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

OBJECTIVE: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.