A novel approach to office blood pressure measurement: 30-minute office blood pressure vs daytime ambulatory blood pressure

Abstract

Purpose: Current office blood pressure measurement (OBPM) is often not executed according to guidelines and cannot prevent the white-coat effect. Serial, automated, oscillometric OBPM has the potential to overcome both these problems. We therefore developed a 30-minute OBPM method that we compared with daytime ambulatory blood pressure.

Methods: Patients referred to a primary care diagnostic center for 24-hour ambulatory blood pressure monitoring (ABPM) had their blood pressure measured using the same validated ABPM device for both ABPM and 30-minute OBPMs. During 30-minute OBPM, blood pressure was measured automatically every 5 minutes with the patient sitting alone in a quiet room. The mean 30-minute OBPM (based on t = 5 to t = 30 minutes) was compared with mean daytime ABPM using paired t tests and the approach described by Bland and Altman on method comparison.

Results: We analyzed data from 84 patients (mean age 57 years; 61% female). Systolic and diastolic blood pressures differed from 0 to 2 mm Hg (95% confidence interval, -2 to 2 mm Hg and from 0 to 3 mm Hg) between mean 30-minute OBPM and daytime ABPM, respectively. The limits of agreement were between -19 and 19 mm Hg for systolic and -10 and 13 mm Hg for diastolic blood pressures. Both 30-minute OBPM and daytime ABPM classified normotension, white-coat hypertension, masked hypertension, and sustained hypertension equally.

Conclusions: The 30-minute OBPM appears to agree well with daytime ABPM and has the potential to detect white-coat and masked hypertension. This finding makes 30-minute OBPM a promising new method to determine blood pressure during diagnosis and follow-up of patients with elevated blood pressures.

Trial registration: ClinicalTrials.gov NCT00457483.

Figures

Figure 1.

Course of mean systolic blood pressure during 30 minutes of measurement. Note: Error bars represent 95% confidence intervals of the standard error of the mean.

Figure 2a.

Bland-Altman plot of difference in mean arterial pressure between 30-minute OBPM and daytime ABPM against mean mean arterial pressure. ABPM = 24-hour ambulatory blood pressure monitoring; MAP = mean arterial pressure; OBPM = office blood pressure measurement.

Figure 2b.

Bland-Altman plot of difference in systolic blood pressure between 30-minute OBPM and daytime ABPM against mean systolic blood pressure. ABPM = 24-hour ambulatory blood pressure monitoring; OBPM = office blood pressure measurement.

Figure 2c.

Bland-Altman plot of difference in diastolic blood pressure between 30-minute OBPM and daytime ABPM against mean diastolic blood pressure. ABPM = 24-hour ambulatory blood pressure monitoring; OBPM = office blood pressure measurement.