New HealthPartners Institute study shows that measuring blood pressure manually results in low readings compared to automated measurements

The results, published in JAMA Network Open, have implications for managing hypertension and the quality measures used to assess health system performance

Bloomington, Minn. – A new HealthPartners Institute study published in JAMA Network Open showed the diagnosis of hypertension was more than 4 percentage points higher (23.4% vs 19.1%) when blood pressure was measured with an automated monitor compared to when blood pressure was measured with the traditional method using a stethoscope.

The discrepancy, researchers believe, is caused by clinicians’ tendency to record lower readings when using manual measures, resulting in readings that can influence hypertension diagnosis and treatments.

“Over the decades, we’ve known of flaws with traditional blood pressure monitoring but our data now quantifies how it compares to automated monitors,” said Thomas Kottke, MD, senior investigator with HealthPartners Institute and lead author on the study. “By capturing these data, we can work toward higher quality measurement across all of health care.”

In 2012, HealthPartners stopped using manual blood pressure monitors and started using automated ones. Researchers have now analyzed exactly how these two tools and techniques affect blood pressure readings.

They compared 849,978 blood pressure measurements taken with manual monitors to 691,249 blood pressure measurements taken with automated ones. After the automated monitors were implemented, fewer blood pressure readings were below values like 140/90 or 130/80 mmHg. Hypertension rates also increased significantly following the implementation of automated monitors.

While automated monitors are now standard at HealthPartners, they are not used consistently across all health systems. This inconsistency may be underrepresenting the rates of hypertension across the country. In addition, quality metrics used to grade the performance of health care systems may appear more favorable for those that still use the traditional manual monitors.

“There are a lot of possible reasons why clinicians record lower blood pressures with manual measurement. Maybe they want their patients to be more satisfied with care, or maybe they’re rushed during the clinic visit,” said Kottke. “In any case, we know that automated machines reduce variation and give more reliable blood pressure readings.”