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Independents' Day

One in seven blood pressure monitors inaccurate

By Lilian Anekwe

Researchers are advising GPs to test their practice blood pressure devices after a primary care study found as many as 14% are inaccurate.

A study of blood pressure monitors used in practices in Oxfordshire found one device in every seven did not attain accuracy standards.

Researchers from the University of Oxford tested 604 mercury, aneroid and digital monitors used in 38 practices in Oxfordshire, and measured the accuracy of the devices at 50, 100, 150, 200 and 250 mm Hg.

At each of 50, 100 and 150 mm Hg aneroid devices were the least accurate and mercury sphygmanometers were the most accurate, but there were no significant differences observed at both 200 and 250 mm Hg.

Overall, 14% of all devices – mercury, aneroid and digital – were more than 3 mm Hg away from the true value. 2.5% of readings from mercury devices were inaccurate by more than 3 mm Hg, compared with 10% of readings from digital devices and 16% of readings from aneroid machines.

Dr Christine A'Court, a GP in Carterton, Oxfordshire and a researcher in the University of Oxford's Department of Primary Health Care, concluded: ‘In this cross-sectional study we were unable to prove that testing improved the accuracy of manometers in use.'

‘One in seven devices did not attain accuracy standards. This could lead to anxiety, unnecessary visits, over-diagnosis and over treatment of hypertension, or in some patients, the opposite.'

And she advised GPs: ‘Aneroid manometers are the least reliable, particularly non-branded devices likely to have been free gifts from pharmaceutical representatives. If you have held on to your mercury device, carry on doing so. But you may eventually have to dispose of it.'

‘If you purchase a digital device buy a well-known validated brand as listed on the British Hypertension Society website.'

The research was presented at the South West Society for Academic Primary Care conference in Oxford this week.

Researchers are advising GPs to test their practice blood pressure devices Researchers are advising GPs to test their practice blood pressure devices

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