All medical device companies perform human factors engineering (HFE) in some capacity. Human factors validation often is required for a medical product to reach market. The type of human factors validation that each device undergoes can be based on the medical device regulatory risk classification, severity of harm associated with the use of the device, or product complexity.
Some companies treat the human factors validation process as a check box at the end of product development rather than using the HFE process throughout the product life cycle, which can lead to costly validation tests that generate a multitude of usability issues that need to be fixed, thereby delaying timelines and launch dates and harming a company's bottom line.
Companies that incorporate a robust HFE process into the entire product life cycle find that they have increased product safety and decreased development time. It also results in a competitive advantage in the marketplace. This article provides an overview and introduction to what a robust HFE process looks like.
What is HFE for medical devices?
A common misconception of HFE is that the focus is solely on usability of a device. This may be true in consumer products; however, in the medical device industry, the priority is patient and health professional safety, as well as device effectiveness. The Food and Drug Administration (FDA) describes HFE as1 :
“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. Human Factors Engineering and Usability Engineering can be considered to be synonymous.”
The main objectives of HFE are primarily used as a risk management tool to:
If the above points are accomplished within a robust HFE process, it has the added benefit of:
Increasing the device ease of use.
Making the product more desirable to use.
Lowering support costs and complaints.
Reducing development rework.
Speeding up time to market.
Ultimately, each of these qualities increase sales and revenue.
As an example, consider how a device's power button location can be designed with different safety principles to reduce patient risk. A power button on a consumer electronic device typically is placed in an easy-to-find and easy-to-operate location, in order improve ease of access. In contrast, a power button on a medical device might be placed in the back, in a lower, harder-to-reach corner, which clearly is not user friendly. This is to avoid accidental shut down. In this situation, the risk to the patient of a medical device being accidently powered down during use outweighs the benefit of ease of use for the operator of the device.
What is a robust HFE process?
HFE is an essential part of the product development life cycle and should be prioritized and embedded into each phase. A robust HFE process should be:
Ongoing. The process is not a one-time test that finds all design flaws.
Measurable. The process should include metrics that are defined and observable so that improvements to the product and return on investment are measurable.
Iterative. Testing and designing is iterative, in order to refine design and usability and therefore increase safety.
Integrated. The HFE process should be integrated into product development. This is key to ensuring that data-driven design decisions are made throughout the development life cycle. At least one HFE deliverable should occur during each phase of the development life cycle.
A common mistake made by companies is completing work on an entire product, then taking it directly to an HFE validation test without any previous HFE activities. By waiting until the end to test the safety and usability of a product, the chances of finding high-risk use errors increases and does not allow changes in the design to be easily made without affecting the project schedule and/or budget. Therefore, one often hears the question, “What if we fail our HFE validation test? We don't have time to make any changes. What will we do then?”
Product teams that have been proactively evaluating HFE early and often in the product development cycle and incorporating the feedback from each study into the design of the product will reduce the likelihood of failing an HFE validation test because they already will have found the high-risk use errors and had the opportunity to mitigate them with design changes. When the production-equivalent product is taken to its final HFE validation test, the team can be confident that it will perform as designed and that any residual risks have been mitigated.
How does one make a process robust?
To have a robust HFE program, all team members on a product team need to understand what a human factors engineer can contribute to the product development process. This will allow the team to allocate sufficient time in the schedule and budget for HFE activities. Although not all team members are responsible for schedules and budgets, ensuring that everyone has a basic understanding of the HFE process allows team members to advocate for sufficient time for HFE activities in their teams or during meetings where HFE might not be represented (as is often the case in smaller companies).
Writing Human Factors Plans & Reports provides the foundation for developing specific human factors engineering (HFE) work products that are needed to meet the FDA's human factors engineering (HFE) guidance. The authors have created a fictitious company and product to generate concrete examples of the plans and reports developed during various stages of HFE. The book includes an HFE project plan, a formative usability test plan and report, a summative (i.e., validation) usability test plan and report, and an HFE report. These work products and additional content outline the activities necessary to develop safe and effective medical devices, making this book an ideal resource for anyone interested in the medical technology field.
Available in the AAMI Store at bit.ly/3pleJpy.
Human factor activities can include user research, task analysis, heuristic evaluations, formative testing, expert reviews, and ergonomic assessments.
Start with Awareness, Education, and Company Culture
One of the authors (T.D.) created an HFE division at a medical device company. During this process, it became clear that the best way to integrate HFE into both the culture and process was to educate employees from all functional areas about the definition and value of HFE.
An HFE awareness training module was incorporated into the product development process training. This training is now required for all employees who are involved in product development. After it was added to the training, within five months, 513 individuals spanning the U.K., U.S., and Singapore were educated on HFE—its activities, its deliverables, and where it fits into each stage of the process.
At that time, the company had 5,000 employees, which meant that 10% of employees had been made aware of HFE and its benefits. These individuals came from a variety of functional areas, including research and development (R&D), marketing, customer support, electrical engineering, quality, mechanical engineering, product management, and core team leads. As a result, educated staff knew to involve the HFE team early in a project in order to allow for sufficient iteration of a product.
Add Strong Documentation
Strong and well-documented HFE activities will drive design decisions and ensure that one is testing and reducing the risk of critical device tasks. Documentation takes time and needs to be implemented into the document control process. The documents produced by the HFE team will be incorporated into the design history file (DHF), demonstrating proper design controls and traceability of design inputs and outputs. Lastly, documentation of the HFE process is required by many regulatory bodies for medical device approval.
HFE documentation and information can include:
Use specifications.
User interface specifications.
Task analysis.
User needs.
Expert reviews.
Heuristic evaluations.
This information is important and can feed into:
Traceability matrices for design decisions.
Patents.
Product redesign.
Proof of successful risk mitigations (as they pertain to critical tasks and product safety).
Using standardized document templates for this information will improve the robustness of one's process. Examples of these templates may include:
Exploratory research plan and report.
Formative test plan and report.
Task analysis.
HFE plan and report.
HFE validation test plan and report.
Postmarket surveillance research and reports.
Thorough documentation is required by regulatory bodies. From a regulatory perspective, “If it's not documented, it didn't happen.” This is true especially when it comes to updating risk management files, documenting design traceability, creating the DHF, and submitting to regulatory bodies for approval.
Strong documentation helps keep tasks on track, teams aligned, and expectations clear. Various documents will emerge at different points in the product development process. For a detailed graphic of the deliverables within the product development process, refer to the AAMI technical information report TIR59:2017, Integrating human factors into design controls. The diagram in TIR59 outlines where each deliverable occurs in the development life cycle (Figure 1).4
Design controls and human factors (HF) engineering/use environment (UE) activity mapping.4 Abbreviations used: FDA, Food and Drug Administration; UI, user interface. Image copyrighted 2017 by AAMI. Used with permission.
Design controls and human factors (HF) engineering/use environment (UE) activity mapping.4 Abbreviations used: FDA, Food and Drug Administration; UI, user interface. Image copyrighted 2017 by AAMI. Used with permission.
To set up a documentation process that will support a robust HFE process, gaining buy-in from everyone who will be contributing to and using the final documents as inputs for their deliverables is important.
For example, an HFE validation test plan usually requires input from risk management, quality engineering, medical affairs, R&D, and regulatory to ensure that the plan has buy-in and everyone is invested in the success of the study. Examples of the inputs of these roles include the following:
Risk management helps to ensure that the plan includes proper verbiage to trace what is being tested mapped to its risk management documentation.
Quality engineering helps to ensure that the plan uses verbiage consistent with standards and guidelines.
Medical affairs contributes to portions of the plan pertaining to product background and use environments and defines how detailed task scenarios needs to be added, including creation of testing artifacts for the studies.
R&D contributes guidelines on how technical details about the product should be written and shared to ensure technical accuracy.
Regulatory helps to ensure that the proper guidance documents is cited.
Add Strong Team Members
The last component of achieving a robust HFE process is building a diverse team with a wide range of expertise to support team members in accomplishing their tasks. Doing this requires established internal processes to:
Hire both senior and junior degreed human factors engineers.
Successfully onboarding new employees so that they are knowledgeable of their team members, understand how they fit into the HFE process, and have access to the documentation and tools needed to succeed.
Train employees on product offerings.
Support employees in ongoing training and growth. External training offered by AAMI is beneficial to all employees working as or with a human factors engineer, even if the human factors engineer on the project has ample experience. Medical device HFE is a specialized skill that must be treated as such.
Support nontraditional HFE employees in obtaining training. On-the-job experience, along with external exposure to HFE conferences, can help develop employees from other areas of the company into usability specialists. Moving the head count from one area of the organization to HFE has benefits, including expanding knowledge of product, people, and process within the company.
A robust HFE team should include experts who have formal degrees in HFE, as well as junior individual contributors who can be trained and given opportunities to grow within the company. This ensures that when experts leave, the process is passed down and maintained.
Successful onboarding of employees can be done in many ways, but the goal should be to train incoming employees on products and company processes to allow them to function as independently and quickly as possible. Organizations should consider creating a standardized 30-/60-/90-day plan to which employees can adhere, as well as scheduling meetings with various stakeholders. Exposing new hires to product demonstrations early will help with overall understanding of the intended users, intended use environment, and expected use of a product.
Further, all employees, regardless of experience level, should be given the opportunity to attend training and conferences. Medical device requirements and regulatory body interpretation of those requirements continue to evolve, and continuing education allows employees to stay up to date on the most current requirements and interpretations. Giving employees the opportunity to gain expertise brings attention to the HFE team and can attract talented professionals to the company.
In many cases, employees who have not been formally educated in human factors will wish to pursue an HFE degree. This is another way to increase the competency of the team and helps build a more robust process. These employees will benefit from formalizing their knowledge, as well as build valuable industry connections. This enables mentoring of other employees who do not have a formal HFE degree.
Conclusion
HFE processes provide maximum benefit when integrated into the existing product development process parallel to other product development functions. Ideally, HFE is applied throughout the development process, starting with predesign control activities. However, even if a project is in its later stages, including analysis at that time, rather than not at all, is preferred.
Releasing a product without due consideration for HFE could lead to the injury or death of a patient or health professional. Poor attention to HFE can drive business away to competitors, thereby damaging a company's bottom line. HFE activities provide for a better user experience and safer outcomes, which ultimately is good for business.