Usability Engineering for Medical Devices: IEC 62366-1

The medical treatment of patients involves risks. These risks can be significant and may also stem from medical devices or in vitro diagnostic devices themselves. Inadequate usability of medical devices can lead to errors in use and, consequently, Harm to patients and users. For this reason, manufacturers of medical devices are required to implement a development process focused on usability engineering. This article describes the regulatory requirements for the usability of medical devices and explains the practical implementation of usability engineering in accordance with IEC 62366-1.

MDR and IVDR requirements for the usability of medical devices

The European Medical Device Regulation (EU) 2017/745 (MDR) and the In Vitro Diagnostic Medical Devices Regulation (EU) 2017/746 (IVDR) place great importance on the usability of medical devices. The MDR contains direct references in Annex I, Chapter I, Section 5 (risks due to misuse), Chapter II, Section 14.6 (ergonomics of measuring, control, and display devices), Chapter II, Section 22 (products intended for lay people), and Chapter III, Section 23 (accompanying information).

Accordingly, the manufacturer must, among other things,

reduce risks arising from the ergonomic characteristics of the product and its environment (patient safety),
consider the technical knowledge and health status of users (user safety),
design the medical device in such a way that risks of injury due to the physical properties and ergonomic characteristics of the product are reduced,
design and manufacture measuring, control, or display devices so that they comply with ergonomic principles, and
design medical devices for use by lay people accordingly and provide easily understandable information regarding their use.

In addition, there are several requirements for the instructions for use. These are found primarily in Chapter III of Annex I, which describes the requirements for the information supplied with the device.

Furthermore, the manufacturer should take the aspect of usability into account as part of the product’s verification and validation.

The consideration of usability does not end after the product is placed on the market. The manufacturer must record any incidents that occur during post-market surveillance (PMS), report them as necessary, and improve the usability of the product. The findings from market surveillance pursuant to Articles 83 through 86 of the MDR are incorporated into the risk management file and the usability engineering file. If use errors become frequent, it should be assessed whether the design, label, or instructions for use need to be adjusted.

The same applies to in vitro diagnostic medical devices (IVDs) under the IVDR. For IVDs as well, usability, risk management, performance evaluation, and market surveillance must be integrated. Annex I, Section 5 of the IVDR is not word-for-word identical to the MDR, but the requirements are very similar in substance. Section 13.7 concerns the ergonomics of display and control devices. Section 19 covers devices for self-testing and for near-patient testing and Chapter III, Section 20 addresses the information provided with the device. For self-tests and near-patient testing, usability is of particular importance because errors in use can directly affect the test result and the decisions made based on it.

Implementation of the requirements for usability of medical devices

The standard IEC 62366-1:2015 + AMD1:2020, with national implementation as DIN EN 62366-1 (VDE 0750-241-1):2021-08, describes usability engineering process. The standard is not listed as a harmonized standard in the Official Journal of the EU under the MDR/IVDR. Therefore, there is no presumption of conformity. In practice, however, the standard is considered the recognized state of the art, and its application can be used to demonstrate compliance with the relevant requirements and is expected by Notified Bodies. The process addresses the safety-related aspects of usability. The objective is to achieve an acceptable residual risk from user errors.

To this end, the standard requires the implementation of a usability engineering process that holistically addresses the intended use of the medical device and the associated activities and usage situations, such as transport, storage, installation, operation, maintenance, repair, and disposal of the medical device. The process includes measures for risk control related to the design of the user interface and for the provision of safety information.

The usability engineering process is documented in the usability engineering file. There is an accompanying technical report to the IEC 62366-1 standard that explains in more detail how a usability engineering can be structured (IEC TR 62366-2). The report is more comprehensive than the standard and addresses not only usability in terms of safety, but also, for example, accuracy, task completion, efficiency, and user satisfaction.

Since quality management according to ISO 13485 is closely linked to usability, this standard also plays an important role here. There is a direct connection to Chapter 7 (product realization) and to the subsections on design and development.

For active electrical medical devices, the supplementary standard IEC 60601-1-6 also applies, which refers to IEC 62366-1 for usability. Individual standards in the IEC 60601-2 series contain additional requirements, such as those for primary control functions.

Structure of the usability engineering process

The manufacturer plans the usability engineering process and documents the planning and results in the usability engineering file. First, the manufacturer must create a use specification. This includes, for example, the medical indication, the user group, the patient group, and the body region. It can make a difference, for instance, whether a ventilator is to be used in an ambulance or in a hospital ward.

This is followed by a systematic analysis of the user interface about safety-critical characteristics that could lead to “use errors.” Subsequently, the manufacturer identifies hazards and hazardous situations as part of the medical device’s risk analysis. At this stage, the standard specifies that findings from comparable medical devices should be considered.

The manufacturer then identifies and describes hazard-related usage scenarios, including the relevant tasks, usage steps, and potential use errors. From these hazard-related usage scenarios, the manufacturer selects those that are relevant for the summative evaluation (Section 5.5 of the standard). The selection must be justified. This is followed by the creation of a user interface specification, which also includes verifiable technical requirements as well as information on whether accompanying documentation and specific training are required. The derivation of the safety-related characteristics of the user interface should be transparently linked to the results of risk management.

The manufacturer must then evaluate the user interface. The standard requires a user interface evaluation plan that documents the objectives and methods of all formative and summative evaluations (Section 5.7). The manufacturer then designs and implements the user interface, accompanying this step with formative evaluations (Section 5.8 of the standard). The process concludes with a summative evaluation, through which the manufacturer demonstrates that the hazard-related usage scenarios are safely managed (Section 5.9).

For existing user interfaces, the standard provides for the concept of the user Interface of unknown provenance (UOUP). In such cases, the manufacturer does not have to go through the entire process from scratch but may apply the alternative, appropriately scaled process specified in Annex C if sufficient development records in accordance with IEC 62366-1 are not available. This is particularly relevant for existing products.

Benefits of usability engineering

A usable medical device offers advantages even beyond regulatory requirements. For example, the manufacturer receives valuable information early on that can shorten time-to-market. The risk of design flaws in the user interface - which can be time-consuming and expensive to perform a correction on - is reduced.

In addition, systematically conducted usability engineering should have a positive impact on the quality of the technical documentation and its review.

Another benefit is greater user acceptance due to improved ease of use. This can lead to competitive advantages. User training is also easier when the manufacturer focuses on intuitive operating concepts.

Overall, less consultancy and support from the manufacturer should be required to teach users operating concepts and workflows. Furthermore, users can operate the Product more safely and efficiently.

Usability engineering for medical software

Even with medical software, user errors can have significant implications for patient safety. Causes include misleading screen displays, unclear operating procedures, error-prone data entry, or user overload due to an excess of information. Therefore, manufacturers should consider the user interface as a safety-critical component of the product early in the development process.

The requirements of IEC 62366-1 can also be applied to software products. The starting point is the definition of the intended user groups, the application environment, and the intended use. Based on this, potential use errors are analyzed and linked to risk management in accordance with ISO 14971. The resulting requirements for the user interface are reviewed during design and development through formative evaluations and ultimately validated as part of a summative evaluation.

For medical software, the design of user interfaces, navigation through workflows, the presentation of medical information, alarm and warning concepts, and the prevention of input errors are particularly important.

Conclusion

Manufacturers should not neglect a product’s usability. This applies equally to medical devices under the MDR and in vitro diagnostic medical devices under the IVDR, insofar as usability is relevant to safety. The usability engineering process is integrated with risk management according to ISO 14971. Hazards arising from use errors are incorporated into the risk analysis, and risk control measures influence the design of the user interface.

A consistently implemented usability engineering process leads to higher user satisfaction. Use errors occur less frequently, and users’ interaction with the product becomes more efficient and safer.

To align product features with user needs, Usability should be considered early in the design and development process. We are happy to assist you in the implementation of usability engineering in accordance with standards and integrating it into your design and development processes as well as your approval processes.