Usability Engineering: More Than Just Compliance – A True Success Factor
Usability in Medical Technology – Lessons from the Past, Demands for the Future
What do the Ford Pinto and the Therac-25 have in common? Both led to preventable fatalities in the 1970s and 1980s, ultimately prompting the development of new safety standards—initially in the automotive sector, and later in medical technology.
Severe design flaws in the Ford Pinto’s fuel tank placement contributed to the introduction of Failure Modes and Effects Analysis (FMEA) as a formal risk assessment method. Meanwhile, the Therac-25—a computer-controlled radiation therapy device—became emblematic of the critical role of usability, with deadly consequences caused by software faults and poorly designed user interfaces.
A more recent example involves infusion pumps. Between 2005 and 2009, the majority of incidents reported to the U.S. Food and Drug Administration (FDA) related to infusion pumps were linked to “inadequate user interface design (human factors issues).” In response, the FDA launched the “Infusion Pump Improvement Initiative” in 2010, which led to the 2011 draft guidance “Applying Human Factors and Usability Engineering to Medical Devices.”
This growing history of incidents—many due to user errors—has dramatically increased regulatory attention. As a result, usability now plays an increasingly central role in international standards, regulatory guidelines, and oversight frameworks. The most widely adopted standard in this area is IEC 62366.
- Usability Engineering: More Than Just Compliance — A True Success Factor
- From Ergonomics to IEC 62366: How Usability Became a Requirement
- Regulatory Challenges or Clear Guidelines? What Manufacturers Need to Know
- Proper Usability Documentation: What the Usability Engineering File Must Contain
- UX in Medical Devices: Where Regulation Ends and Innovations Begins Value Starts
- Between Effort and Innovation: Key Challenges for Manufacturers
- Conclusion: Usability — From Nice-to-Have to Essential
Usability Engineering: More Than Just Compliance — A True Success Factor
Technological innovation in medical devices – such as smart glucose monitors or AI-assisted diagnostics – is increasingly focusing not only on safety, but also on intuitive usability as a key to market success. Particularly in digital and patient-centric applications, ease of use often determines whether a product is accepted and used correctly in hospitals or home settings.
As technical complexity increases and more non-professionals use medical devices, usability demands are rising. Usability is no longer a “nice-to-have” feature – it has become a core component of product development, compliance, and patient safety.
A structured usability engineering process provides manufacturers and users with major advantages:
- Improved Safety: User-centered design reduces the risk of use errors.
- Efficiency and Cost Reduction: "Usability by design" minimizes costly redesigns and cuts down on training and support needs after market launch.
- Greater Acceptance: Intuitive products are favored by both healthcare professionals and patients.
- Regulatory Compliance: Usability engineering helps meet international regulatory and normative standards.
When usability is addressed early in development, manufacturers benefit from lower costs, quicker approvals, and more user-friendly products. Good usability isn’t just a cost factor – it’s a competitive advantage.
From Ergonomics to IEC 62366: How Usability Became a Requirement
Usability isn’t new in medical technology. Human-machine interaction was considered well before IEC 62366 – originally influenced by IT and software development. Early regulatory roots trace back to ISO 9241 in the 1990s, which laid foundational principles for ergonomic and user-friendly systems.
Initially focused on office monitors and basic interfaces, it soon became clear that poor usability in high-risk areas – like aviation or healthcare – could have serious consequences. Standards like IEC 60601 and IEC 62366 later brought these insights into medical technology.
The FDA led the way with its first Human Factors Engineering (HFE) guidance in 2000. In 2006, IEC 60601-1-6 introduced usability requirements for medical electrical equipment.
A key milestone came in 2007 with IEC 62366, which defined a usability engineering process specifically for medical devices. The 2015 revision divided the standard into two parts: Part 1 (IEC 62366-1:2015, updated in 2020) – legally binding and focused on risk-based usability – and Part 2 (IEC/TR 62366-2:2016) – a technical guideline for practical application. Today, IEC 62366-1 is the international benchmark for medical device usability and is recognized by the FDA, although full harmonization with EU MDR 2017/745 is still pending.
1997FDA Guidance
FDA references Human Factors in Design Control Guidance (21 CFR 820.30).1997Software Norm
Ergonomic principles for display workstations.1998Software Norm
Defines usability as effectiveness, efficiency, and satisfaction (updated in 2018).2000FDA Guidance
First FDA guidance on HFE.2006Medical Device/Software Norm
IEC 60601-1-6 introduces usability requirements.
2007Medical Device Norm
IEC 62366 defines usability engineering for medical devices.2011Software Norm
ISO/IEC 25010 introduces usability as a software quality characteristic.2015Medical Device Norm
IEC 62366-1 emphasizes risk integration.2016Medizinprodukte Leitfaden
IEC/TR 62366-2 offers practical implementation support.2016Medizinprodukte Norm
ISO 13485 includes usability in development inputs.2017Medizinprodukte Regulierung
EU MDR mandates usability in Annex I.2023FDA Guidance
FDA publishes Human Factors Q&A for combination products.2024KI Regulierung
EU AI Act begins regulating AI in medical technology.2025Medizinprodukte Norm
Upcoming ISO standards will address AI and machine learning in medtech.???Final draft
ISO/FDIS 18374 Dentistry — Artificial intelligence (AI) and augmented intelligence (AuI) based 2D radiograph analysis — Data generation, data annotation and data processing draft
This development highlights how usability has become a globally recognized aspect of safety and quality. Regulatory frameworks will continue evolving, particularly as AI transforms healthcare.
Regulatory Challenges or Clear Guidelines? What Manufacturers Need to Know
Regulatory usability requirements aim to ensure medical devices can be used safely and effectively by both professionals and laypersons – minimizing the risk of use errors.
Usability must be addressed systematically throughout the entire product lifecycle and thoroughly documented.
Under EU MDR, usability is required under the General Safety and Performance Requirements (Annex I). This includes devices used by non-professionals, especially in homecare settings. Post-market surveillance (Art. 83) specifically calls for continuous collection and evaluation of usability data. Relevant documentation must be included in the Technical Documentation (Annex II).
In the U.S., the FDA treats Human Factors as part of Design Controls – particularly during validation. Both the FDA and MDR expect usability and risk management activities to be closely linked.
Key regulatory usability expectations:
- Systematic application of a usability engineering process that analyzes and addresses user requirements and risks due to misuse (IEC 62366-1, FDA guidances).
- Consideration of usability already during product design and evidence of this, particularly as part of design validation (MDR 2017/745 Annex I, FDA 21 CFR 820.30, FDA Human Factors Guidance, ISO 13485).
- Continuous monitoring throughout the entire product lifecycle (MDR 2017/745 Article 83).
- Coordination with risk management in identifying and minimizing risks from use errors (ISO 14971).
- Creation of a Usability Engineering File to document results (IEC 62366-1, FDA Human Factors Guidance) as part of the approval-relevant documentation (MDR 2017/745 Annex II).
Usability vs. related disciplines:
Although usability shares touchpoints with risk management and development, it focuses specifically on the interaction between user and product. Understanding these interfaces is key to compliance. UX, on the other hand, expands on usability by including emotional and motivational factors (see Chapter 5).
Proper Usability Documentation: What the Usability Engineering File Must Contain
Even the best usability is meaningless without proof. That’s where the Usability Engineering File (UEF) – or, in the U.S., the Human Factors Engineering (HFE) Report – becomes crucial. IEC 62366-1 references the UEF 13 times as a core element in demonstrating compliance.
Usability Engineering File (UEF):
The UEF documents all usability-related activities during development. It may be a standalone file or part of broader documentation. It is mandatory for all medical devices and serves as formal evidence of regulatory conformity.
Key components of the UEF:
- Use Specification: Description of the intended medical indication, patient group, body parts or tissue types, users, usage environment, and functional principle. (Interface to design dossier: Intended Use and User Needs)
- Use-related Hazards and Hazardous Situations: Identification of hazards and analysis of potential hazardous situations for patients, users, and others. (Interface to risk management file)
- Hazard-related Use Scenarios and Selection Scheme: Descriptions must include all tasks, their sequence, and the severity of resulting harm. (Interface to risk management file). Severity is often used as a criterion for inclusion in summative evaluation.
- User Interface Specification: Testable technical requirements for the user interface and its safety-relevant functions, plus requirements for accompanying documentation and training. (Interface to design dossier: Design Input)
- User Interface Design und Evaluation: During development, formative evaluations are conducted to optimize the UI design, whose suitability is then assessed in summative evaluation. The UI design, planning, execution, and results of evaluations are documented in the UEF. (Interface to design dossier: Design Output, Design Verification, Design Validation)
Since IEC 62366-1 focuses on safety, the UEF often overlaps with the risk management file and benefits from shared documentation.
Human Factors Engineering (HFE) Report
The FDA guidance “Applying Human Factors and Usability Engineering to Medical Devices” (2016) calls for comparable documentation, with a stronger emphasis on actual usability testing – especially of critical tasks.
Outline of the Human Factors Engineering (HFE) Report (according to Table A-1)
- Conclusion
Product overview, functionality, target user group, and justification for Human Factors Engineering. - Use Specifications
Description of users, capabilities, scenarios, environments, and training. - Description of device user interface
Visuals, labeling, and anticipated interactions. - Summary of known use problems
(Use-related Hazards and Hazardous Situations of the UEF) Known use problems from previous or similar products. - Analysis of hazards and risks associated with use of the device
Identification of possible use errors, risk assessment, and mitigation strategies. - Summary of preliminary analyses and evaluations (Formative Evaluation of the UEF)
Results from conducted evaluations and resulting design modifications. - Description and categorization of critical tasks (Identification of Hazard-related Use Scenarios and Selection Scheme of the UEF)
Identification of safety-critical interactions and required testing. - Details of human factors validation testing (Summative Evaluation of the UEF)
Test procedures, data collection, and evaluation.
Smart design is essential – but only solid documentation makes a product truly market-ready.
UX in Medical Devices: Where Regulation Ends and Innovation Begins
User Experience (UX) originated in software and product design, and was shaped significantly by Don Norman – Apple’s first "User Experience Architect" in the 1990s. While related to Human Factors and Usability, UX goes a step further by focusing on emotional and aesthetic aspects.
Although UX is not explicitly mentioned in most regulations, it is indirectly addressed in IEC 62366-1, MDR, and FDA HFE Guidance – all aiming to ensure safe, comfortable, and user-friendly design. More detailed definitions appear in ISO/IEC 25010, ISO/IEC 25066, and ISO 9241-210:
- ISO 9241-210 provides development principles for UX and defines it as: "a person’s perceptions and responses resulting from the use or anticipated use of a product, system, or service."
- ISO/IEC 25010 offers measurable software quality attributes to support regulatory compliance.
- ISO/IEC 25066 describes methods to assess usability and UX in software systems.
Benefits of UX Beyond Usability
UX considers the entire user experience and offers advantages beyond basic usability:
- Emotional Acceptance: UX builds trust and satisfaction, especially for lay users.
- Stress Reduction: A positive design reduces uncertainty and boosts user confidence.
- First Impressions Count: Good UX enhances acceptance and brand loyalty.
- Sustained Use: Devices with strong UX are used more frequently and longer.
- Competitive Edge: Appealing, comfortable designs set products apart.
UX inspires confidence, increases engagement, and elevates medical devices into user experiences – beyond basic usability.
Between Effort and Innovation: Key Challenges for Manufacturers
Meeting usability regulations is still demanding and resource-intensive. Integrating usability early and aligning it with internal processes is essential. Five key challenge areas stand out:
1. Costs & Ressources: Usability as a Long-Term Investment
- Authentic usability tests with real users in real environments require time and budget.
- Budget limits often reduce usability engineering to basic compliance – losing its strategic value.
2. Interfaces with Internal Processes
- Risk Management & Usability: IEC 62366-1 and ISO 14971 demand tight linkage. Use errors are risks that must be documented.
- Software Development & Usability: Agile methods (like Scrum) require continuous usability checks, increasing documentation needs.
3. Different Global Regulations
- Different markets have varying usability demands:
- EU (MDR): Clear usability demands but no strict testing requirements.
- USA (FDA): Strong focus on human factors validation testing for critical tasks.
- China and others: Often lack specific guidance – MDR/FDA compliance advised.
- Global harmonization remains a key goal.
4. Technological Innovations: Digital Challenges
- AI-Based Devices: Must be transparent and trustworthy for users.
- Apps & Telehealth: Usability proof required for non-professional users.
- Connected Devices: Central control interfaces must be intuitive.
- Automation & Robotics: Complex interactions require careful usability risk assessment.
- 3D Printing & Customization: Require usability proof for personalized solutions.
5. Various User Groups - Different Needs
- Devices must meet needs of:
- Professionals: High workload, advanced skills, fast workflows.
- Patients & Laypersons: Limited knowledge, independent use at home.
- Elderly & Disabled: Need accessible, robust design.
- One-size-fits-all approaches won’t work – different use cases must be tested and considered.
Conclusion: Usability — From Nice-to-Have to Essential
Usability has grown from a specialized niche into a regulatory essential. The challenge for manufacturers is to integrate usability early without losing sight of cost, deadlines, or compliance.
Emerging technologies, growing homecare markets, and global regulatory convergence are redefining usability in medtech. Future-ready companies embed usability engineering into risk management, (software) development, and post-market activities.
Tomorrow’s medical products must be intuitive, safe, and user-friendly. Equip your team with practical workshops and expert support to master usability – for safe, effective, and successful devices.
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