Taking blood pressure measurements from both arms could help save lives, experts have said.
Scientists say they have found “robust evidence” that a difference in blood pressure between arms is linked to greater risk of death.
The findings, published in the journal Hypertension, are based on data gathered from 24 global studies of nearly 54,000 people.
Lead author and GP Dr Chris Clark, of the University of Exeter Medical School, said: “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.
“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.”
Dr Clark said that while health experts have long known that a difference in blood pressure between the two arms is linked to poorer health outcomes, their study helps to understand this association in greater detail.
He said: “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.”
Blood pressure is a measure of the force that the heart uses to pump blood around the body.
It is measured in units of millimetres of mercury (mmHg), and the reading is always given as two numbers: systolic pressure – the pressure when the heart pushes blood out, and diastolic pressure – the pressure when the heart rests between beats.
A significant difference between the systolic blood pressure measurements in the two arms is often a sign that arteries are narrowing or stiffening.
These changes in the arteries are seen as an indicator for subsequent heart attack, stroke or early death, the researchers said.
Both UK and European guidelines recognise a systolic difference of 15 mmHg or more between the two arms as the threshold to be associated with additional cardiovascular risk.
The researchers found that a lower threshold of 10 mmHg was clearly indicative of additional risk, which “would mean that far more people should be considered for treatment if such a difference between arms is present”.
Research co-author Professor Victor Aboyans, head of the department of cardiology at the Dupuytren University Hospital in Limoges, France, said: “We believe that a 10 mmHg difference can now reasonably be regarded as an upper limit of normal for systolic inter-arm blood pressure, when both arms are measured in sequence during routine clinical appointments.
“This information should be incorporated into future guidelines and clinical practice in assessing cardiovascular risk.
“It would mean many more people were considered for treatment that could reduce their risk of heart attack, stroke and death.”
It is thought that 11% of people with high blood pressure have an inter-arm difference of greater than 10 mmHg.
The research team said they have created a tool to establish who should be considered for treatment based on their risk, incorporating the blood pressure reading in both arms.
