A best-selling blood pressure app gives false readings almost 80 per cent of the time, according to a new study

A best-selling blood pressure app gives false readings almost 80 per cent of the time, according to a new study

The app, called Instant Blood Pressure, purports to accurately measure blood pressure by placing a smartphone on a person’s chest with a finger over the built-in camera lens

However, the app is potentially putting users’ health at risk by missing high blood pressure in nearly eight out of ten people, according to scientists from John Hopkins University

The app was first released in June 2014 - and spent 156 days in the top 50 best-selling charts, with at least 950 purchases a day

Study co-author Dr Timothy Plante, of Johns Hopkins, said: ’Because this app does such a terrible job measuring blood pressure, it could lead to irreparable harm by masking the true risk of heart attacks and strokes in people who rely on the accuracy of this information.’

More than half of the participants had self-reported hypertension - and 91 per cent reported taking anti-hypertensive medications

Study co-author Dr Seth Martin said that the scientists were ’skeptical that even very talented people could design an app that could accurately measure blood pressure’

He added: ’Because of the absence of any rigorous scientific testing, there was no evidence that it worked or didn’t work.’

Each of the study participants had his or her resting blood pressure measured twice through a reliable automated blood pressure monitor commonly used in research studies to avoid measure variation or error

They also used the app to measure their own blood pressure twice on the same day.The study found that blood pressures measurements from the app were ’overwhelmingly inaccurate’

Close to 80 per cent of those with clinically high blood pressure showed as having normal blood pressure with the app

The scientists noted that it’s unclear how the app arrives at a blood pressure number.They suggest, in the study published in the journal JAMA Internal Medicine, that the app doesn’t attempt to measure true blood pressure

Instead, it gives a population-derived estimate based on the user’s age, height, weight, sex and heart rate, they said

The app cost roughly $4.99 (?3.50) to download - but was withdrawn in July 2015 for unexplained reasons