Tens of thousands of people downloaded an app in their smartphones to check their blood pressure. However, the blood pressure app developed by AuraLife gave false readings to the hypertension patients, since the readings showed that their vital statistics were absolutely fine, even when they were actually at an alarming level, according to a US study.

The app called Instant Blood Pressure from AuraLife measured the blood pressure of a person when the smartphone’s top edge was placed on the left side of the chest and the right index finger was held over the camera on the phone.

However, the readings given out by the app were incorrect in four out of five cases with hypertension.

“If Instant Blood Pressure worked, it would be a revolutionary new technology that would allow for low-cost screening and management of hypertension among smartphone users,” said Dr. Timothy Plante of Johns Hopkins University in Baltimore, lead author of the study.

Dr. Plante added that erroneous readings about blood pressure are an extremely concerning factor because hypertension is considered as a silent killer since it follows an asymptomatic path, which results in severe problems, including heart disease, kidney disease and stroke.

According to the estimate provided by Plante and his colleagues in JAMA Internal Medicine, a minimum of 148,000 copies of app, which cost $4.99, were sold between June 2014 and July 2015. For investigating the app, the team used the standards that are used to test any new normal blood pressure cuff to receive US regulatory approval.

The team enrolled 85 participants, out of which, over 50% were hypertension patients and almost all of them were taking medication for the condition. Blood pressure was tested twice by app and at the same time by the regular cuffs as well. The app provided over and under estimated readings for low and high blood pressure respectively.