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Usability of Unknown Provenance (UOUP)

Medical devices have been required to integrate usability engineering principles and user interface design characteristics into their safety design and development process within the last 20 years since medical device risk management introduced the concept of user error in the 2000 version of IEC 14971 (annex A). In 2004, the first edition of 60601-1-6 was published for introducing usability engineering processes specifically for electrical medical equipment. A second edition was published only two years later in 2006 to implement a number of corrections to the design process.

The following year, in 2007, 62366 was introduced for the usability engineering design processes of both passive as well as active medical devices. By 2008, the standard was harmonized and adopted as the recognized definitive means for establishing a usability engineering process for medical devices in Europe.

In 2009, ANSI/AAMI published HE75 for Human Factors engineering as the American counterpart of usability design principles. This standard featured a more prescriptive approach to the concept of human factors engineering different from usability. Not until the next revision of 62366 would the concepts be re-aligned in a more consistent approach.

The term ‘usability engineering’, considered synonymous with ‘human factors engineering’ which focuses on evaluating the quality of user interfaces that result in rapid learning, user satisfaction, and efficient interactions. The term ‘usability’ is a quality that refers to the ability of a human to interact easily and relatively error-free with a system or product. Concepts such as ‘user-friendly’ and ‘intuitive’ have been used to describe facets of usability which relate to subjective attributes regarding whether a system or device works and acts in the way the user expects, therefore avoiding frustration and annoyance in executing the device intention.

Neither the 62366 standard, nor any of its predecessors ever provided guidance for how the process should be implemented and documented for legacy medical device user interfaces that were designed prior to the publication of the standards. It was expected that for medical devices to maintain a state of the art status compliant with ER2 of the MDD, the manufacturers would have to implement a usability design procedure retrospectively on these legacy devices.

Until 2015, when a second revision of 62366 was published together with a “part 2” technical report intended to provide more clarity on how to integrate usability engineering principles and practices to the development processes. In this version of the standard, an additional (normative) annex C was created for evaluating user interface of unknown provenance (UOUP).  Suddenly, there is guidance available for manufacturers with legacy devices, or component user interfaces, that were already on the market prior to the publication of these standards. The annex C approach allows manufacturers to use post-market data for unmodified aspects of the design to assess whether use errors are present.

The Annex C approach significantly streamlines the usability process requiring only, with the exception of a use specification in accordance with section 5.1 of the standard, that a thorough risk analysis has been reviewed and documented for use error as below:

  1. Review of Post-Production information – The available post-production information, including complaints and field reports, should be reviewed with a focus on use error-related incidents or near incidents. A review of the information should also identify any new hazards or hazardous situations that could have been preventable by a usability analysis.
  2. Risk control – A full risk analysis should be documented with a focus on use errors, ensuring that all hazards and hazardous situations have been identified and residual risks are reduced as low as possible. When changes to a user interface are necessary to further mitigate unacceptable residual risk, then those modifications are not relevant to UOUP and are susceptible to the full usability design process.
  3. Residual Risk Evaluation - With a basis on any new information identified in the previous steps, the overall residual risk must be re-evaluated and the result documented in the usability engineering file or the risk management file.

When completed, the documentation will comprise the usability engineering file and potentially referencing the risk management documentation ensuring that residual risk is acceptable for risks of a usability or use error-related origin.

Only unmodified user interfaces that were designed prior to the publication of the standard (2007), or parts of the user interface that are of unknown provenance for which design records do not exist are relevant to the Annex C approach. In the event that a user interface is re-designed or modified, including the addition of a new software feature, the changed parts of the user interface become subject to the full usability process requirements clause 5 of the standard. The unmodified parts of the user interface may continue to be evaluated using the annex C approach outlined above.

While the newest version of usability standards allows exceptions for legacy devices, the publication of the Medical Devices Regulation 2017/745 sees a slightly increased dependency on usability to highlight the safety and performance of medical devices in Europe without exception for legacy devices of unknown provenance. Post-market surveillance requirements expect feedback data gathered by the manufacturer to identify “options to improve the usability, performance and safety of the device” (MDR article 83). The requirements for the UDI system consider, “usability enhancements that are not for safety purposes” (Annex VI). And usability is referenced in the MDCG guidance documents which provide interpretation of the MDR requirements related to implant cards requiring the manufacturer to “investigate, by means of an ergonomic analysis or ergonomic usability test procedure” (MDCG 2019-8) that the provided instructions are sufficient.

In consideration of this increased dependency on usability engineering procedures, there is further impetus to implement a usability engineering process into the design of legacy devices. The EU MDR does not permit manufacturers to “grandfather” legacy devices formerly complying with the MDD to access the EU. And the MDR continues to propagate the requirement to substantiate a state-of-the-art safety and performance for all medical devices. The manufacturers of medical devices will need to rationalize how maintenance of a legacy device substantiates this requirement.

In summary, the concept of usability engineering of medical devices has seen a remarkable development within the last 20 years, fostering new generations of medical devices that have been designed with the user’s comfort and ease of use in mind. Only recently, the challenge of implementing a usability design process retrospectively on legacy devices has been addressed by the myriad standards that have been published regarding usability, giving manufacturers an alternative option for demonstrating conformity with the regulations through a streamlined approach focused on risk management of the usability features of the user interface. User interfaces of unknown provenance may continue to be placed in the market without a retrospective re-creation of design documents and the summative testing required to validate the user requirements.

Should you have questions on the applied usability design procedures of legacy medical devices or applicability of UOUP to your medical device, we encourage you to contact a Qserve consultant to discuss your options and provide a detailed analysis of the requirements to maintain your device in the market.

 

Post date: June 04, 2020
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