Navigating the FDA can be a long and cumbersome process, but the FDA’s 2011 Draft Guidance for Human Factors Engineering clearly states that the FDA truly wants to help you make a medical device that will be safe and profitable in the long run. The Draft Guidance includes recommendations, not mandatory tasks, for the human factors process. Though technically not necessarily mandatory, industry and government alike have come to agree that Usability Engineering is essential if you want your device to be safe, profitable, and well-received by customers. Refer to UserWise’s Usability Engineering 101 for an outline of the process.
In creating a device, the best way to prevent use-related hazards is to perform user research, conduct task analyses, assess hazard-related use scenarios in detail, and to perform iterative usability testing In the past, many manufacturers would only focus on the product’s device-related hazards and ensure that the device, as designed, functioned. Today, usability engineers actively search for detrimental effects that may arise when a person tries to use the device, even if the device may appear to function as it should. Modern usability engineering programs in medical device companies include observation of device use early in a product’s development to identify issues that occur in different environments and situations. A more detailed description of the Usability Engineering process, which summarizes key points from the Draft Guidance, is below.
First, identify the appropriate user groups in order to know who to include as participants in usability studies. Users range extensively for various medical devices, including surgeons, healthcare providers, patients, family members, individuals who clean the device after it’s been used, or a combination thereof. It is essential to record how much training the user has had with the device before using it and the user’s personal characteristics (e.g. physical strength, cognitive ability, etc.).
Next, identify the use environment(s) (e.g. OR room, mass casualty event, home, etc.). Take note of factors like low lighting, noise level, crowded rooms, and pets. Furthermore, pay attention to the device’s interoperability with other devices.
Then take into account how similar devices on the market work. For example, all bottle caps rotate clockwise to close. You would not make a cap that closes by rotating counterclockwise. After, observe the target users, possibly while using a similar device, in the appropriate environment. Pay attention to their actions and body language to find where they may have difficulties.
Your goal should be to find the use-related hazards as early as possible in order to reduce cost and expedite bringing the device to market. When a use error is uncovered, assess the likelihood and severity in a use-related risk analysis.
To go about finding use-related hazards, first identify what the use-related hazards could be analytically. You can look at the safety information available on similar, pre-existing devices. Good resources include FDA’s MAUDE website and online customer reviews. Sales staff are also an excellent resource as they frequently understand customer issues. Additionally, you will want to cover all relevant topics related to the new device by performing one-on-one interviews to observe and question users as they indicate how they would use the device. You can also gather more information using focus groups (a group of more than one person). These are generally not recommended, however, because of the “waterfall effect” (where one alpha individual influences the thinking of the rest of the participants) which may skew results.
Next create a task analysis by identifying a list of tasks and highlighting the ones that are performed by the user. Make note of the interdependency between each task and what happens if a user performs them in a different sequence. Then go through the possible hazards, based on previous research, at each specific step. Determine the severity and frequency of each in order to pinpoint which risks need to be minimized and to prioritize the critical risks. Pay special attention to the rare hazards with serious consequences. Those can cause the most harm because users may not be properly prepared for them.
Make sure to incorporate all information into a use-related risk analysis for the FDA. This analysis should be expected to be revised through different iterations of prototypes and usability testing as new use errors are uncovered.
The end product may still have some residual risk. It is important to prove that there is no way to minimize these risks further, and that the benefit of having the device on the market outweighs the risks. The key question here is “would you want your friends and family to use this device?”
Iterative Prototyping and Usability Testing
Your goal of iterative prototyping and usability testing is to identify and reduce risks. Ways to reduce risk include changing the design itself or adding labeling and instructions for use. Identify all features of the user interface, which is everything the user interacts with before, during, and after using the device (e.g. instructions for use, alarms, buttons, touch screen, etc.). Incorporate these features into models used for mock-ups and prototypes.
In usability testing, researchers can use simple mock-ups of the device, prototypes, and other features of the device like manuals. Mock-ups will evolve into more refined prototypes, each time addressing specific high-risk use-related issues identified in the original risk analysis or previous user testing.
Design and test the product based on the identified users, use environment, and user interface. For early usability testing with low-fidelity prototypes, researchers can walk participants through the use of the product, asking the user questions at each step. The goal is to obtain a better understanding of the user’s mental process and opinions without having to invest in a high-fidelity prototype. Later on, users can be tested in a more realistic manner by providing them with the appropriate level of training and then asking them to use the device.
When use-related difficulties and use errors are observed during this early-stage usability testing, design a next iteration of the prototype/mock-up to address the issue. After each usability study, make sure to update the use-related risk analysis to inform changes to the next iteration of the device.
Usability validation is a usability study including the final production equivalent product configuration. At least 15 users (25 in the case of infusion pumps) of each user type perform all critical tasks identified in the task analysis. Typically, the test takes place in a simulated use environment. Your goal is to demonstrate that the device has no points of failure that could be improved and that the benefits of the device outweigh any risks.
Furthermore, it is important to take into account training decay. For example, if a user will learn how to use the device three months before actually using it, the user will most likely forget much of the training. Therefore, in usability testing, it is important to simulate this period of training decay in as realistic a manner as reasonable.
In rare cases, clinical usability validation is required. In clinical usability validation, the device is tested in a real life scenario. For example, one would actually administer a drug using an injection pen, instead of mimicking the process.
Human Factors Submission and Compliance
A Human Factors Submission should include the descriptions of the users, purposes of the device, use environments, training, device user interface, known use problems, task analysis, and usability testing and validation. Refer to UserWise’s HFE Submission Checklist for more information. Remember to keep all documentation in a file, even that which is not submitted to the FDA. The goal of including a human factors submission in the report to the FDA is to minimize FDA questions about usability and safety, and to expedite the pre-market approval process.
(Interested in how this 2011 version of the FDA Draft Guidance compares to its 2000 predecessor? What about how it compares to the international guidance, ANSI/AAMI/IEC 62366-1:2015?)
"Draft Guidance for Food and Drug Administration Staff: Applying Human Factors and Usability Engineering to Optimize Medical Device Design." U.S. Food and Drug Administration: Protecting and Promoting Your Health. U.S. Department of Health and Human Services, 22 June 2011. Web. 13 Aug. 2015. <http://www.fda.gov/downloads/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/UCM259760.pdf>.