Usability engineering for medical devices

Medical device manufacturers are required to identify and eliminate or reduce risks related to use errors without adversely impacting the benefit–risk balance. This includes considering the device’s interfaces, ergonomics, intended users, and use environments. In this article, we provide an overview of how to structure the usability engineering process, share examples of common outputs, and answer frequently asked questions.

The usability engineering process within the EU

Usability risks are addressed through a usability engineering process. In the EU, this work is guided by the standard IEC 62366-1:2015 + AMD1:2020, which describes a usability engineering process closely linked to the risk management process defined in ISO 14971:2019. While the exact details can be found in the standard, the process can be condensed to certain key steps.

1. Define use specification: The first step is understanding the circumstances of use and creating a use specification.

2. Identify use-related risks: The second step is understanding what could go wrong and identify potential use errors, hazards, hazardous situations and risks related to usability.

3. Perform formative evaluations and develop device: The third step is conducting formative evaluations and iteratively developing your device with usability in mind.

4. Conduct summative evaluation: Lastly, the fourth step is to validate the usability of the device through summative evaluations.

Use specification

The use specification is the foundation of the whole process. Clearly defining your user, patient, environment and operating principle is crucial for identifying potential use errors, hazards and hazardous situations. Furthermore, it increases the chance of developing the right device for the right user from the start, reducing the risk of potential costly mistakes and redesigns. Take your time to consider your use specification carefully, it is worth doing right.

User Risk identification

When you have defined the device’s use specification you can identify use scenarios where a use error is likely to happen as well as what hazards or harm they might lead to. This process is advantageously integrated with the risk management process. Use scenarios that can be linked to a hazard are called hazard-related use scenarios. Either all, or a subset, of the identified hazard related use scenarios shall be reviewed, mitigated, and continuously evaluated throughout the process.

The insights and conclusions generated through these usability activities shall be translated into requirements and fed back into the user interface specification (typically included within the medical device requirements specification or in design input documentation).

Formative evaluations

During design and development, the goal is to mitigate identified use risks through user centered design solutions. You confirm that you are on the right track through continuous formative evaluations.

By regularly reviewing the device from a usability perspective and testing it with users, you can ensure it is intuitive and that risk mitigations are effective. This significantly reduces the likelihood of use errors and safety issues, while increasing the chances of a successful product launch.

Formative evaluations do not need to be complex. Low cost prototypes and simple documentation are often sufficient. Many manufacturers already perform activities that count as formative evaluations, such as design reviews, interviews, and heuristic evaluations, as part of normal development. Make sure these activities are documented, for example in a spreadsheet or shared workspace, as this serves as objective evidence.

Do not forget to include evaluation of labelling such as instructions for use, labels and product leaflets, as these are considered parts of the medical device interface. Once the device performs well in formative evaluation, it is ready for design finalization and summative evaluation.

Summative evaluation

Summative evaluation is often seen as an obstacle before product launch, but with the right planning and mindset it becomes manageable and valuable. When conducting summative evaluation, you should be confident that your device will pass the tests.

Summative evaluation is not meant for identifying and correcting new usability issues but to validate the usability of the final design. Testing should be performed in a realistic environment and be based on realistic scenarios, together with the intended users. A test protocol should also be prepared in advance, including predefined success criteria and required equipment.

Pilot testing your planned summative evaluation is important, as repeating a summative evaluation with users can be both expensive and difficult. Finally, the data is analyzed, conclusions are drawn, and the results are summarized in a report.

Documenting the usability engineering process

All the evidence shall be summarized in a usability engineering file. There is no requirement on exactly how to document your activities but in the end, it might look something like this:
Usability engineering file:

• Usability engineering plan for specific project, device or device group
• Use specification
• Use related risk analysis and Hazard-related use scenarios
• User interface evaluation plan and report or
• Formative evaluation plan and records/report
• Summative evaluation plan and records/report
• Usability engineering report

How comprehensive the Usability Engineering File must be is determined by the medical device in question.

The usability engineering process can be documented as a standalone activity or fully integrated into other development processes, such as design and development. The approach is up to your company, provided that all usability‑related elements are clearly documented and traceable.

Usability engineering goes beyond regulatory compliance. It plays a crucial role in creating safe, effective, and successful medical devices. Let’s build usability into your medical device from the start. Reach out to learn more.