Healthcare Technology Featured Article

June 29, 2020

SaMD vs SiMD: What's the Difference?

The healthcare industry has always relied on new technology to drive it forward and improve the care that patients get. From the invention of things like the magnifying glass and the stethoscope centuries ago to complex machines like CT scanners and MRI invented just a few decades ago, technology is what allows medicine to evolve, adapt, and advance.

Today is no exception. Technology is growing at a rapid pace and doctors, researchers, scientists, and computer programmers are all working together to create new technology that revolutionizes healthcare. This technology allows the professionals who use them to save lives and to help people maintain better overall health. In 2020, some of the biggest technological developments in the medical world come in the form of software.

Medical industry software comes in several forms and to understand what this amazing software is doing for medicine, we must understand the difference between software types. The two largest categories of medical software that is revolutionizing the industry is software as a medical device (SaMD) and Software in a medical device (SiMD). Here we will discuss the differences between the two types of software and cite examples of each type to help give you a better understanding of both categories.

Software as a medical device

The best way to think about and remember the differences between these two types of software is right in the name of each. Software IN a medical device is just that, software that is part of another medical device that helps it function in some way. Software AS a medical device means that the software itself is the device.

To qualify as SaMD, software needs to function completely independently of existing medical devices. Any software that is run or helps run things like an MRI, EKG, EHR, X-ray, insulin pump or any number of other devices qualify as SiMD, not as SaMD. SaMD is run with non-medical devices such as smartphones, tablets, smartwatches, laptops, or other computing platforms. I

While SaMD does not deal with the running of a medical device, they often work in conjunction with these devices. SaMD can analyze the pictures from an MRI or X-ray to look for issues, monitor EKG and alert doctors when something goes wrong, and create a treatment plan that is executed by an insulin pump to help patients manage their diabetes. Because SaMD and medical devices so often work together is a big reason that SaMD and SiMD are often confused.

According to Orthogonal, there are 2 additional major defining characteristics of SaMD. They list these features as “Improved health outcomes powered by data”, and “Faster production and feedback to drive faster innovation”. The software is able to process data and come to conclusions from it much faster than humans which is why it is improving patient outcomes. The reason it drives faster innovation is that it is portable, cheaper, and easier to update than traditional medical devices, and, since it is almost always connected to the internet, creators can get real-time feedback on what is working and what is not to make adjustments as needed.

A great, tangible example of SaMD is a product like Omron’s HeartGuide. This is a blood pressure monitor that works with a smartwatch. Healthcare Weekly has a great review of the product but the general idea is that it is a smartwatch with many of the features you will find in most smartwatches on the market today. What sets this apart though as SaMD is that it runs medical software that turns the watch into an accurate blood pressure monitor.

Products like these are so exciting because of what they mean to the population and the medical industry. There are millions of people around the world who suffer from high blood pressure and hypertension. Having wearable tech that allows people to monitor their own blood pressure regularly and reporting back to their healthcare providers when needed allows more personal ownership over health and healthcare, saves valuable time for doctors, and will ultimately lead to a society that is healthier overall.

Software in a medical device

The SiMD category is often confused with SaMD but much of it is self-explanatory. If the software in question helps in any way to run a medical device, it is SiMD. Software that powers the mechanics of a medical device or processes the information that is produced by a medical device is obviously considered SiMD. Also, software that controls the device remotely is SiMD.

Outside of doing these things though, there are many other software programs that are considered SiMD that have some of the characteristics of SaMD which is where things can get confusing. For example, SaMD almost always involves some level of internet or wireless connectivity. However, if software helps create that connectivity through WiFi or Bluetooth, it is considered SiMD.

In some scenarios, a mobile app – which is almost always associated with SaMD – can actually be SiMD. The FDA has a more exhaustive explanation of what types of mobile apps are not medical devices but the general idea is as follows. For some medical devices, the primary way to read or see the results that the device creates may be a mobile app powered by medical software. The key here is the word “primary”. The fact that you cannot use the medical device without this software, makes it SiMD. If there is another way to read the results and the app just allows you to have the results in a portable fashion or analyze those results in some way, then the app software is SaMD.


Now that you know more about SaMD and SiMD you should have a better idea about the differences between the two. Even now though, some of this still may seem incredibly confusing and convoluted. In these cases, the best way to make the distinction between the two is by asking two simple questions. These are, is this software a medical device unto itself? Or, is this software part of another medical device? Answer these and you always know SaMD vs SiMD.

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