Evaluation of blood pressure measurement and agreement in an academic health sciences center

Abstract

The authors assessed the process of blood pressure (BP) measurement and level of adherence to recommended procedures at representative sites throughout a large academic health sciences center. A casual observer assessed the setting and observed the process, noting the equipment, technique, and BP recorded by site personnel. A trained observer then repeated the patient's BP measurement following American Heart Association recommendations. Significant biases were observed between measurements by site personnel and the trained observer. Site personnel reported on average an increased systolic BP (SBP) of 5.66 mm Hg (95% confidence interval [CI], 3.09-8.23; P<.001) and a decreased diastolic BP (DBP) of -2.96 mm Hg (95% CI, -5.05 to -0.87; P=.005). Overall, 41% of patients had a ≥10-mm Hg difference in SBP between measurements. Similarly, 54% had differences of ≥5 mm Hg in DBP between measurements. Inaccurate BP measurement and poor technique may lead to misclassification, misdiagnosis, and inappropriate medical decisions. Concordance of measured SBP between our site personnel and trained observer was less than optimal. Several areas for improvement were identified. Routine calibration and use of system-wide standardized equipment, establishment of BP measurement protocols, and periodic technique and equipment recertification can be addressed in future quality initiatives.

Figure 1

Graphical representation of observed blood pressure (BP) differences using Bland‐Altman method plotting differences in BP of site personnel and trained observer against the average BP. For systolic BP (SBP), there was agreement within ±10 mm Hg in 70 observations (59%) between site personnel and the trained observer. For diastolic BP (DBP), there was agreement in 72 (46%) of observations that fell within ±5 mm Hg.

Figure 2

Diagram highlighting conclusions of bias for individual protocol violations. Arm not being bare, conversation, and cuff not at heart level demonstrated the greatest mean differences of >5 mm Hg. Feet not flat and legs crossed did not appear to influence systolic blood pressure (SBP) differences (diff) as much as other variables.