Your Medical Device Is Not Ready for a Human Factors Validation Study Until You Complete These 4 Steps

 In Human Factors & Usability Testing, Medical Product Design

A human factors validation study is conducted to demonstrate that your medical device can be used by its intended users without serious use errors or problems. It’s required testing for most products as they’re finalized — before they go to market. And its results must be included with your finished FDA submission.

If your human factors validation study is inadequate, the FDA can bounce your entire submission back. Consequently forcing you to redo your human factors validation study — or worse, your actual design — and resubmit it for another chance at FDA approval.

Needless to say, the stakes are high. To make certain it’s the right time for your human factors validation study, ask yourself the following:

  • Is my medical device ready for real-world use — without harming users or compromising care?

  • If there are risks associated with my product, are they sufficiently mitigated?

If you’re finding it at all difficult to answer these questions, or if you simply want to confirm your product’s suspected readiness, read on. We’re sharing four key areas to assess before heading into human factors validation testing, including what to do if you discover your product isn’t quite as ready as you thought.

Check Off These 4 Tasks Before Moving Forward With Your Human Factors Validation Study

1. Your Identified User Groups Are Comprehensive

Ideally, you will have identified user groups at the beginning of your medical device development journey and updated them throughout the process as necessary. But that doesn’t always happen. Instead, there’s a tendency to treat documenting user groups as a rote to-do on a checklist when in reality user groups contain a lot of nuance. And capturing them comprehensively is anything but rote.

For example, imagine you’re developing a home-use medical device for men. You record your user group as, simply, “men between the ages of 25 and 75.” That’s far too broad for a single user group. Just consider the potential dexterity issues of a 75-year-old versus a 25-year-old. Your design might need to adapt for an elderly user, so you should further segment your users into multiple groups. That could look like grouping your users by age range, i.e., young adult, mid-adult, elderly adult.

Your user group descriptions — contained in your use specification document — must take the personal, specific characteristics of your multiple intended user groups into account. Further, as in our example, you should analyze how those characteristics might impact the user’s operation of your product. Your use specification should also detail the level of training users are expected to receive.

Identifying user groups is admittedly more straightforward for some medical devices than others. That’s because industry user groups are more established for certain kinds of products, such as ventilators and RTs.

If you’re creating a home-use device and the main user group is laypeople, you’ll have to wade through a lot more nuance that will inevitably impact user interactions with your device in additional ways. That’s because the behavior of the average person is generally less predictable and more varied than that of a physician who’s accustomed to operating a range of medical devices regularly.

Shore Up Your User Groups

No matter what kinds of users you’re dealing with, if you find your user groups lack detail, you need to critically evaluate them before your human factors validation study. You can begin to do so by reviewing user groups for similar on-market medical devices.

It’s important to involve a human factors specialist in this exercise. Thanks to their experience with diverse healthcare industry clients, they’ll likely bring user characteristics to light that you hadn’t considered (e.g., physical and/or cognitive traits).

2. You Conducted Usability Evaluations With Representative End Users

You should strive to complete usability evaluations during different stages of your medical device’s design. After all, you simply don’t know what your users are going to do with your product until you see them using it for yourself. And you certainly don’t want to be surprised by user behavior during your human factors validation study.

You won’t submit any of these formative tests to the FDA like you will with your human factors validation study results of course, but the findings from early usability evaluations will help your team:

  • Identify realistic use errors and potential outcomes based on what you observe users doing.

  • Modify your design (including your user interface design) so that use errors stemming from a design issue no longer occur or occur less frequently.

  • Keep a transparent record of the design modifications you’ve made to mitigate use-related risks.

If you haven’t conducted sufficient usability testing, you still have a couple of options to fill in any usability gaps prior to your official human factors validation study:

Conduct a Heuristic Evaluation

FDA guidance defines human factors usability evaluations (HFE/UE) as:

A process in which analysts (typically HFE/UE specialists) evaluate a device’s user interface (UI) against UI design principles, rules, or “heuristic” guidelines to evaluate the UI overall and identify possible weaknesses in the design, especially when use error could lead to harm.

During this process, an HFE specialist would take your market-ready device and its Instructions for Use (IFU) and evaluate them against industry guidelines to identify where your device has possible design weaknesses. If there’s required training for your medical device, this process would also include that expected product training.

The result is information you can leverage to improve your medical device design before it goes up against your official human factors validation study.

Conduct Simulated Use Formative Usability Testing

Formative testing can serve as a dry run or pilot test for the real-deal: a human factors validation study. You’ll get a better idea of what to expect without the pressure to submit your results to the FDA.

Methods for formative testing involve observing representative users performing a product’s intended uses. You’ll have sensitive and specific measures in place to flag inadequacies or flaws with your UI design that could impact safe and effective device use. Ideally, you’ll be watching users in the intended use environment operating the whole system. When you complete this kind of formative test, you avoid surprises during your human factors validation study.

3. Your Risk Analysis Considers Risks, Hazards, and Harms Resulting From Use Errors

The FDA’s ultimate goal is to ensure your medical device is safe and effective for your end users. That’s what they’ll look for in your submission, which includes your human factors validation study. All that to say, getting your risk assessment right matters.

A high-quality risk assessment captures every potential hazard associated with your medical device. That includes use-related risk analysis from a use error perspective. Too many risk assessments focus on device failures and neglect use errors. But it’s just as important to consider where users could go wrong. After all, people can and will make mistakes operating your product. And the FDA reminds us that the most effective way to mitigate risks is to build safety by design.

A use Failure Modes and Effects Analysis (uFMEA) is one tool that has the ability to detect use-related hazards and their mitigations. If it’s completed effectively, the uFMEA should capture all hazardous situations such that if a situation is possible, you can point to it in the document and see what the worst outcome would be.

Your human factors partner will appreciate a robust uFMEA as it’s an important reference point during human factors validation study preparation.

Leverage a TURRA

We’ve established that your uFMEA is critical to adequate risk documentation. But what if your uFMEA isn’t up to par? Or your risk analysis in general is lacking?

You can complete a TURRA — a task and use-related risk analysis. A TURRA is a bottom-up approach to risk management that ensures you’re considering all possible outcomes from a user perspective. It helpfully feeds into your uFMEA and list of hazardous use scenarios.

The high-level steps of a TURRA include:

  • Capturing the entire user workflow end-to-end by identifying the user’s goals and decomposing them until you have concrete steps that describe the user’s interactions with your system

  • Considering what could go wrong at each step from the user’s perspective

  • Assessing the potential use errors against your risk strategy to evaluate potential outcomes and the severity of the risk

A rigorous TURRA based on these steps tells the whole story of potential patient or user harms, thus bolstering your human factors validation study for FDA submission.

4. Your Device Is Market-Ready

Last but not least, a human factors validation study-ready medical device is also market ready. In other words, your commercial-equivalent device is complete before you embark on testing for FDA submission.

Since human factors validation centers on evaluating the entire UI to demonstrate how it will support users in achieving safe and effective use of your product, the design you present for your human factors validation study must be final. That means:

Review Your Project Timelines

To ensure your medical device is market ready by the time your human factors validation study approaches, review your project timeline to pinpoint project constraints and milestones.

Preparing for your human factors validation study requires at least one to two months of lead time. Speaking with a human factors expert can help you understand how to meet your milestones without jeopardizing the quality of your human factors validation study.

An FDA-Worthy Product Awaits

Satisfied investors, an impressive product, an in-tact production timeline — so much rides on a successful FDA submission. And a successful FDA submission relies on an excellent human factors validation study. With the four key areas covered here in mind, you can either confirm you’re set for your study or complete the related to-dos to get your product ready.


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