The Instant Blood Pressure (IBP) app claims to accurately monitor blood pressure with only a smartphone and no other hardware, but a new study found that this isn’t really the case. Researchers found that the app misses high blood pressure in 8 out of 10 cases, giving patients a false sense of security.

Timothy B. Plante, M.D., of the Johns Hopkins University School of Medicine, Baltimore, and coauthors looked at the accuracy and precision of IBP. The app works simply by placing a cellphone on the chest with a finger. It seemed to be quite an intriguing new way of measuring blood pressure, and not one that was rigorously tested, at least not in a scientific way. Plante and Seth Martin, M.D., M.H.S., an assistant professor in the Division of Cardiology at the Johns Hopkins University School of Medicine wanted to see just how accurate IBP is.

“We were skeptical that even very talented people could design an app that could accurately measure blood pressure in such a different way,” Martin says. “Because of the absence of any rigorous scientific testing, there was no evidence that it worked or didn’t work.”

The results were overwhelmingly inaccurate. Close to 80 percent of those with clinically high blood pressure showed normal blood pressure on the app. That’s much worse than even just random guesses, and it could be a big problem. IBP has been downloaded by over 100,000 people which could be misled to believe that they blood pressure is normal, when in fact it isn’t.

“Because this app does such a terrible job measuring blood pressure,” says Plante, “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.”

Smartphone apps are become more and more popular, but they are in no way a reliable replacement for proper medical information. The technology could provide valuable, personalized information, but it has to use a scientific approach.

“We think there is definitely a role for smartphone technology in health care, but because of the significant risk of harm to users who get inaccurate information, the results of our study speak to the need for scientific validation and regulation of these apps before they reach consumers,” says Timothy B. Plante, M.D., a fellow in the Division of General Internal Medicine at the Johns Hopkins University School of Medicine.

The app has been discontinued in 2015 for unclear reasons, but since it has been so heavily downloaded, many people could still be at risk.

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