Clinical Impact Of 3 Versus 5-minute Delay And 30 Versus 60-second Intervals On Automated Office Blood Pressure Measurements

Background: Guidelines advise automated office blood pressure (AOBP) with an initial 5-minute delay and multiple measurements at least 60 seconds apart. Recent studies suggest that AOBP may be accurate with shorter delays or intervals, but evidence in clinical settings is limited. Objective: To evaluate shorter delays and intervals for AOBP accuracy compared to awake-time ambulatory BP measurement (ABPM). Methods: Patients referred to one hypertension (HTN) center underwent ABPM and one of four non-randomized, unattended AOBP protocols: a 3 or 5-minute delay with a 30 or 60-second interval, i.e., 3m/30s/30s, 3m/60s/60s, 5m/30s/30s and 5m/60s/60s. HTN was defined as SBP≥140 or DBP≥90 mmHg. We compared differences in mean BP and HTN classification between average AOBP and awake-time ABPM by t-tests and Fisher’s exact test. Results: Among 195 participants (mean 59±16 years, 63% women, 25% Black), overall AOBP average was 133.9±15.7/78.5±11.2. Differences between average AOBP and awake ABPM were: 1.3±14.8 mmHg (5m/60s/60s; P for difference=0.46), 7.0±16.7 mmHg (3m/60s/60s; P =0.004), 6.7±12.1 mmHg (5m/30s/30s; P <0.001), and 5.0±12.9 mmHg (3m/30s/30s; P =0.06) ( Figure ). The proportion with HTN was statistically equivalent to ABPM for the 60s arms, but significantly different for the 30s arms (both P -values for difference = 0.01). Conclusion: In this quality-improvement study, 5m/60s/60s was most similar to the awake-time ABPM average. While shorter protocols may improve AOBP adoption in clinical practice, the potential loss in accuracy should be evaluated in a larger, randomized trial.