Different blood pressure in each arm may be associated with increased risk for vascular disease

Patients who have significant differences in systolic blood pressure between their right and left arms may be at increased risk of vascular disease, a new study found.

The meta-analysis included 20 studies that compared blood pressure (BP) between patients' arms. Five studies used angiography and found that among patients with subclavian stenosis, the mean difference in systolic BP between arms was 36.9 mm Hg. In these invasively tested patients, a difference of 10 mm Hg or more was strongly associated with subclavian stenosis (risk ratio, 8.8). In the other, noninvasive studies included in the analysis, a difference of 10 mm Hg or more was associated with increased risk of peripheral vascular disease (risk ratio, 2.4; sensitivity, 32%; specificity, 91%).

When the cutoff for difference in systolic BP between arms was increased to 15 mm Hg, the analysis found patients who met that cutoff were more likely to have preexisting cerebrovascular disease (risk ratio, 1.6; sensitivity, 8%; specificity, 93%), cardiovascular mortality (hazard ratio, 1.7) and all-cause mortality (hazard ratio, 1.6). The findings were published online by The Lancet on Jan. 30.

The study authors concluded that a difference in systolic BP of 10 mm Hg or higher or 15 mm Hg or higher is associated with peripheral vascular disease, although with low sensitivity but high specificity, in both community- and hospital-recruited patient cohorts. This finding might be useful for identifying patients in need of further vascular assessment, they said, noting a cutoff of a 15 mm Hg difference would lead to further assessment for fewer than 5% of overall patients.

Although the study concluded that a 15 mm Hg difference could be a useful indicator of mortality risk, this finding was gathered from populations with a high baseline cardiovascular risk and so is not necessarily generalizable to lower-risk patients, the authors said. They recommended that these findings be incorporated into future guidelines but also be clarified by further research into normal versus excessive BP differences between arms.

A comment accompanying the study noted that international hypertension guidelines have already recommended measurement of BP in both arms. One obstacle to effective implementation is that patients are twice as likely to show differences between arms if their BP is measured sequentially rather than simultaneously. The commentary authors recommended measurement of BP in both arms, ideally simultaneously, to accurately diagnose hypertension, but they noted that the low sensitivity found in this study means that the practice has little value as a screening tool for peripheral vascular disease.