Reducing Medical Device Risk with Usability Testing: The Why, the How, and the Who

What are the product’s intended uses?

  • What’s the intended use? How and in what circumstance should the product be used? What is the intended medical indication the product is meant to treat?

  • Are patients using the product to self-treat? Could there be any physical limitations that prevent a certain patient from interacting with your product as intended?

  • Is training required? What level of training is required, if necessary? (We highly recommend training be kept front of mind throughout the development process.)

  • What is the user interface of the product? This includes all points of interaction — physical and digital — between the user and the device.

In what use environment is the product being deployed?

  • Is the product intended to be used exclusively in the home by a patient? In an emergency room or ambulance?

  • Does the product use differ, depending on the environment of use? Whether the user is in an adult ICU, a NICU, or in an ER trauma bay — each of these contributes to significant differences in the way a product is used.

From a regulatory standpoint, the FDA will be looking to see that all elements of the users, uses, and use environments have been researched and incorporated into the plan for conducting proper usability testing in the relevant simulated-use environment with the intended users and uses.

The ideal process might include multiple rounds of formative usability testing, which can be used to inform a Use Failure Mode and Effects Analysis (uFMEA). As you go through the cyclical design process — adding design inputs, testing them, refining, then adding more design inputs — you’ll eventually reach a point where you’re comfortable with the product you’ve created.

A final production-equivalent medical device should be put through validation, or summative, testing, to assess whether or not the product can be deemed safe and effective to use.

2. Assess! Create a Use Failure Mode and Effects Analysis (uFMEA)

A uFMEA assessment is meant to identify components of the user interface and the impact of task failures. What are the possible failures that could occur? Why would these failures occur? What are the consequences of the failure and what’s the associated harm?

Start by creating a step-by-step list of all tasks, required to accomplish the device’s end goals. (Tasks are defined as the action or set of actions performed by a user to achieve a specific goal.)

The uFMEA also notes what could go wrong if any of these tasks are not completed correctly. To help determine this, go through a PCA (perception, cognition, action) analysis process

As your team goes about defining tasks, determining failure modes, and assigning levels of severity of harm, you may next want begin to categorize your tasks as critical versus non-critical. 

Critical tasks are those which, if performed incorrectly or not performed at all, could cause serious harm to the patient or user where harm is defined to include compromised medical care. 

User tasks are often tied to product requirements, and usability testing (formative and validation) will be needed to prove these user needs have been met.

Finally, when developing your product’s uFMEA, make sure your team has thought through the level of mitigation that will, ultimately, be required by the IFU and labeling within the context of intended use. During this process, you may also come to a point where you recognize whether or not your product will require some level of training.

Be diligent about identifying all potential use errors and outcomes before getting into validation or even pre-validation testing. Be as clear as possible about what could go wrong and what needs to go right in order to merit a task has been completed successfully. These success criteria will feed into a task analysis table that will define what needs to be tested from a usability standpoint.

And finally, keep in mind that a uFMEA should be treated as a living, breathing document that evolves as the product progresses through the design process. Expect it to change as the device goes through rounds of formative usability testing, is put in the hands of users, and as the design team gains a better understanding of how the product can and should be used.

3. Research! Use These Three Approaches To Usability Testing

There are three usability testing approaches to consider:

  • Rapid Insight Testing

  • Formative Testing

  • Validation Testing

Rapid Insight Testing may be appropriate if all that’s needed is a quick touch-base to keep the design grounded in user needs. Roughly five to six participants are recommended, but it’s possible to test fewer in certain situations. This type of testing typically occurs prior to entering design control.

We recommend conducting Rapid Insight Testing on all elements of the product, including human factors. Sample questions are: How did it feel to use or handle the product? Is the grip intuitive or did someone need to show me how to grip it? Are we testing all of the possible users of the product or are there others that could be seen as a potential user?

This is your opportunity to evaluate all tasks, not just the critical ones. Additionally, this is your chance to get as much subjective feedback on the product as possible! What are their preferences? What are they used to seeing and what would they like to see changed?

Formative Testing begins to inform the design process. Anywhere from five to ten representative users per user group are recommended and aim to simulate the use of the product in the simulated use environment with a high-fidelity prototype. We suggest conducting a minimum of two to three rounds of formative testing during a product development cycle. This is what’s going to lead to product design change mitigations, which is ideal — better now than later! Design changes are hugely preferable to changing labeling or instructions-for-use (IFU) late in the game.

Validation testing is required by regulatory bodies in the U.S. and Europe, and elsewhere around the world. At this stage, testing with a production-equivalent product is expected, and when dealing with FDA, 15 representative users per user group is required, as is representative simulated use in the simulated environment.

It’s important to note that once you’ve reached validation testing, only critical user tasks should be evaluated, so it is important to evaluate all non-essential user tasks earlier in the process via rapid insight and formative testing.

4. Comply! Resources and Tips for Regulatory Consistency

A long discussion could be had when it comes to regulatory compliance, but here are a few resources, tips, and misconceptions to keep in mind.