Introduction
In medical device regulation, safety is often associated with materials, electrical performance, or clinical evidence. However, regulatory experience shows that a significant number of adverse events do not occur because a device fails technically—but because it is used incorrectly.
This is where IEC 62366, the international standard for Usability Engineering and Human Factors, becomes critical.
Under EU MDR 2017/745, usability is no longer treated as a design preference or user training issue. It is a regulatory requirement directly linked to patient safety, risk management, and clinical performance. Notified Bodies increasingly scrutinise usability documentation, especially for devices used in high-pressure environments or by lay users.
This blog provides a practical, regulatory-focused explanation of IEC 62366, how it fits into the MDR framework, and how manufacturers can avoid common compliance pitfalls.
What Is IEC 62366?
IEC 62366 is an international standard that specifies a process for analysing, specifying, developing, and evaluating the usability of medical devices.
The objective of the standard is to:
- Reduce use-related risks
- Prevent use errors and foreseeable misuse
- Ensure devices can be used safely and effectively by intended users
Importantly, IEC 62366 does not aim to make devices “easy to use” for convenience alone. Its core purpose is risk control—specifically, controlling risks that arise from the interaction between the user and the device.
Why Usability Is a Regulatory Requirement Under EU MDR
EU MDR places strong emphasis on:
- Risk reduction “as far as possible”
- Safety in real-world conditions
- Protection against misuse
Usability directly supports these principles.
Under MDR:
- Use-related risks must be identified in the Risk Management File (ISO 14971)
- Risk controls must prioritise inherent safety by design
- Information for safety (warnings, IFU) is a last resort, not a primary control
IEC 62366 provides the structured framework to meet these expectations.
Notified Bodies now routinely ask:
- How were use-related hazards identified?
- Were foreseeable misuse scenarios considered?
- Was usability validation conducted with representative users?
Understanding Use Error vs User Error
A critical concept in IEC 62366 is the distinction between use error and user error.
A use error occurs when:
- A device is used incorrectly
- Due to poor design, unclear interface, or confusing labeling
- Even when the user is appropriately trained
IEC 62366 makes it clear:
Use error is not the user’s fault—it is a design responsibility.
This shift in thinking is essential. Regulators expect manufacturers to anticipate human behaviour, not assume perfect use.
When Does IEC 62366 Apply?
IEC 62366 applies to:
- All medical devices
- All risk classes (Class I to Class III)
- Hardware, software, and combination devices
- Devices used by healthcare professionals and lay users
If a human interacts with the device in any way—operation, setup, cleaning, interpretation of results—usability engineering applies.
This is especially critical for:
- Home-use devices
- Emergency-use devices
- Disposable or frequently handled products
- Devices with user interfaces or instructions
Core Elements of IEC 62366
IEC 62366 follows a structured usability engineering process. Key elements include:
1. Use Specification
Defines:
- Intended users (HCP, patient, caregiver)
- Use environments (hospital, home, emergency)
- User profiles (training, experience, limitations)
2. Identification of Primary Operating Functions
Identifies tasks essential for:
- Correct device operation
- Safety and clinical performance
Errors in these tasks could result in harm.
3. Use-Related Risk Analysis
Evaluates:
- Potential use errors
- Foreseeable misuse
- Resulting hazardous situations
This analysis must link directly with the ISO 14971 Risk Management File.
4. Risk Control Through Design
IEC 62366 prioritises:
- Inherent safety by design
- Protective measures
- Information for safety
Relying solely on training or warnings is not sufficient.
5. Formative Evaluation
Formative evaluations are iterative usability assessments conducted during development.
They help:
- Identify design weaknesses early
- Refine interfaces and instructions
- Reduce risks before final validation
These are exploratory but still documented.
6. Usability Validation
Usability validation is a formal confirmation that:
- Intended users can use the device safely
- In realistic use scenarios
- Without unacceptable risk
This is not optional and is often reviewed closely by Notified Bodies.
The Usability Engineering File (UEF)
Compliance with IEC 62366 is demonstrated through a Usability Engineering File (UEF).
A typical UEF includes:
- Use specification
- Task analysis
- Use-related risk analysis
- Formative evaluation summaries
- Usability validation plan and report
- Conclusions on residual use-related risks
The UEF must be:
- Consistent with the Risk Management File
- Aligned with labeling and IFU
- Referenced in the technical documentation
Linkage with ISO 14971, CER, and IFU
One of the most common regulatory findings is poor integration.
Regulators expect:
- Use-related hazards → captured in RMF
- Usability validation outcomes → reflected in CER
- Risk control measures → visible in design and IFU
For example:
- If a device has a complex setup step, this risk must appear in:
- Risk analysis
- Usability validation
- Instructions for use
Any mismatch raises red flags.
Common IEC 62366 Compliance Mistakes
Manufacturers frequently face delays due to:
- Treating usability as training only
- No documented usability validation
- Ignoring foreseeable misuse
- Missing linkage with ISO 14971
- Inconsistent IFU and device design
- Assuming low-risk devices don’t need usability analysis
Under MDR, these gaps are rarely overlooked.
Why IEC 62366 Is Especially Important for Startups
For startups, usability engineering is often delayed until late development stages.
This is risky.
Late usability findings can lead to:
- Design changes
- Re-testing
- Labeling revisions
- Submission delays
Early integration of IEC 62366:
- Reduces rework
- Strengthens regulatory submissions
- Improves overall device safety
Conclusion: Usability Is Safety
IEC 62366 is not about aesthetics or convenience.
It is about protecting patients and users from foreseeable harm.
Under EU MDR, regulators expect manufacturers to:
- Anticipate how devices are actually used
- Identify where users may struggle or err
- Design solutions that prevent harm before it occurs
When implemented correctly, usability engineering:
- Reduces regulatory risk
- Improves product quality
- Strengthens patient safety
In today’s regulatory landscape, usability is not optional—it is fundamental.
