Usability engineering for medical devices

Medical device manufacturers are required to identify and eliminate or reduce risks related to user errors without adversely affecting the benefit-risk balance. This includes considering the device’s interfaces, ergonomics, intended users, and usage 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 summarized in a few key steps.

1. Define the use specification: The first step is to understand the circumstances of use and create a use specification.

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

3. Conduct formative evaluations and develop the device: The third step is to conduct formative evaluations and iteratively develop your device with usability in mind.

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

Usage Specifications

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

User Risk Identification

Once you have defined the device’s intended use, you can identify usage scenarios in which a usage error is likely to occur, as well as the hazards or harm they might cause. This process is best integrated with the risk management process. Usage scenarios that can be linked to a hazard are called hazard-related usage scenarios. Either all or a subset of the identified hazard-related usage 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 incorporated into the user interface specification (typically included in the medical device requirements specification or in design input documentation).

Formative evaluations

During the design and development phases, the goal is to mitigate identified usage risks through user-centered design solutions. You verify 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 that it is intuitive and that risk mitigation measures are effective. This significantly reduces the likelihood of user 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 carry out activities that qualify as formative evaluations—such as design reviews, interviews, and heuristic evaluations—as part of their normal development process. Be sure to document these activities, for example in a spreadsheet or shared workspace, as this serves as objective evidence.

Be sure to include an evaluation of labeling elements such as instructions for use, labels, and product leaflets, as these are considered part of the medical device interface. Once the device performs well in the formative evaluation, it is ready for final design and summative evaluation.

Summative Evaluation

Summative evaluation is often viewed as an obstacle prior to 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 intended to identify and correct new usability issues, but rather to validate the usability of the final design. Testing should be conducted in a realistic environment and based on realistic scenarios, involving the intended users. A test protocol should also be prepared in advance, including predefined success criteria and the required equipment.

It is important to pilot-test your planned summative evaluation, as repeating a summative evaluation with users can be both costly 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 specific requirement regarding how to document your activities, but ultimately, it might look something like this:

Usability engineering file:

• Usability Engineering Plan for a Specific Project, Device, or Group of Devices
• Usage Specifications
• 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

The extent to which the Usability Engineering File must be comprehensive 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. Contact us to learn more.