3 crucial aspects of submitting a successful human factors engineering package to the FDA

April 12, 2023

Have a mid-development question about medtech regulation? Chances are – no matter the size or scale of the manufacturer you work for – you probably can’t just pick up the phone and ask the FDA for an answer. Most often, the process is instead slow and bureaucratic, which can make it all seem not worth the effort.

But you still have a question. And manufacturing a successful product depends on an answer.

Luckily, while the compliance concerns governing human factors research and medtech manufacturing have been revised throughout the years, there’s a consistent throughline: the architecture of the guidance and its goals has never really changed.

In this blog, we’ll cover three crucial aspects of submitting a successful human factors engineering (HFE) package to the FDA.

Identify all use-related risks

From regulatory documents to conference presentations, the FDA has over the years offered fairly clear and consistent guidance about use-related risks. Whether discussing medical devices or combination products, the gist is generally the same.

The most concise way I’ve heard this guidance described? “Know, Control, Show”:

  1. Know your product (i.e., identify use related risks).
  2. Control for use-related risks (and test those controls).
  3. Show that the residual use-related risks are outweighed by the clinical benefits.

With this in mind, the first step of creating a successful human factors engineering package is to demonstrate that you’ve identified all of the risks associated with how that product will be used.

It can be helpful to start by answering questions such as:

  • Who are the intended users?
  • What are the intended use environments?
  • How will those combine with the context of use to enhance, complicate, or compliment the ways in which your product is used?

As an example, let’s consider an epinephrine auto-injector like the EpiPen. Auto-injectors work by a spring or other mechanism that, when triggered by the user, pushes on a plunger and expels the drug through a needle into the patient. The user doesn’t have to push the drug out of the device like in a syringe; the device does the work for them.

No matter who the user is, the context of use presents a risk: EpiPens are meant to stop anaphylactic shock and so are typically used in high-stress scenarios by people experiencing panic, which can impact both cognition and motor function.

If the user is also the patient, physical impairments associated with anaphylaxis, like trouble breathing, along with the panic that often accompanies an anaphylactic event, may impede the patient’s ability to successfully administer their dose.

And there are separate potential use-related risks for users who aren’t the patient. Say the user is a friend or bystander who’s never used an EpiPen before – they’re simply trying to help. The problem? To people who haven’t been trained how to use an EpiPen, both ends of the device look similar.

The result: that good samaritan may accidentally inject their thumb rather than the person undergoing the allergic reaction. Yes, there are instructions printed on the side of the device. But this user is probably panicking along with the person undergoing anaphylaxis – they may fail to read or misunderstand the directions, or even resort to trial and error.

Not coincidentally, one of the most frequently observed use errors with the EpiPen is upside-down injection into the user’s thumb.

Of course, this is only one example; a comprehensive use-related risk analysis for each potential user in each potential situation would be too detailed to outline in a blog post. But the important takeaway is that it’s paramount to demonstrate to the FDA that you understand the situational complexities of even the most common – and seemingly simple – use-related errors.

Next, we’ll look at how to design in support of controlling for use-related risks.

Mitigate identified use-related risks 

Once you have identified all the risks – critical and otherwise – associated with the use of your product, the next step toward a successful submission is controlling against those risks through design – and then testing whether your design successfully reduces the identified risks.

To examine an example of how this looks in practice, say you want to prevent inexperienced users from stabbing themselves in the thumb with the auto-injector needle when administering medicine to someone experiencing anaphylaxis. To achieve this, you might consider:

  • More clearly communicating which end has the needle by changing the color of the needle cover and/or the safety cap
  • Changing the shape of the device to direct a specific ergonomic grip, preventing users from placing their thumb over the needle end
  • Incorporating a “grip safety” feature on the side to encourage correct hand placement

Now say you select the first option. Guided by the inherent knowledge that “green means go,” you might choose to change the cap’s color to green. But now there’s another problem. “Go” is in this instance inexact. Does it represent the end to press so the needle goes into the skin? Or is it what’s pressed into the skin so that the medicine is administered?

While those issues may be solved with directional identifiers like arrows, they may still create other problems. Though green means “go” in some cultures, in others it’s associated with death. So while the color may have fixed one user groups’ needs, it’s introduced an issue for another.

Your next step? Continue the design journey and search for an alternate, location-independent solution, such as changing the device’s shape or incorporating additional safety features. You might even refer back to the ethnographic research that helped you originally identify your use-related risks to ensure you consider the most comprehensive set of solutions possible.

Show clinical benefits outweigh residual risks

A good rule of thumb in the development space is, “There’s no such thing as a perfect medical device.” A perfect medical device is so intuitive that it doesn’t require instructions. It’s never impacted by use errors. It neither breaks nor expires. In theory, it’s so intuitive and easy to use that patients know how and when to use it without hesitation – from the moment they first get their hands on it.

But in the real world, when people are burdened with completing a task, they run the risk of getting it wrong. And as medical devices are concerned, getting it wrong means delivering substandard medical care at best – and at worst, serious clinical harm.

To dive into this idea a bit deeper, let’s consider a typical “dial and dose” pen injector. 

A pen injector, as opposed to a single-use auto-injector, requires the user to select the dose before injecting. Seems simple, right? In reality, dialing (and injecting) the wrong dose is one of the most frequent use errors observed with pen injectors. And as long as the user is responsible for dialing the dose, there’s a potential use-related risk of dialing in the wrong dose.

Can manufacturers prevent that risk? Yes, of course. The risk of dialing the wrong dose is easily preventable by developing a single-use auto-injector, like the EpiPen. But such devices are by definition only usable once, bringing up issues of waste, disposability, and storage. 

Furthermore, single-use auto-injectors contain a fixed dosage. That means they’re only helpful for users who can benefit from that specific dosage, say the 0.15mg of epinephrine in an EpiPen. As such, an EpiPen isn’t the appropriate therapy for users who need less than 0.15mg of epinephrine. One potential solution? A “dial and dose” injector.

Again, while this is only one example, it demonstrates an instance when the clinical benefits of a “dial and dose” injector outweigh the residual risks of an auto-injector. Though there’s no perfect medical device, submitting a successful HFE package depends on evaluating a variety of situations like this, and continuing to ask questions – and seek answers – until your manufacturing process has balanced a product’s benefits and risks to the most reasonable degree possible.

Asking the right questions is critical to successful design

Whether you work at a 12-employee startup or a legacy manufacturing company with thousands of staff, working with the right human factors research partner is critical to your success. Bold Insight has a team of over 100 human factors and user experience practitioners ready to collaborate with manufacturers to bring products from concept to launch.

Whether you’re wondering what questions to ask or already taking steps to find the right answers, we’re here to work through the process with you.