Are Automated Office Blood Pressure Readings More Variable Than Home Readings?

Abstract

A recent report from the American Heart Association stated that automated office blood pressure (AOBP) is preferred for evaluating office blood pressure (BP) because it is more accurate and devoid of white coat effect, which is mostly caused by higher systolic BP readings. However, AOBP has been criticized for being too variable to be used for identifying patients with possible hypertension. We, therefore, compared AOBP with home BP monitoring (HBPM) with respect to variability as determined by their relationship with the gold standard for determining BP status, awake ambulatory BP (ABP). The main focus was on systolic BP. Data on AOBP, HBPM, and awake ABP were collected on 300 patients referred from the community for 24-hour ambulatory BP monitoring. The SD of the difference between mean systolic awake ABP (136.4±11.5) and AOBP (131.2±15.7) was 13.6 mm Hg compared with 13.1 for the SD of the difference ( P =0.52) between the systolic awake ABP and the HBPM (136.7±16.1). Coefficients of correlation were slightly lower for systolic awake ABP versus AOBP ( r =0.54) compared with HBPM ( r =0.60). Coefficients of variation for AOBP (12.0%) and HBPM (11.8%) and variances between AOBP and HBPM were similar. Of the 139 patients with hypertension as defined by a manual office systolic BP ≥140 mm Hg, variability in BP readings as determined by the SDs of the mean difference versus awake ABP were similar ( P =0.56) for AOBP (14.6) and HBPM (13.9). Overall, both systolic AOBP and HBPM exhibited a similar degree of variability as assessed by the various methods.