By Jeff Morang | Director of Human Factors Engineering • BlackHӓgen Design
Incorporating Human Factors Engineering and Usability Engineering (HFE/UE) processes during medical device development greatly increases the chances that devices will be safe and effective for intended users in the intended use environments and meet the expectations and requirements of regulatory authorities.
The HFE/UE process is frequently viewed simply as a “check-box activity” in the design and development process rather than its foundational component. If HFE/UE is only considered an exercise during the last steps in the design process only to meet regulatory requirements, final human factors validation runs the risk of exposing more serious usability and safety issues requiring expensive redesigns and costly hold-ups rather than merely a last-stage formality in bringing the device to market. These issues delay launches, impact the bottom line, and potentially give competition the upper hand in market acceptance. However, when HFE/UE is prioritized and included at the very beginning of, and throughout, a project’s design and development, it becomes significantly more likely for a design to achieve accolades like “intuitive design,” “easy to use,” or “safe and effective” and to establish the very foundations from which great design is born. Furthermore, it helps design engineers to develop appropriate solutions for the intended users and their use environments earlier because those inputs have been defined clearly (in a Use & User Specification, for example) and incorporate risk control measures to support users in avoiding making mistakes (for instance, in a Use-Related Risk Analysis).
It is in these early stages when time and cost savings opportunities can be found by incorporating and maximizing HFE tools and processes. Usability heuristics are acceptable shortcutting guidelines that can be quickly applied when either actively designing or conducting a usability evaluation. Heuristics are design principles to improve the design and usability of a user interface. Examples of usability heuristics include consistency and standards, visibility of system state, match between system and world, and informative feedback, to name a few. The accepted set of usability heuristics for medical devices was established by Zhang, et al., who successfully modified the heuristics and methodology originally developed by the Nielsen Norman Group for evaluating software interfaces to be applied to medical device design to evaluate safety and efficacy.
At the most basic level, usability heuristics can be applied during early design concepts and used to conduct heuristic evaluations of specific designs. They involve multiple evaluators (usually subject matter experts) who review a design independently of the design team or end-users, and document ways in which the user interface being evaluated violates the heuristics so recommended improvements can be established. These same heuristics can also be used preemptively during the early stages of design and development when identifying use-related hazards and conceptualizing potential design approaches to risk control measures.
HFE/UE and the link to risk management
HFE/UE is often considered just a focus on usability issues when, in fact, it is a fundamental process that informs the development of design inputs and requirements and guides the design direction throughout the development process. Its application should be in partnership with design engineers and product management planners from the very onset of a project.
Regulatory authorities have made their expectations clear that HFE/UE must be integrated into design and development. There is no better exemplar than the statement provided by the FDA regarding HFE/UE, its importance, and connection to managing risks, “The application of knowledge about human behavior, abilities, limitations, and other characteristics of medical device users to the design of medical devices, including mechanical and software-driven user interfaces, systems, tasks, user documentation, and user training to enhance and demonstrate safe and effective use.” And with the recent Draft Guidance for Content of Human Factors Information in Medical Device Marketing Submissions the FDA is again communicating the importance and clear expectations that manufacturers demonstrate safe and effective use by providing a clear link between HFE/UE and risk management activities.
While regulators, like the FDA, provide a definition of HFE that focuses on safety and efficacy and a link to risk management, that is only one side of the proverbial coin that drives a successful product throughout its life cycle. The other side of integrating HFE into design and development focuses on managing project- and business-related risks while also achieving business strategies and objectives to satisfy foreseen or unmet needs in the market. Using HFE/UE tools and processes can be a helpful ally for controlling use-, project-, and business-related risks through early identification and conceptualization, with an increased likelihood of achieving anticipatory, empathetic design solutions that exceed user expectations (the “delight” factor) as well as business goals.
Manufacturers and regulators have the responsibility to ensure that users, use environments, and use-related hazards have been defined and incorporated into a plan for design and development as well as for usability evaluations. To achieve this end, the regulatory authorities, especially the FDA, have made it clear that to do so requires design activities embrace a risk-based approach. This translates to design and development having a tight link between HFE/UE activities and risk-management activities. The proven method for facilitating that linkage and collaboration is to create a Use-Related Risk Analysis (URRA) for defining and tracking use-related hazards and their planned or implemented risk control measures. Specifically, the process involves detailing the use tasks and task steps, user role(s) performing a task step, and characterizations of known or potential use errors to inform the design where risk control measures need to be implemented to meet regulatory expectations and requirements.
Proactive use of heuristics
Once use-related hazards have been identified, preferably at the beginning of the design and development process, then human factors practitioners and design engineers can utilize usability heuristics to assist in their collaboration for generating potentially viable risk control measures for inclusion into the design. Moreover, these heuristics are universally accepted as an efficient, low-cost method for evaluating features related to user and patient safety, as they are cited in the international HFE/UE Standard, ANSI/AAMI/IEC 62366-1:2015+AMD1:2020. Traditionally, a heuristic evaluation is done after a design, or design concepts, have been created/completed to identify potential vulnerabilities and weaknesses, particularly those that could potentially expose users or patients to harmful interactions. However, when used proactively, heuristics can be effective guides for design inputs and potential risk control measure implementation. Such an approach has the potential to provide significant time and cost savings. Another potential benefit to proactively utilizing heuristics is that design concepts are aimed at simplifying user interfaces and interaction touchpoints.
Proactively using heuristics for providing design guidance has the potential to be a high-value, time and cost-effective method used by human factors practitioners and design engineers because it enables an objective set of input guideposts early, especially when implemented before making the significant investments necessary to conduct a simulated-use formative evaluation with representative end-user participants, which are still very much necessary and expected to be completed by regulatory authorities. More importantly, the formal summative validation is still predicated on conducting simulated-use formative evaluations. Nevertheless, proactive application and utilization of heuristics early on can play a key role in empowering development teams to apply generally accepted design principles with increased confidence in providing effective devices that support the user(s)and usability issues and highlight design flaws before major commercial investments are made, thereby optimizing use-, project-, business-, and regulatory-related risks.
The global market demand for innovative, simplified, and safe medical devices is growing at a rapid pace. There is a critical need to apply proven design methodologies that increase the likelihood of meeting or exceeding the expectations of regulators to smooth the path to market launch. One of the best ways to become that “early bird” with your design is to reinvent an older, nearly forgotten tool in the HFE toolbox — proactive use of usability heuristics. These design guideposts have never let me down, and I’m confident that, if deployed correctly, they will do the same for your design.
Sources Zhang, J., Johnson, T. R., Patel, V. L., Paige, D. L., & Kubose, T. (2003b). Using usability heuristics to evaluate patient safety of medical devices. Journal of Biomedical Informatics, 36(1–2), 23–30. https://doi.org/10.1016/s1532-0464(03)00060-1  World Leaders in Research-Based User Experience. (n.d.). 10 usability heuristics for user interface design. Nielsen Norman Group. https://www.nngroup.com/articles/ten-usability-heuristics/  Center for Devices and Radiological Health. (n.d.-b). Human factors and usability engineering to medical devices. U.S. Food and Drug Administration. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/applying-human-factors-and-usability-engineering-medical-devices  Center for Devices and Radiological Health. (n.d.). Content of HF information in medical device marketing submissions. U.S. Food and Drug Administration. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/content-human-factors-information-medical-device-marketing-submissions
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