SOP Usability Engineering

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1. Purpose

The purpose of this SOP is to establish a systematic process for usability engineering in the design and development of medical devices, ensuring compliance with IEC 62366-1 and FDA usability guidance requirements. This includes a focus on user needs, usability assessment, and risk management.

2. Scope

This SOP applies to all usability engineering activities related to the design and development of medical devices. It encompasses user research, usability requirements, design evaluation, and documentation, with a focus on formative and summative testing.

3. Process

The phases defined here are aligned with the phases in SOP Design Control. Summative usability testing is recommended but not required for medical products that generally pose low risk to users or have minimal potential for usability risk and use errors when used.

3.1 Planning & Input Phase

Objective: To understand user characteristics, needs, contexts of use, and requirements.

Steps:

1. Identify User Groups:
   • Define primary, secondary, and tertiary users of the device, considering demographics, experience levels, and environments.
2. Conduct User Research:
   • Use methods such as interviews, surveys, informal discussions, and contextual inquiries to gather data on user needs, goals, and pain points.
   • Detail findings as the Voice of Customer that informs user needs.
3. Define Use Scenarios:
   • Develop use scenarios that describe how users will interact with the device in real-world settings.
4. Create User Objective and User Profile:
   • Summarize user characteristics and their goals regarding the device's use
5. Define Usability Requirements:
   • Create specific, measurable usability requirements, such as ease of use, learnability, and error rates.
   • Example: "Users should be able to complete the primary task within 5 minutes with no more than 2 errors."

3.2 Design and Development Phase

Objective: To create design solutions that meet usability requirements.

Steps:

1. Compile Usability Engineering Information File (UEIF) or Usability of Unknown Provenance (UOUP), as needed:
   • Include all usability-related documents, such as user needs, requirements, test plans, and results.
2. Develop Prototypes:
   • Create low-fidelity (e.g., sketches, wireframes) and high-fidelity prototypes (e.g., interactive digital mockups) of the device.
3. Conduct Iterative Formative Testing:
   • Test prototypes with potential users to identify usability issues.
   • Use methods such as usability testing sessions and heuristic evaluations.
   • Document findings and recommendations as needed and use for design improvements.
4. Perform Perception, Cognition, and Action Analysis:
   • Analyze how users perceive information, process it, and take action based on their interactions with the device.
   • Integrate findings into design iterations.
5. Conduct Single Point Failure Mode Assessment:
   • Perform a failure mode and effects analysis (uFMEA) or fault tree analysis (FTA) to identify potential usability-related failure points that could impact safety or effectiveness, if needed.

3.3 Verification and Validation Phase

Objective: To confirm that the device meets established usability requirements.

Steps:

1. Conduct Formative Testing:
   • Carry out formative usability testing throughout the design process to identify and address usability issues early.
   • Document findings and make necessary design adjustments.
2. Plan and Execute Summative Testing:
   • Conduct summative usability tests with representative users using the final design.
   • Use test that mimic actual usage conditions when possible.
   • Collect data on task performance, user errors, user feedback, and satisfaction ratings, as needed.
3. Analyze Test Results:
   • Prepare a Usability Evaluation Report detailing findings, recommendations, and compliance with usability requirements.
4. Review and Approve Usability Findings:
   • Present findings to stakeholders, review and approve usability results.

3.4 Market Release and Post-Market Phase: Usability Monitoring

Objective: To monitor usability issues and user feedback after market release.

Steps:

1. Establish a Monitoring Plan:
   • Develop a plan for collecting post-market user feedback, such as surveys or interviews. This is described in SOP Post-Market Surveillance.
2. Analyze Feedback:
   • Regularly review user feedback to identify any emerging usability issues.
3. Implement Changes as Necessary:
   • Develop and implement corrective actions for any identified usability problems, as required.
   • Document changes in the Usability Engineering Information File (UEIF).

4. Documentation

• User Needs
• System and subsystem requirements (including usability requirements)
• Usability Evaluation Plan, Protocol, and Report
• Usability Engineering Information File (UEIF) / Usability of Unknown Provenance (UOUP)
• Perception, Cognition, Action Analysis Reports, as needed
• uFMEA or FTA Documentation, as needed

5. Training

All personnel involved in usability engineering must receive training on this SOP and relevant usability principles and methods.

6. References

• IEC 62366-1: Medical Devices—Application of Usability Engineering to Medical Devices
• FDA Guidance on Usability Engineering
• MDR 2017/745 Annex I, Section 5
• IVDR 2017/746 Annex I, Section 5
• SOP Design Control
• SOP Software Development