BP differences between arms linked to vascular disease, death

Differing Arm Blood Pressure Linked to Vascular Disease, Death
Differing Arm Blood Pressure Linked to Vascular Disease, Death

HealthDay News -- Systolic blood pressure (BP) that differs more than 10 or 15 mm Hg between arms is associated with higher overall cardiovascular (CV) and mortality risks, results of a metaanalysis indicate.

Christopher E. Clark, PhD, from the University of Exeter in the United Kingdom, and colleagues reviewed 28 studies on the association of differences in systolic BP between arms and vascular diseases, subclavian stenosis and survival, of which 20 reported quantitative data used in the analysis. 

Differences in systolic BP of 15 mm Hg or more between arms resulted in a 70% increased risk for death from CV causes (P=0.01) and a 60% higher likelihood of dying from any cause (P=0.02), the researchers reported online in Lancet.

The between-arm BP difference appears to be strongly correlated with peripheral artery disease (PAD; 96% specificity) and cerebrovascular disease (93% specificity), the researchers noted. 

Pooled analysis revealed that patients  with a 15 mm Hg or more difference had a higher risk of pre-existing cerebrovascular disease (risk ratio=1.6; 95% CI: 1.1-2.4), CV mortality (hazard ratio=1.7; 95% CI: 1.1-2.5) and all-cause mortality (HR=1.6; 95% CI: 1.1-2.3).

Differences of 10 mm HG or 15 mm Hg or more "might help to identify patients who need further vascular assessment," the researchers suggested and that a difference of 15 mm Hg or more "could be a useful indicator of risk for vascular disease and death."

Patients with a difference of 10 mm Hg (RR=2.4; P=0.0002) or 15 mm Hg or more (RR=2.5; P<0.0001), were more than twice as likely to have PAD and had a greater than eight-fold increase in risk for subclavian stenosis (RR=8.8; P<0.0001; 65% sensitivity and 85% specificity).

Measuring BP in both arms should become routine practice, Richard J. McManus, MSc, MBBS, of the University of Oxford and Jonathan Mant, MD, of the University of Cambridge, both in the UK, recommended in an accompanying editorial.

However, PAD is  clinically silent and measuring ankle-brachial pressure index (the gold standard for detecting PAD) takes time and training, so it is not often performed in primary care, they noted noted. But detecting the disease early could encourage clinicians to "promote smoking cessation, lower [BP] or offer statin therapy to  reduce mortality."Using a specialized sphygmomanometer available in most clinics and a spare digital BP monitor to measure the other arm's BP simultaneously could help avoid a potential white-coat hypertension effect, McManus and Mant suggested.

More studies are needed to determine the specific upper limit of BP differences between arms and to better define clinically important differences, the researchers noted. 

Limitations included study populations with elevated CV risk such as those with existing PAD, and those preparing to undergo cardiac surgery. About half of the studies involved primary care or community-based populations.

Clark CE. Lancet. 2012; doi: 10.1016/S0140-6736(11)61710-8.

McManus RJ, Mant J. Lancet. 2012; doi: 10.1016/S0140- 6736(11)61926-0.

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