April 11, 2012

8 Min Read
Usability Also Applies to FDA Submissions: Adventures in Medical Device Usability

Eventually, I’ll have something to say about device usability. This time, though, I want to talk about something else—the usability of FDA submissions. Most of the people working on medical devices have gotten the message that medical devices need to be reasonably easy to use, at least far as ease-of-use relates to safety. It follows that it’s necessary to apply a methodology:


Stephen B. Wilcox, Ph.D., FIDSA

  1. Studying how devices are used under real-world circumstances (i.e., contextual inquiry). 

  2.  Applying technical information about users, both “physical human factors data”, like hand sizes and strength data, and “cognitive human factors data” like information about what is and isn’t easy to remember. 

  3. Conducting iterative usability testing to identify use errors, so they can be eliminated.


And so on.


The question I want to ask: Why shouldn’t this methodology for achieving usability  also be applied to FDA submissions? After all, submissions are products that are used by actual human beings, just as medical devices are. At least when it comes to usability, the key people are in the Office of Device Evaluation in the Center for Devices and Radiological Health (the ODE of CDRH). They’re collectively called the “Human Factors Premarket Evaluation Team.” Here’s how their job is described on the FDA Web site:


The purpose of the FDA’s Human Factors Pre-Market Evaluation Team is to ensure that new medical devices have been designed to be reasonably safe and effective when used by the intended user populations. The effort primarily involves reviewing new device submissions, promoting effective and focused human factors evaluation and good design practices for medical devices.


Let me refer to them as the HF Team.


For FDA submissions, we can’t actually study the users in their natural environments, and we can’t really do traditional usability testing (Items 1 and 3 above), unless you consider making a submission itself a type of usability test, with approval being the measure. However, we can apply principles of human factors (Item 2) to our submissions. In this particular case, our task is made easier because the HF Team has told us how to put together an “HFE/UE report” (i.e., a human factors engineering/usability engineering report) in Appendix A of the Draft Guidance for Industry and Food and Drug Administration Staff: Applying Human Factors and Usability Engineering to Optimize Medical Device Design, issued in June, 2011. The HF Team provides chapter and verse of what should be in a report. It describes seven sections and goes into a fair amount of detail regarding what should be in each section.


So, the first human factors principle to apply to your FDA submission is:


  • Don’t violate the user’s expectations. 


And, as I mentioned, because of the Draft Guidance, we know what the users’ expectations are. 


Some other principles (and I take responsibility for these; I don’t mean to imply that they come from the HF Team) are also important.


Use images where it will help comprehension.

Some things can be easily communicated in images that would take hundreds of words to express and, even then, still be difficult to comprehend (think about a road map, for example). Potential examples are the overall structure of the HFE/UE program and how it fits into device development, the device itself along with details of displays and controls, navigational structures and screens for software-driven devices, packaging details, icons, and the testing setup for the actual validation research. This isn’t an exhaustive list. Research has consistently shown that documents combing words and pictures result in better understanding that documents with only one or the other.

Allow for efficiency of use.

Longer is not necessarily better. In fact, it’s often much worse, particularly when there’s a lot that the reviewer doesn’t want or need.

Don’t force the user to interrupt the flow of a procedure.

It’s good to avoid constant references to other documents that have to be tracked down in order to follow the logic of a report. Such references are fine, and often necessary, but the body of the report should be sufficient for the reviewer to make decisions, so that the other documents serve only as appendices, to be consulted in special cases.

Avoid jargon unless you’re absolutely sure the user is familiar with it.

Don’t assume that the reviewer will understand acronyms just because you and your colleagues use them every day.

Create an intuitive information hierarchy.

The document should have a clear, intuitive structure that allows the reviewer to easily go from one section to another and to find a particular topic of interest.

Be consistent.

One of the easiest ways to create confusion is to be inconsistent with a document’s structure, terms that are used, etc.

Make sure the form mirrors the content.

Any change in form (e.g., in typefaces, colors, spacing, indentation) should reflect a change in content.

Use real-world metaphors to take advantage of previous knowledge.

This suggestion particularly applies when a new device is very different from what came before.


The basic idea is to take a “user-centered” approach; the key for all user-centered design is to look at it from the point of view of the users, who are inevitably quite different from the designers. In this case, the users don’t live and breathe your devices, and they don’t live and breathe your design processes, like you do. Submissions reviewers are motivated to make sure that patients aren’t harmed, not to make sure that R&D dollars pay off (although I’m confident that, within the constraint of protecting patients, they’re all for companies making profits). What you probably have in common with the HF Team is an incredibly heavy workload. So, like you, they appreciate anything that allows them to do their jobs more efficiently, and this is where the usability of submissions fits in.


I certainly don’t claim that a more usable submission is more likely to win approval (Lord knows, things like that are not for me to say), but I can’t imagine it would hurt, and I would expect it to at least save time. And, in the ensemble, saving time at FDA should logically lead to shorter review periods, which would help all of us.


Let me just say in closing that (and here I may shock you) I’m not one of those who rails about the evils of regulation in the medical device industry. One of the themes we heard in the presidential debates is that the US medical device industry (along with the rest of America) is at risk of being destroyed by “overregulation”—that, now we’re giving an advantage to OUS competitors. However, call me an idiot, but I can’t see how making it a little tougher in the US market doesn’t actually help US industry by stimulating more US exports (if indeed it’s easier to gain approval OUS) and making it harder for OUS companies, who are likely to be less adept at navigating US regulations, to compete in the US marketplace. 


Now, I admit to being biased. After all, how can you dislike people who force the world to take your discipline seriously? We’re all better off with tougher, but more consistent usability-related regulations. From where I sit, FDA does, in fact, make patients safer, and by improving regulatory consistency, they make the whole approval process much more predictable (frankly, it used to feel like a crap shoot). And they give an advantage to the responsible companies, who were already developing devices with good systems in place, relative to the corner cutters, who used to have the competitive advantage of lower R&D costs.


The folks at FDA are hard working, dedicated professionals who are truly motivated to make sure that devices are safe and effective. I actually think its rather refreshing to find people who really are trying to do the right thing (even when it makes their jobs harder) in a world where the nightly news gives us daily evidence of venality in just about every sector of society. Those of you who want to “starve the beast” can count me out, at least when it comes to FDA.


Sorry, I got a little political, didn’t I? I promise it won’t happen again.


Stephen B. Wilcox, is a principal and the founder of Design Science (Philadelphia), a 25-person firm that specializes in optimizing the human interface of products—particularly medical devices. Wilcox is a member of the Industrial Designers Society of America’s (IDSA) Academy of Fellows. He has served as a vice president and member of the IDSA Board of Directors, and for several years was chair of the IDSA Human Factors Professional Interest Section. He also serves on the human engineering committee of the Association for the Advancement of Medical Instrumentation (AAMI), which has produced the HE 74 and HE 75 Human Factors standards for medical devices.

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