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24-hour blood pressure readings better predict mortality

Published: 19 April 2018

Measuring blood pressure regularly over 24 hours rather than just taking one reading at a doctor’s appointment can better predict the risk of death, according to research supported by the NIHR.

Blood pressure is usually measured at a single point during a doctor’s appointment. However, this approach can be biased by phenomena such as masked hypertension, when blood pressure is normal in the clinic but raised outside the clinic, and white-coat hypertension, where blood pressure is raised in the clinic but is normal out-of-clinic.

Ambulatory blood pressure monitoring (ABPM) involves wearing a device that measures blood pressure every 20-30 minutes over a period of 24 hours.

This new research, the largest ever cohort study of its kind, assessed 63,000 doctors’ patients who had their blood pressure tested using traditional “in clinic” methods and by a pocket-sized ABPM device.

The study, published in New England Journal of Medicine, found that measuring blood pressure using an ABPM device was a stronger predictor of all-cause and cardiovascular mortality than clinic blood-pressure measurements.

Research co-lead Professor Bryan Williams, director of the NIHR University College London Hospitals Biomedical Research Centre, said: “For decades doctors have known that blood pressure measured ‘in-clinic’ could be masked or elevated, simply because the patient was in a medical setting, and this could lead to the wrong or a missed diagnosis.

“This research is a clear game-changer, as for the first time, it definitively shows that blood pressure measured regularly during a 24-hour period predicts the risk of heart disease, stroke and death much better than blood pressure measured in a doctor’s surgery or clinic.

“Quite simply, measuring blood pressure over 24 hours is what doctors and medics should be using to make clinical decisions about treatment.”

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