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Cuff-measured BP varies in accuracy
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Cuff BP measurements may be less accurate than intra-arterial brachial systolic BP and intra-arterial diastolic BP, according to a meta-analysis of studies from the past 60 years.
“Relatively small errors in cuff BP measurement can have major public health ramifications,” Dean S. Picone, BMedRes(Hon), of the Menzies Institute for Medical Research at the University of Tasmania in Australia, and colleagues wrote. “An inaccuracy of 5 mm Hg is estimated to result in the misclassification of BP of 48 million people each year in the United States alone (21 million underestimated BP, 27 million overestimated BP). BP underestimation leads to missed therapeutic potential and unnecessary elevation of cardiovascular risk.”
The researchers analyzed data from 74 studies from the 1950s to 2016, with 3,073 participants included.
Picone and colleagues found that intra-arterial brachial systolic BP was higher than aortic values (8 mm Hg; 95% CI, 5.9-10.1) and intra-arterial brachial diastolic BP was lower than aortic values (–1 mm Hg; 95% CI, –2 to –0.1).
Cuff BP overestimated intra-arterial diastolic BP (5.5 mm Hg; 95% CI, 3.5-7.5) and underestimated intra-arterial brachial systolic BP (–5.7 mm Hg; 95% CI, –8 to –3.5 mm Hg). There was a small mean difference between cuff and intra-arterial aortic systolic BP (0.3 mm Hg; 95% CI, –1.5 to 2.1). However, there was poor agreement with mean absolute difference of 8 mm Hg (95% CI, 7.1-8.9).
Agreement between BP classification using cuff BP compared with intra-arterial brachial BP was 60% for normal BP, 50% for prehypertension, 53% for hypertension stage 1 and 80% for hypertension stage 2. Classification agreement using cuff BP vs. intra-arterial aortic BP was 79% for normal, 57% for prehypertension, 52% for hypertension stage 1 and 76% for hypertension stage 2.
“A key problem in addressing the global burden of disease related to high BP is improving the diagnosis and characterization of the hypertensive phenotype,” the researchers wrote. “A fundamental problem with BP accuracy was identified in our study that affects most (but not all) cuff BP devices. Despite strong correlations between cuff BP and intra-arterial BP, 16 of 22 examined cuff BP devices significantly underestimated intra-arterial brachial [systolic] BP and 15 of 18 significantly underestimated [pulse pressure].”
In an accompanying editorial, George S. Stergiou, MD, PhD, associate professor of medicine and hypertension in the Third University Department of Medicine at Sotiria Hospital in Athens, Greece, and colleagues wrote: “Whether the more accurate measurement of brachial BP or the implementation of accurate aortic (central) BP measurement in clinical practice can contribute to more efficient prevention of [CVD] are challenging research questions. To allow these questions to be addressed, novel noninvasive technologies that provide such measurements in static and dynamic conditions need to be developed and properly validated.” – by Cassie Homer
Disclosures: Picone and Stergiou report no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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