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Diagnostic and Medical Device Usability Engineering
Usability engineering is a mandatory part of EU technical documentation for both medical devices and in vitro diagnostics not an optional add-on. Under Regulation (EU) 2017/745 (MDR) and Regulation (EU) 2017/746 (IVDR), manufacturers must show that use-related risks have been identified, reduced, and validated before a device can carry the CE mark. The two regulations share the same underlying standard and process, but the GSPR clauses, risk drivers, and Notified Body expectations differ enough that they need separate GSPR checklists. This page covers both.
Medical device usability — also referred to as human factors engineering — is the application of knowledge about human behavior, capabilities, and limitations to the design of a device’s user interface, so that the device can be used safely, effectively, and as intended.
Usability is shaped by the interaction of three elements: the User, the User Interface, and the Use Environment. How these three interact during actual use determines whether the outcome is correct use or a use error and a use error can, depending on severity, lead to unsafe or ineffective use of the device.
In practice, usability is the characteristic of the user interface that makes it easier for users to perceive the information the device presents, understand it, and act on it correctly enabling them to achieve their intended goals in the intended use environment, with an acceptable level of learnability, efficiency, and user satisfaction.
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Where Usability Engineering Is Required
The obligation sits in Annex I of each regulation the General Safety and Performance Requirements (GSPRs). MDR and IVDR each maintain their own Annex I; the structure and much of the language is similar, but the specific clauses differ:
MDR 2017/745GSPR 5 & GSPR 22.2
GSPR 5: Manufacturers must reduce as far as possible the risks related to the ergonomic features of the device and the environment in which it is intended to be used (design for patient safety), and must give consideration to the technical knowledge, experience, education, training, and use environment of intended users — lay, professional, disabled, or otherwise.
GSPR 22.2 (devices for lay use): Devices intended for use by lay persons must be designed so they can be used safely and accurately at every stage of the procedure, reduce the risk of unintended injury (e.g. needle-stick), and reduce as far as possible the risk of user error.
IVDR 2017/746GSPR 5 & GSPR 19.1
GSPR 5: The IVDR equivalent of the MDR ergonomics clause — the same requirement to reduce risk from ergonomic features and account for the intended user’s knowledge, training, and use environment.
GSPR 19.1 (self-testing and near-patient testing): Devices for self-testing must be designed to perform appropriately when used by laypersons, and devices for near-patient testing must perform appropriately in the relevant use environment (e.g. patient’s home, ambulance, emergency unit). Performance data must specifically be generated in these conditions, not just in a professional lab setting.
In practice: MDR usability risk concentrates around physical interaction and lay-use handling; IVDR usability risk concentrates around correct specimen handling, result interpretation, and self-testing accuracy outside a lab environment.
The Standard IEC 62366-1 Applicable for MDR and IVDR
IEC 62366-1 (“Application of usability engineering to medical devices”) is the harmonized standard Notified Bodies expect under both MDR and IVDR. Under Article 8 of each regulation, conformity with a harmonized standard creates a presumption of conformity with the linked GSPR making IEC 62366-1 the simplest, most defensible route for either device type. A manufacturer can, in theory, demonstrate compliance without it, but that requires alternative evidence that is significantly harder to defend at audit.
- IEC 62366-1:2015 + AMD1:2020 — the core standard specifying the usability engineering process, applicable to all medical devices and IVDs alike.
- IEC/TR 62366-2:2016 — a technical report offering implementation guidance (not itself a requirement).
The standard’s scope covers software as a medical device / medical device software (MDSW) under MDR and software-driven IVDs under IVDR equally the process applies to decision-support screens, alerts, and result-interpretation workflows just as it does to physical controls.
The Usability Engineering Process
IEC 62366-1 defines one iterative, risk-based process used for both device categories:
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- Define intended users, use environments, and the user interface.
- Identify use-related hazards and hazardous situations.
- Identify and categorize critical tasks — those where a use error could cause serious harm or a wrong result.
- Develop and implement risk mitigation and design controls.
- Validate user safety and effectiveness through formative and summative evaluation.
- Document the entire process in the Usability Engineering File (UEF).
If summative validation shows unacceptable residual risk, or surfaces new use-related risks, the process loops back to redesign and re-test. For IVDR self-testing devices, this loop also connects to performance evaluation — a usability failure in result interpretation is also a performance failure.
How to build a Medical Device Technical Documentation as per MDR 2017/745? We have the answer and the right team to do it for you.
Where the Two Regulations Diverge
| Aspect | MDR 2017/745 | IVDR 2017/746 |
|---|---|---|
| Primary GSPR clauses | GSPR 5, GSPR 22.2 | GSPR 5, GSPR 19.1 |
| Core usability risk | Physical handling, ergonomics, injury risk (e.g. needle-stick) | Specimen handling, result interpretation, self-testing accuracy |
| Highest-scrutiny devices | Self-injection devices, home monitoring devices, alarm-based devices | Self-test kits (e.g. glucose, pregnancy, infectious disease), near-patient testing devices |
| Evidence tie-in | ISO 14971 risk management file | ISO 14971 risk file and performance evaluation (Annex XIII) |
| GSPR checklist | Maintained separately per MDR Annex I | Maintained separately per IVDR Annex I |
Note: if your portfolio includes both device types, maintain separate GSPR checklists for MDR and IVDR products — the clause numbering and applicable evidence differ even where the underlying usability engineering process is shared.
Formative vs. Summative Evaluation
| Aspect | Formative Evaluation | Summative Evaluation |
|---|---|---|
| Purpose | Iteratively refine the UI design during development | Confirm the final UI is safe and effective for intended users |
| Timing | Early and throughout design and development | Once design is final, before CE marking submission |
| Participants | Small samples, informal or moderated sessions | Representative user groups; sample size justified by risk and critical tasks |
| Output | Design changes, risk control updates | Objective evidence for the UEF and GSPR checklist |
IEC 62366-1 does not mandate a fixed number of summative evaluation participants for either MDR or IVDR devices — the number is justified by user groups and critical tasks. FDA human factors guidance is often used as a practical reference point (typically 15+ participants per distinct user group), and EU Notified Bodies generally expect comparable rigor for higher-risk devices under both regulations.
Building a Defensible Usability Engineering File (UEF)
Notified bodies consistently flag the same gaps in usability submissions, for MDR and IVDR alike. A well-built UEF avoids them by maintaining clear traceability across the full chain:
| Common Notified Body Finding | What a Compliant UEF Does Instead |
|---|---|
| Weak traceability from user tasks → use errors → hazards → controls → verification evidence | Maintains a single traceability matrix linking every critical task to its risk control and validation evidence |
| Usability treated as separate from risk management (ISO 14971) | Cross-references the UEF and the ISO 14971 risk file so use-related hazards feed directly into risk analysis |
| Summative evaluation run on the wrong user population | Participant selection justified against the defined intended-user profile (lay vs. professional, self-test vs. near-patient) |
| (IVDR) Performance data generated only in a professional lab, not the actual use environment | Analytical/clinical performance validated under GSPR 19.1 conditions — home, ambulance, emergency unit, as applicable |
| No justification for GSPR clauses marked "not applicable" | Every applicable/non-applicable usability-related GSPR clause documented with objective rationale, in the correct regulation's checklist |
How to build a Medical Device Technical Documentation as per MDR 2017/745? We have the answer and the right team to do it for you.
Medical Device Usability FAQ's
Is usability engineering required for both MDR and IVDR devices?
Yes. Both regulations embed usability requirements in their respective Annex I GSPRs — GSPR 5 and GSPR 22.2 under MDR, GSPR 5 and GSPR 19.1 under IVDR and both point to IEC 62366-1 as the harmonized standard for demonstrating conformity.
Can I use one Usability Engineering File for a product line that includes both device and IVD components?
The underlying usability engineering process can be shared, but the GSPR checklist and objective evidence must map back to each regulation separately for MDR and IVDR each require their own Annex I checklist, even when the usability engineering activities are run jointly.
What is Primary Operating Functions means?
A primary operating function is a function that is directly related to the safety of the medical device. Primary operating functions are identified in some product-specific medical device safety standards which require those identified primary operating functions to be an input to the usability engineering process
What is Usability Engineering?
Application of knowledge about human behaviour, abilities, limitations, and other characteristics to the design of medical devices (including software), systems, and tasks to achieve adequate usability
What is Usability Test?
Method for exploring or evaluating a user interface with intended users within a specified intended use environment
What is Use Environment?
Method for exploring or evaluating a user interface with intended users within a specified intended use environment
What is Use Error?
What is Use Scenario?
The specific sequence of tasks performed by a specific user in a specific use environment and any resulting response of the medical device. A task in a hazard-related use scenario, in which a use error can lead to significant harm, can be thought of as a ‘critical task’.
What is User, User group and User Interface?
- User: Person interacting with (i.e. operating or handling) the medical device
- User groups are subsets of users who are differentiated from other users by factors that are likely to influence their interactions with the medical device. Attributes of USER GROUPS can include age, culture, expertise
- User Interface: The means by which a user and medical device interact
Does IEC 62366-1 apply to software (MDSW and software-driven IVDs)?
Yes. Software falls within the device definition under both MDR and IVDR, so IEC 62366-1 applies with the process focused on decision-support screens, alerts, and result-interpretation workflows rather than physical controls.
What's different about usability risk for IVDR self-testing devices?
Under GSPR 19.1, self-testing IVDs must be validated for performance obtained by laypersons specifically, and near-patient testing devices must be validated in the relevant use environment (home, ambulance, emergency unit). This ties usability evaluation directly to performance evaluation evidence, not just a standalone human-factors study.
How many participants are needed for summative usability testing?
Neither MDR nor IVDR nor IEC 62366-1 sets a fixed number the sample size must be justified against user groups and critical tasks. FDA human factors guidance is commonly used as a practical benchmark (15+ per user group), and EU Notified Bodies generally expect comparable rigor for higher-risk devices under either regulation.