Is the blood pressure in your right arm different from that in the left? If so, you are more prone to heart disease and stroke.

A new Lancet study, published on Monday, says differences in systolic blood pressure between arms could be a useful indicator of the likelihood of vascular risk and death. The findings bolster support to the calls for both-arm blood pressure checks to be performed as standard.

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 (the narrowing and hardening of the arteries that supply blood to the legs and feet — 2.5 times increased risk). The study also found pre-existing cerebrovascular disease (affecting the blood supply to the brain and often associated with cognitive issues such as dementia — 1.6 times increased risk) and mortality, both as a result of cardiovascular problems and generally — 60% increased risk. The risk of peripheral vascular disease was also increased at a difference of 10mm Hg or more.Dr Anoop Misra, chairman of Fortis’ Centre of Excellence for Diabetes, Metabolic Diseases and Endocrinology, said, “This is an interesting finding. Usually, we check the BP of a single arm. Only in case of diabetics, we check BP in both arms and legs. Usually, 30% of patients in India show a 10 mm Hg variation between the two arms. However, checking BP in both arms is a simple exercise, and can be followed.”

Cardio logist Dr K K Aggarwal, who is the president of Heart Care Foundation of India, said, “Whenever a patient visits us for the first time, we check the BP in all the four limbs. The BP of lower limb should ideally be more than the upper limb. If it is less than upper limb, it is indicative of blockages in leg arteries and if the BP difference in two arms is more than 15 mm Hg, it is indicative of blockages in the arm artery. Blockage in the arms is associated with blockages in the brain vessels and heart arteries.” Dr Christopher Clark from the University of Exeter Peninsula College of Medicine and Dentistry (PCMD), who led the Lancet study, said, “We set out to investigate whether there was an association between differences in systolic blood pressure between arms and vascular disease and mortality. Our findings indicate a strong association, and that differences of 10mm Hg or 15mm Hg or more might help to identify patients who are at risk and who need further vascular assessment.”

The authors note that early detection of PVD is important because interventions to promote smoking cessation, lower blood pressure or offer statin therapy can reduce mortality. Most cases, however, are clinically silent, and gold-standard non-invasive identification of this disease requires detection of a reduced ankle-brachial pressure index (ratio of BP in ankle to BP in arm) at rest or after a stress test.

This complex technique requires time, experience and training and is not routinely undertaken in primary-care assessment of hypertensive patients. “Thus, the findings of this new study further support the need for both-arm blood pressure checks to be the norm,” it adds.