A new study suggests doctors should always measure blood pressure in both arms. If they don't, they could be missing significant signs of heart disease.

English researchers reviewed data on blood pressure measurements and found even a fifteen point difference in systolic blood pressure between arms more than doubled the risk for a form of vascular disease.

They say different blood pressure readings in two arms could be a sign the arteries are narrowing or hardening on one side of the body.

There are guidelines suggesting doctors measure blood pressure in both arms -- but a survey found fewer than half of doctors make it a habit.

The study reviewed 28 papers covering difference in systolic blood pressure between arms. It found significant evidence to suggest that a difference of 15mm hg or more was associated with increased risk of: Peripheral Vascular Disease (PVD: the narrowing and hardening of the arteries that supply blood to the legs and feet: 2.5 times increased risk); Pre-existing Cerebrovascular Disease (affecting the blood supply to the brain and often associated with cognitive issues such as Vascular Dementia: 1.6 times increased risk); and both Cardiovascular Mortality (70% increased risk), and All-Cause Mortality (60% increased risk). The risk of PVD was also increased at a difference of 10mm hg or more. The arm with the higher pressure can vary between individuals and it is the difference that counts, not which arm is higher and which is lower.