Best Selling Smartphone Blood Pressure App Gave Wrong Results

A best-selling smartphone app that purported to measure blood pressure actually delivered highly inaccurate results, according to a research letter in JAMA Internal Medicine.  The finding could cause genuine medical harm for the large number of people who use the app. In addition, the study adds new fuel to the fiery debate about the reliability of mobile health apps and how this rapidly growing field should be regulated.

The Instant Blood Pressure (IBP) app, which was a best selling health app on both the Apple and Android app stores, employed an unconventional method to estimate blood pressure, pulse transit time. Using a private, unvalidated algorithm, the app calculated a blood pressure measurement when the user put the top edge of the phone on the left side of the chest and the right index finger over the camera.

Timothy Plante and colleagues at Johns Hopkins compared the accuracy of the app to that of a standard sphygmomanometer in 85 people.  The results showed that the IBP app was “highly inaccurate” with potentially serious health consequences. In general, they found, the app underestimated higher blood pressure levels and overestimated lower blood pressure levels. The results suggest that more than three-quarters of people with hypertension would be “falsely reassured” that their blood pressure was normal.

Although the IBP app is no longer available on the App stores, the authors note that “it is installed on a vast number of iPhones; furthermore, several ‘me-too’ apps are still available.”

More Questions About Mobile Health

In an interview Plante said that he is a big supporter in general of mobile health but that he was concerned that this app and many similar ones “fall through the cracks.”

Plante said “the system isn’t set up to handle these apps. It’s not like drugs. Any app developer can come up with a clever idea and release it. There’s no mechanism for oversight.”

Plante noted that the $4.99 app was “wildly successful.” This is “good because it means that people want to use it, but it’s bad because unfortunately the developers made something that is unsafe and is inaccurate and could potentially put people at harm.” Plante also said he is concerned because doctors now don’t know enough about the multitude of mobile apps their patients are using and have no way to evaluate them.

David Albert is a cardiologist who invented the AliveCor, a smartphone-based mobile ECG system that has received FDA approval and high praise from cardiologists and other experts. In an interview Albert said he is concerned about the large number of dangerous apps.

The precise reasons for the removal of the IBP app from the app stores is unknown. “The app stores are not well policed,” Albert said. “The fact that there may be others out there is a scary proposition, but I would hope that the app stores and the FDA will do a better job.”

Albert said that blood pressure devices are a class 2 device that fall under FDA regulation. “This is an app that turns your phone into a medical device, and as a class 2 device it is then covered by the FDA,” he said.

“The medical community has ignored this issue,” said Albert. “I’m glad these authors took the time to show this up.” Albert is concerned about the reputation of the mobile health industry. “This hurts us, I don’t want to be associated with them.”

I asked the FDA for a comment on the JAMA Int Med paper and the larger problem with mobile devices. Here is the statement they sent me:

“Generally the FDA does not comment on specific studies, but evaluates them as part of the body of evidence to further our understanding about a particular issue and assist in our mission to protect public health. The FDA is reviewing the findings of the paper.

“In general, the agency believes consumers and health care providers should expect the same level of assurance of safety and efficacy in devices designed to work on a mobile platform as they do from other types of medical devices. Regarding FDA-regulated mobile medical apps, the agency has outlined its intent to apply the same risk-based approach it uses to assure safety and effectiveness for other medical devices. As with existing medical devices, manufacturers of these innovative medical devices are also expected and should take into account risks introduced due to the technology. The FDA is committed to policies like this, which seek to balance patient safety while encouraging innovation.”

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