Accuracy Difference of Noninvasive Blood Pressure Measurements by Sex and Height

Importance: Women are at higher risk of cardiovascular events than men with similar blood pressure (BP). Whether this discrepancy in risk is associated with the accuracy of brachial cuff BP measurements is unknown. Objectives: To examine the difference in brachial cuff BP accuracy in men and women compared with invasively measured aortic BP and to evaluate whether noninvasive central BP estimation varies with sex. Design, Setting, and Participants: This cross-sectional study enrolled 500 participants without severe aortic stenosis or atrial fibrillation from January 1 to December 31, 2019, who were undergoing nonurgent coronary angiography at a tertiary care academic hospital. Exposures: Simultaneous measurements of invasive aortic BP and noninvasive BP. Main Outcomes and Measures: Sex differences in accuracy were determined by calculating the mean difference between the noninvasive measurements (brachial and noninvasive central BP) and the invasive aortic BP (reference). Linear regression and mediation analyses were performed to identify mediators between sex and brachial cuff accuracy. Results: This study included 500 participants (145 female 29% and 355 male 71%; 471 94% White; mean SD age, 66 10 years). Baseline characteristics were similar for both sexes apart from body habitus. Despite similar brachial cuff systolic BP (SBP) (mean SD, 124.5 17.7 mm Hg in women vs 124.4 16.4 in men; P = .97), invasive aortic SBP was higher in women (mean SD, 130.9 21.7 in women vs 124.7 20.1 mm Hg in men; P < .001). The brachial cuff was relatively accurate compared with invasive aortic SBP estimation in men (mean SD difference, -0.3 11.7 mm Hg) but not in women (mean SD difference, -6.5 12.1 mm Hg). Noninvasive central SBP (calibrated for mean and diastolic BP) was more accurate in women (mean SD difference, 0.6 15.3 mm Hg) than in men (mean SD difference, 8.3 14.2 mm Hg). This association of sex with accuracy was mostly mediated by height (3.4 mm Hg; 95% CI, 1.1-5.6 mm Hg; 55% mediation). Conclusions and Relevance: In this cross-sectional study, women had higher true aortic SBP than men with similar brachial cuff SBP, an association that was mostly mediated by a shorter stature. This difference in BP measurement may lead to unrecognized undertreatment of women and could partly explain why women are at greater risk for cardiovascular diseases for a given brachial cuff BP than men. These findings may justify the need to study sex-specific BP targets or integration of sex-specific parameters in BP estimation algorithms.