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The ultimate guide to Software as a Medical Device (SaMD, SiMD, SxMD) classification

The classification of medical devices and in vitro diagnostic (IVD) devices is an important regulatory aspect that varies between the United States (US) and the European Union (EU). Each regulatory body has its own system for classifying these devices based on the intended use and the risk associated with the use of the device, and the classification determines the level of regulatory control and requirements for approval.

Software based devices (Software in Medical Device, SiMD and Software as Medical Device, SaMD, together, SxMD) follow the same rules as other medical devices and IVDs in terms of classification. Here's a guide comparing the medical device and IVD classification systems in the US and EU:

United States (US)

In the US, the classification of software medical devices follows the same framework as other medical devices, considering risk and intended use. 

  1. Class I: Low-risk software that supports or provides general health and wellness information (e.g., fitness apps).

  2. Class II: Moderate-risk software that may be used to diagnose or treat medical conditions (e.g., clinical decision support software).

  3. Class III: High-risk software that is integral to the functioning of a high-risk medical device (e.g., software in a Class III implantable device).

European Union (EU)

In the EU, the classification of software medical devices aligns with the risk-based approach outlined in the Medical Device Regulation (MDR) and In Vitro Diagnostic Regulation (IVDR). The risk classes for software are similar to those for other medical devices.

  1. Class I: Low-risk software with a well-established safety profile.

  2. Class IIa and IIb: Moderate to high-risk software, where the intended use and complexity influence the classification.

  3. Class III: High-risk software that is critical for the device's safety and performance.

When it comes to SxMD (Software as/in a Medical Device) and in vitro diagnostic (IVD) devices, the International Electrotechnical Commission (IEC) 62304 standard becomes a crucial reference for software lifecycle processes. IEC 62304 provides a framework for the development and maintenance of medical device software, including software in medical devices and standalone software that is a medical device.

Additionally, it's important to consider IEC 62304 in the discussion and link it to the regulatory classifications in both the United States (US) and the European Union (EU) to understand it's context.

Software Medical Device Classification

IEC 62304

IEC 62304 classifies software into three safety classes based on the potential harm that may result from a software failure:

  1. Class A: No injury or damage to health is possible.

  2. Class B: Non-serious injury is possible.

  3. Class C: Death or serious injury is possible.

The classification is based on the software's contribution to the overall device and the impact of a failure.

Linking IEC 62304 to Regulatory Classifications

  1. IEC 62304 and Class A Software:

    • Class A software, which poses no risk of injury, aligns with low-risk classifications in both the US and EU. This may include software providing general health information.

  2. IEC 62304 and Class B Software:

    • Class B software, associated with non-serious injury in case of failure, may correspond to moderate-risk classifications in the US and EU. Clinical decision support software could fall into this category.

  3. IEC 62304 and Class C Software:

    • Class C software, associated with the potential for death or serious injury, aligns with high-risk classifications in both regions. Software integral to Class III medical devices, for instance, may fall into this category.

Understanding the classification of software medical devices according to IEC 62304 and linking it to the regulatory classifications in the US and EU is vital for manufacturers developing these technologies. By following the principles outlined in IEC 62304 and considering the risk and intended use, manufacturers can navigate the regulatory landscape, ensuring the safety and effectiveness of software medical devices and IVDs across global markets.

About the Author
Ann Vankrunkelsven
RA/QA Manager