blood supply to the heart, brain or other organs.
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“We’ve long known that a difference in blood pressure between the two arms is linked to poorer health outcomes,” said study leader Chris Clark, PhD, of the University of Exeter Medical School in England. “The large numbers involved [in the new study] help us to understand this in more detail. It tells us that the higher the difference in blood pressure between arms, the greater the cardiovascular risk, so it really is critical to measure both arms to establish which patients may be at significantly increased risk. Patients who require a blood-pressure check should now expect that it’s checked in both arms, at least once.”
Some 4% of people, in general, have interarm blood-pressure differences greater than 10 points, Clark and his colleagues say, as do 11% of people with hypertension. Guidelines that encourage physicians to check blood pressure in both arms are often ignored, the scientists note.
“Checking one arm then the other with a routinely used blood pressure monitor is cheap and can be carried out in any healthcare setting, without the need for additional or expensive equipment,” Clark said in a statement. “Whilst international guidelines currently recommend that this is done, it only happens around half of the time at best, usually due to time constraints. Our research shows that the little extra time it takes to measure both arms could ultimately save lives.”