A difference of 15 mm Hg or more in systolic blood pressure between a patient’s arms may signal the presence of asymptomatic peripheral vascular disease, according to a meta-analysis published online Jan. 30 in the Lancet.
Patients with this finding on physical examination might benefit from further assessment for peripheral vascular disease, much as those found to have reduced ankle-brachial pressure do. But simultaneous measurement of systolic BP in both arms is more easily done in the primary care setting, since such measurement in one arm is already routine and doesn’t require the time, experience, and training necessary for ankle-brachial pressure assessment, said Dr. Christopher E. Clark of the institute of health services research, University of Exeter (England), and his associates.
©Dr. Heinz Linke/iStockphoto.com
A meta-analysis showed that systolic blood pressure difference between a patient’s arms could mean there is asymptomatic peripheral vascular disease.
The most recent National Institute for Health and Clinical Excellence (NICE) guideline for hypertension states that a difference of 20 mm Hg or more between the arms is "unusual" and is often associated with underlying vascular disease, but doesn’t address smaller differences. The guideline also has advised routinely checking BP in both arms for several years, but most primary care physicians in the United Kingdom do not follow that advice, Dr. Clark and his colleagues said.
To establish whether small differences (10-15 mm Hg) in systolic blood pressure between the arms is associated with peripheral or cardiovascular disease, they performed a meta-analysis of 20 studies addressing the issue.
The investigators found that a difference of 10-15 mm Hg occurred in 12%-15% of the study subjects and was associated with peripheral vascular disease, with a low sensitivity but a very high specificity. This overall prevalence corresponds to published estimates in community studies, implying that findings of the meta-analysis are generalizable, they noted.
In particular, five studies that correlated systolic BP with findings on invasive angiography showed that a difference of 10 mm Hg or more was strongly associated with subclavian stenosis on the side with the lowest pressure (Lancet 2012 Jan. 30 [doi:10.1016/S0140-6736(11)61710-8]).
In pooled findings from studies with noninvasive assessments of vascular disease, a difference of 15 mm Hg or more was associated with not only peripheral vascular disease (sensitivity of 15% and specificity of 96%), but also with cerebrovascular disease (sensitivity of 8% and specificity of 93%) as well as increased cardiovascular and all-cause mortality.
In five studies, a difference as low as 10 mm Hg was associated with peripheral vascular disease (sensitivity of 32% and specificity of 91%).
These findings remained consistent across studies that used different methods of measuring BP, regardless of whether the cohorts comprised high-risk hospital-recruited patients or average-risk people living in the community.
Because this study was a meta-analysis rather than a randomized clinical trial, "what constitutes a clinically important difference in systolic BP between arms is [still] unclear. However, we have associated a difference with an increased likelihood of peripheral vascular disease and with prospective differences in survival. Further research is needed to establish the upper limit of normal between-arm differences," Dr. Clark and his associates wrote.
In an editorial accompanying this report, Dr. Richard J. McManus and Dr. Jonathan Mant wrote: "The high specificity (96%) of the association between a difference in systolic BP between arms of more than 15 mm Hg and peripheral vascular disease justifies the use of this measure as a sign of disease" (Lancet 2012 Jan. 30 [doi:10.1016/S0140-6736(11)61926-0]).
Ascertaining such differences should become part of routine care, "as opposed to a guideline recommendation that is mostly ignored," said Dr. McManus of the department of primary care health sciences at the University of Oxford (England) and Dr. Mant of the department of public health and primary care at the University of Cambridge (England).
However, "the low sensitivity (15%) shows that measurement of differences is of little value as a screening test for peripheral vascular disease, and ankle-brachial pressure indices will still be necessary for diagnosis," they noted.
Neither Dr. McManus nor Dr. Mant reported having any relevant financial disclosures.
This study was funded by the Royal College of General Practitioners, the South West GP Trust, and the Peninsula Collaboration for Leadership in Applied Health Research and Care. The investigators reported that they had no relevant financial disclosures.