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Study supports 'white coat effect' of doctors on blood pressure readings

Posted on March 28th 2014

A PenCLAHRC-supported systematic review led by the University of Exeter has discovered that doctors routinely record blood pressure levels that are significantly higher than those recorded by nurses. 

After examining blood pressure levels of 1,019 individuals whose readings had been taken by both doctors and nurses, the review showed that recordings taken by doctors are on average 7/4mmHg higher than when the same patients are tested by nurses or themselves. 

Lead researcher, Dr Christopher Clark said the findings, published in the British Journal of General Practice, should lead to changes in clinical practice:

"Doctors should continue to measure blood pressure as part of routine check-ups, but not where clinical decisions are being made on the outcome.  The difference we noted is enough to tip some patients over the threshold for treatment for high blood pressure, and that medication can lead to unwanted side-effects."  

The findings are thought to be the result of the patient’s physical response to being assessed by a doctor, known as the ‘white coat effect’.  Although this has been previously noted in a number of studies, Dr Clark’s research is the first comprehensive analysis of all available data to quantify the ‘white coat effect’.        

"Our results were analysed from different settings across ten countries, so we can be confident that they can be applied generalised to any healthcare environment where blood pressure is being measured. These results were all from research trials – our next task will be to examine data from GP surgeries."   

The results of this study were reported by a number of media outlets, including the BBC, Science Daily, Daily Mail, Western Morning News, and the Herald Scotland.

Dr Clarke, along with Professor John Campbell, have led on a number of hypertension projects for PenCLAHRC, including previously work on examining the organisation of hypertension care and the significance of an inter-arm blood pressure difference. You can read a summary of this research from our BITE (Brokering Innovation Through Evidence) library here.

Click here to view the ITV Westcountry news coverage for this story.

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