Hypertension may be misdiagnosed

Dr Martin Turner, Research Fellow from Sydney University, recently used data from a UK survey of over 1400 sphygmomanometers (blood pressure monitors) to estimate how often hypertension diagnosis may be incorrectly made in Australia.

"If Australian sphygmomanometers have error patterns similar to those in the UK, then about 70,000 Australians may have undetected high blood pressure because of sphygmomanometer errors," said Dr Turner.

"And about 84,000 adults may be incorrectly diagnosed as having high blood pressure," he added.

In Australia, medical measuring instruments such as sphygmomanometers are approved for sale by the Therapeutic Goods Administration. But there is no requirement for them to be checked once they are sold.

The problem is not limited to blood pressure measurements. Optometrists and ophthalmologists use tonometers to measure pressure in the eyes to screen for and monitor glaucoma. Spirometers are used to diagnose lung function problems, especially the damage caused by cigarette smoking.

All these devices need regular calibration against a reliable standard, but once sold, there is no requirement on users that they are ever checked. Contrast this with supermarket scales which have to be approved for trade use and are then checked while they are used for that purpose.

In his paper at the Metrology Society of Australia conference to be held in Geelong on 19 – 21 October, 2011, Dr Turner calls for medical measuring devices to be calibrated regularly against national reference standards.

"We need a calibration system for medical measuring devices that is at least on par with the system used for supermarket scales."

The Metrology Society of Australia is an organisation for measurement experts working in fields as diverse as the pharmaceutical and fuel industries.