The usability engineering process (UE process) is the systematic, risk-based development process for the analysis, specification, design, verification and validation of the safe use of a medical device. In the context of IEC 62366-1, the focus is on identifying and controlling use-related risks. The process combines user research, use-related risk analysis, iterative design and evaluation into a traceably documented approach within product development.
- Objective and position in the product development process
- Analysis phase: understanding the context of use and the users
- Use-related risk analysis as the central steering activity
- User interface specification and design development
- Formative evaluation as an iterative optimization process
- Summative evaluation and demonstration of safe use
- Regulatory reference
- Frequently asked questions (FAQ)
Objective and position in the product development process
The UE process pursues the goal of detecting use errors with potential safety effects early and of preventing them through suitable design or limiting their effects. Unlike general user experience or usability optimization, the regulatory UE process concentrates primarily on safety-relevant aspects of use. The process typically begins already in early development phases and accompanies the entire product lifecycle; results feed into design decisions, risk management activities and regulatory evidence.
Analysis phase: understanding the context of use and the users
At the beginning, the intended use, user groups, use environments and the relevant use scenarios are determined systematically. The results are often documented in the use specification. Typical methods are context analysis, contextual inquiry, field observations, interviews, task analysis, hierarchical task analysis (HTA) and workflow analysis. A frequent mistake is to consider only the intended use and to overlook rare but safety-critical use situations.
Use-related risk analysis as the central steering activity
The use-related risk analysis forms the link between usability engineering and risk management conforming to ISO 14971. Potential use situations in which use errors can lead to hazards or harm are identified. At the center are the identification of characteristics of the user interface related to safety, potential use errors, hazards, hazardous situations and hazard-related use scenarios. In addition to possible new problems, known usability problems of comparable products are also included. The analysis is continued iteratively and updated with every relevant design change. In practice, it is often underestimated how strongly changes to the user interface can affect risks that have already been assessed.
User interface specification and design development
The results are documented in the user interface specification, which serves as the central link between use requirements, identified use risks, design solutions and evaluation activities. Based on the analysis results, requirements for the user interface are derived and documented, among other things on information presentation, controls, alarm concepts, labeling, instructions for use and training requirements. The design should always be risk-based: Measures such as protection against operating errors, unambiguous feedback, forcing functions or improved visibility of critical information serve to reduce risk. A typical mistake is to derive UI requirements exclusively from technical requirements, without sufficient reference to use risks and user needs.
Formative evaluation as an iterative optimization process
Formative evaluations serve to detect weaknesses of the design early. They are not a one-off activity but accompany several development cycles. Typical methods are usability tests with prototypes, expert reviews, cognitive walkthroughs, heuristic evaluations and simulations of use situations. In the regulatory context, the documentation of the identified problems, their causes and the resulting design changes is often more important than the mere number of usability problems found.
Summative evaluation and demonstration of safe use
The summative evaluation (human factors validation testing) provides objective evidence that the user interface can be used safely. In contrast to formative tests, no design changes may be made any more during a summative evaluation; the focus is on demonstrating the effectiveness of risk controls already implemented. Of particular importance are realistic use scenarios, representative user groups, critical tasks and the analysis of use errors and close calls that occurred. The summative evaluation regularly forms an essential component of regulatory submissions and of the usability engineering file.
Regulatory reference
IEC 62366-1 describes a formal process for the analysis, specification, development and evaluation of the usability of medical devices with respect to safety, from the use specification through the identification of known or foreseeable hazards and hazardous situations to the definition of UI-related requirements, evaluation and documentation in the usability engineering file. IEC 62366-2 supplements this with application guidance and practical recommendations for implementing the process beyond the normative requirements. Use-related risks must be taken into account within risk management according to ISO 14971; the usability engineering activities provide essential input data for this. In its human factors guidance, the FDA recommends applying a structured human factors or usability engineering process to reduce use-related risks and, for many products with potentially serious consequences of use errors, expects human factors validation data as part of regulatory submissions. The process does not end with the summative evaluation: Results from post-market surveillance, complaints, vigilance reports and field observations can provide indications of new use-related risks and make an update of the use-related risk analysis and of the usability engineering file necessary.
The usability engineering process connects analysis, design, formative iteration and summative evidence into a continuous, risk-based approach according to IEC 62366-1. It does not end with the market launch but accompanies the product across the entire lifecycle.
Frequently asked questions (FAQ)
Is the usability engineering process identical to human factors engineering?
In the regulatory medical device context, both terms are used largely synonymously. The FDA prefers the term human factors engineering, while IEC 62366 speaks primarily of usability engineering.
Can a summative evaluation replace missing formative activities?
No. The summative evaluation serves to demonstrate the control of identified risks. It does not replace iterative optimization during development.
Do instructions for use and training belong to the usability engineering process?
Yes. The instructions for use are part of the user interface, and training and training materials act directly on use. Both must therefore be taken into account in analysis, risk assessment and evaluation.
Is the UE process relevant only for software products?
No. IEC 62366-1 applies to medical devices in general. Mechanical, electromechanical, active and software-based products can equally have use-related risks.
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More about our usability engineeringSources
- IEC 62366-1:2015+AMD1:2020, Medical devices, Part 1: Application of usability engineering to medical devices
- IEC/TR 62366-2:2016, Medical devices, Part 2: Guidance on the application of usability engineering to medical devices
- ISO 14971:2019, Medical devices, Application of risk management to medical devices