Inaccuracy of brachial blood pressure and its potential impact on treatment and aortic blood pressure estimation.

Abstract

Although brachial cuff SBP is universally used to guide hypertension management, it can differ significantly from intraarterial SBP. We examine the potential impacts of cuff-to-intraarterial brachial SBP (bSBP) mismatch on hypertension treatment and accuracy towards central SBP. In 303 individuals, cuff bSBP (CUFF-bSBP) and central SBP were measured using a Mobil-o-Graph simultaneously to intraarterial bSBP (IA-bSBP) and aortic SBP. According to the difference between CUFF-bSBP and IA-bSBP, we identified three phenotypes: Underestimation (CUFF-bSBP < IA-bSBP by >10 mmHg); No Mismatch (CUFF-bSBP within 10 mmHg of IA-bSBP); Overestimation (CUFF-bSBP > IA-bSBP by >10 mmHg) phenotypes. Risk of overtreatment and undertreatment, and accuracy (ARTERY society criteria: mean difference ≤5 ± 8 mmHg) were determined. A multiple linear regression model was used to assess variables associated with the bSBP difference. Underestimation (n = 142), No Mismatch (n = 136) and Overestimation (n = 25) phenotypes had relatively similar characteristics and CUFF-bSBP (124 ± 17, 122 ± 14, 127 ± 19 mmHg, P = 0.19) but different aortic SBP (133 ± 21, 120 ± 16, 112 ± 18 mmHg, P < 0.001). In the underestimation phenotype, 59% were at risk of undertreatment (14% in No Mismatch), whereas 50% in the Overestimation phenotype were at risk of overtreatment (17% in No Mismatch). CUFF-bSBP accurately estimated aortic SBP only in the No Mismatch Group (mean difference 1.6 ± 8.2 mmHg) whereas central BP never met the accuracy criteria. Male sex, higher height and active smoking were associated with lesser underestimation of bSBP difference. The brachial cuff lacks accuracy towards intraarterial BP in a significant proportion of patients, potentially leading to increased risks of BP mismanagement and inaccurate determination of central BP. This illustrates the need to improve the accuracy of cuff-based BP monitors.