A recent study in the Journal of the American Society of Hypertension1 discussed seven android apps where users pressed their fingers on iphone screens or used cameras to measure blood pressure. Examination of these apps has shown the readings obtained to be wildly inaccurate and potentially dangerous. However, the apps themselves have been downloaded between 900,000 and 2.4 million times and are, presumably, widely used.

The danger in using apps as medical devices is that many application developers do not understand the need for clinical studies to establish efficacy. The current guidance from FDA divides the types of apps available on a smart phone into two distinct categories. First, mobile apps are “software programs that run on smartphones and other mobile communication devices. They can also be accessories that attach to a smartphone or other mobile communication devices, or a combination of accessories and software”. Second, mobile medical apps are “medical devices that are mobile apps, meet the definition of a medical device and are an accessory to a regulated medical device or transform a mobile platform into a regulated medical device”.

Mobile medical apps are to be treated using the same regulatory framework that applies to traditional medical devices. Using a camera or screen to measure blood pressure is subject to CFR 21, 870.1120 as a class two medical device, yet at the time of writing, FDA has not issued a warning letter to any of the companies in question. In a strange twist of events the FTC stepped in based on reports of false advertising from concerned medical professionals.

The blood pressure apps represent obvious cases of non-compliance with federal regulation, and it’s easy to understand the clinical concern that has been expressed. Hypertension is a population health issue and large scale reduction of medication compliance by patients who believe their condition has resolved would represent a major social cost. It’s bad enough that hypertension is the “silent killer” – no further muting is required.

What then of simpler cases? Consider, for example, a weight tracking application that incorrectly reports deltas between measurements? FDA has chosen to not regulate these applications because the potential for harm is significantly lower. Presumably, the patient should be able to detect the incorrect arithmetic and apply appropriate corrections. It’s also unlikely that this data will be used in isolation. A quick visual inspection of your body should indicate if a change has occurred!

The reason the distinction between medical apps and medical device apps is important is that the cost of developing a medical device can be very high. A traditional medical device filing expense increases with the class of the device. Loosely speaking class can be equated to the risk to the patient posed by the device. Some examples; elastic bandages, and hand-held surgical instruments are class one, infusion pumps, acupuncture needles, and surgical drapes are class two, HIV tests, pacemakers, and pulse generators are class three. Development costs typically tend to increase with class.

So, how much does it really cost to develop a medical device app? Probably more than you’d expect. A simple class one device may require basic paperwork and filing fees and range in the thousands of dollars plus manufacturing costs. Class two devices that are linked to an existing medical device garner a lot of support from the existing approval for that device and do not represent a major incremental cost. Class two standalone medical devices apps can be very expensive. Consider for example, the blood pressure app mentioned earlier. Since the technique has never been validated, a clinical trial will probably be required, and this cost can run into the millions.

The FDA is understandably skittish about damping current innovation in the medical app space. There is a fine balance to be struck between fostering and destroying what has the potential to be one of the greatest democratizing movements in healthcare. It would not be politic in the current environment to write warning letters to nascent app companies, and indeed, it’s too early to understand how to regulate this new world.


  1. http://www.ashjournal.com/article/S1933-1711(14)00899-7/abstract

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