Blood Pressure Readings Differ by Method and Location
New evidence highlights how office, home, and ambulatory blood pressure readings vary and why multiple methods may be needed for accurate diagnosis.
A large systematic review and network meta-analysis found that blood pressure measurements can differ significantly depending on where and how they are taken, with the biggest discrepancies seen at higher blood pressure levels. The findings underscore the need for clinicians to use multiple measurement methods, particularly out-of-office monitoring, to improve hypertension diagnosis and management.
Study Details
Published in Annals of Internal Medicine, the analysis reviewed 65 studies involving over 40,000 adults up to October 2024. The research compared office-based blood pressure measurements (OBPM), home readings, and ambulatory monitoring over 24 hours. Investigators sought to clarify how these readings diverge and whether differences depend on blood pressure levels.
Methodology
Studies included patients with blood pressure recorded by at least two methods:
Standardized office-based readings taken by professionals following research protocols
Automated office readings (unattended)
Convenient office readings (without strict protocols)
At-home self-measurements
Ambulatory monitoring with repeated measurements over 24 hours, including daytime and nighttime
The reference standard was research-grade office readings. Researchers compared mean differences and assessed how disparities changed across blood pressure ranges.
Key Findings
Nocturnal ambulatory readings were on average 18 mm Hg lower than office reference values.
24-hour ambulatory readings averaged 8.6 mm Hg lower (95% CI, 6.9-10.2).
Home readings were 4.6 mm Hg lower (95% CI, 2.8-6.3).
Daytime ambulatory and automated office readings were roughly 4 mm Hg lower than the office reference.
Differences grew with higher blood pressure levels as much as 31 mm Hg lower at systolic readings in the 180s, compared with almost no difference in the 120s.
Implications for Practice
For patients:
Blood pressure measured at home or with a 24-hour device may be lower than in the doctor’s office.
White-coat and masked hypertension can mislead both patients and clinicians if office readings are the only method used.
Consistency in using the same method for tracking progress is important.
For clinicians:
Multiple measurement techniques should be used before diagnosing or adjusting treatment for hypertension.
Out-of-office monitoring (home or ambulatory) should be prioritized, especially for patients with elevated or fluctuating readings.
Guidelines may need refinement to incorporate BP-level-specific thresholds rather than fixed conversions.
The study supports European Society of Cardiology recommendations that systolic blood pressure treatment targets (120–129 mm Hg) be applied consistently across office, home, and daytime ambulatory settings.