Blood Pressure

AOBP vs ABPM: Which Is Better for Making a Diagnosis of Hypertension?

Automated office blood pressure (AOBP) monitoring might reduce the presence of white coat hypertension, but in-office measurements may not be as good as ambulatory blood pressure monitoring (ABPM) for getting a patient’s average blood pressure throughout the day and for making a new diagnosis of hypertension, according to new research presented at the American Heart Association’s Hypertension Sessions 2020.1

“Blood pressure varies throughout the day for all people. We focused on investigating whether having an attendant in the room matters and to determine the impact of varying amounts of rest times on blood pressure using automated readings,” said lead author Beverly Green, MD, MPH, in a press release.2 “We also evaluated the performance of AOBP monitors in making a new diagnosis of hypertension compared to 24-hour ambulatory blood pressure, which is considered the gold standard for deciding whether a patient has hypertension or not.”

To determine whether the presence of an attendant impacted the white coat effect, the researchers evaluated 130 patients aged 18 to 84 years who did not have a hypertension diagnosis or treatment at baseline and did not have hypertension, defined as blood pressure at or above 140/90 mm Hg.

Participants were included in the study if they had received ABPM testing in the prior 24-hours to baseline. They were then randomly assigned to receive attended AOBP first, unattended second (group A) or unattended AOBP first, attended second (group B). 

“AOBP was subsequently performed twice, once after 5 minutes of rest and again after 15 minutes,” the researchers wrote.

Results showed that participants undergoing automated blood pressure monitoring had significantly lower blood pressure levels than those undergoing ambulatory blood pressure monitoring, regardless of rest time or whether an attendant was present.

For making a new diagnosis of hypertension, the sensitivity of AOBP was 71.0% and the specificity was 54.1%.

“These findings indicate AOBP readings might not be the optimal way to rule in or rule out a new diagnosis of hypertension. We expected blood pressure would go down after resting more than 15 minutes, and we were surprised that it did not,” said Green.2 “When there is a question of whether blood pressure is high or normal, getting more blood pressure measurements, either by at-home testing or by getting a 24-hour ambulatory monitoring test, is likely to lead to better decision-making.”

—Amanda Balbi

References:

  1. Green B, Anderson ML, Cook AJ, et al. Automated office blood pressures for making a diagnosis of hypertension and the effect of attendance and rest time. Paper presented at: American Heart Association’s Hypertension Sessions 2020; September 10-13, 2020; Virtual.
  2. Some health care professionals use outdated guidelines to screen and diagnose hypertension. News release. American Heart Association. September 10, 2020. Accessed September 10, 2020. https://newsroom.heart.org/news/some-health-care-professionals-use-outdated-guidelines-to-screen-and-diagnose-hypertension