New ankle blood pressure method could prevent 750 misdiagnoses a year

A new way to interpret blood pressure readings taken from the ankle could help people unable to use traditional arm cuffs, including stroke survivors and those with limb differences.

The method, developed using statistical modelling, estimates arm blood pressure from ankle measurements more accurately than existing approaches.

It aims to address a significant care gap affecting tens of thousands globally.

Professor Chris Clark, who led the study, said: “Our new method will give a more accurate blood pressure reading for around two per cent more people.

“This doesn’t sound a big number but remember, around a third of adults have high blood pressure and once you get into your 60s it’s more than half of the adults.

“The NHS Health Check Programme diagnoses 38,000 new cases annually in England alone, so two per cent equates to 750 fewer potential misdiagnoses per year in England, and tens of thousands globally.”

Researchers from the University of Exeter Medical School analysed data from 33,710 people (average age 58, 45 per cent female) to build a personalised model showing how ankle readings relate to arm values.

They also used the data to predict health outcomes, including the risk of heart attacks.

An online calculator has been created to help healthcare professionals and patients interpret ankle blood pressure readings more reliably.

High blood pressure, a major contributor to heart disease, stroke and kidney problems, affects more than one billion people worldwide.

While it is typically measured on the arm, this is not always possible due to disability, upper limb loss, or arm dysfunction following a stroke.

Ankle blood pressure readings are generally higher than arm values, but medical guidelines rely only on arm measurements, increasing the risk of misdiagnosis.

The research found that the new method could improve the accuracy of blood pressure readings for around two per cent of patients.

This work may help tackle a long-standing health inequality by improving diagnostic accuracy for those unable to use arm cuffs.

It is estimated that 10,000 adults in the UK live with upper limb loss, while 75 per cent of the country’s 1.3 million stroke survivors have upper limb dysfunction, making accurate arm-based blood pressure monitoring difficult or impossible.

The study was supported by the Stroke Association and the Thalidomide Trust.

Juliet Bouverie OBE, chief executive of the Stroke Association, said: “Someone in the UK has a stroke every five minutes, with high blood pressure accounting for around half of those.

“Around two-thirds of stroke survivors will leave hospital with some form of disability, including paralysis in an arm, which can prevent getting accurate blood pressure readings from the affected limb.

“Many stroke survivors feel anxious about having another stroke, so receiving an accurate blood pressure reading in the ankle will not only provide benefits in the primary prevention of stroke, but importantly in easing the minds of stroke survivors who are already dealing with the devastating impact of stroke.”