Study puts the squeeze on vascular disease
Pressure check Next time you go to your GP to get your blood pressure checked, roll up both your sleeves.
UK researchers have found differences in systolic blood pressure between your left and right arm could be an early sign of increased risk of vascular disease.
The study, led by Dr Christopher Clark from the University of Exeter in the United Kingdom, urges doctors to routinely measure blood pressure simultaneously in both arms.
They say this simple measure, which has been recommended for some time but not often used, can detect narrowing and hardening of the blood vessels that supply the legs and feet — a condition known as peripheral vascular disease or peripheral artery disease.
Peripheral vascular disease, which is difficult to detect, is a risk factor for heart disease, stroke and death.
"Early identification of peripheral vascular disease allows interventions to be given and might improve outcomes," they write in The Lancet .
The researchers reviewed 28 studies assessing the link between differences in systolic blood pressure between the left and right arms and heart, stroke and vascular disease and death.
They found that a difference of 10 mm Hg or more or 15 mm Hg or more between the two arms is associated with an increased risk of having peripheral vascular disease.
A difference of 15 mm Hg or more was also associated with an increased risk of narrowing and hardening of the arteries in the brain, increasing the risk of cerebrovascular accidents, and an increased risk of heart attacks and death.
"Our findings suggest that a difference in systolic blood pressure of a10 mm Hg or more between arms could identify patients at high risk of asymptomatic peripheral vascular disease and mortality who might benefit from further assessment," the authors write.
While more research is needed to clarify whether substantial differences between arms should prompt aggressive management of cardiovascular risk factors, the review supports clinical guidelines stating that blood pressure should be measured in both arms, says Professor Richard J McManus from the University of Oxford and Professor Jonathan Mant from the University of Cambridge.
"[The study] supports existing guidelines stating that blood pressure should be measured in both arms. Ascertainment of differences should become part of routine care, as opposed to a guideline recommendation that is mostly ignored," they write in a commentary in The Lancet.
Australian clinical guidelines recommend that doctors measure both arms, at least the first time someone goes to the doctor for a check-up, says Professor Garry Jennings, director of the Baker IDI Heart and Diabetes Institute.
"It's there but we've not taken much notice of how that ought to be done," says Jennings.
"In particular I think most doctors measure it in one arm and take the cuff off and measure it in the other arm, but this study suggests that it's not as accurate in defining the importance of this difference as measuring it in both arms simultaneously."
He says it is important to measure the arms at the same time to eliminate errors from factors such as changes in blood pressure due to natural variations of blood pressure over time, or 'white coat hypertension', where some people's blood pressure rises due to anxiety of having their reading taken.
"Therefore we should be thinking about whether we should all have two blood pressure machines in our clinics as opposed to just one," he says.
Even though the majority of the studies reviewed were conducted on people with existing cardiovascular conditions, Jennings says the findings are relevant to the general population.
"We know from community studies that peripheral vascular disease is really very common, and the reason it's important is because atherosclerosis, which is the underlying cause [of peripheral vascular disease], is a condition which doesn't affect one part of the body."
He says differences in blood pressure in the subclavian arteries — the arteries that supply blood to the arms — can indicate blockages caused by atherosclerosis, which is likely to be in other vessels.
"So [measuring both arms simultaneously] is a very good way of evaluating someone who needs rather more aggressive preventive treatment whether it's with lifestyle or drugs, or usually both."