It is not enough for medical devices to work correctly | Why the FDA emphasizes Human Factors [GeXPs26-0720JPN]
It is not that new tests are required for all products, but rather that changes in users, usage environments, and critical tasks must be explained.
Even if a medical device functions according to its specifications, it cannot be called a safe product if the user makes an operational error.
Similar buttons are lined up on the screen.
The meaning of the alarm is difficult to understand.
Connection parts can be inserted in reverse.
Important operations cannot be understood without reading the manual.
These problems do not arise from mechanical failure, but at the 'interface between humans and equipment'.
The final guidance on Human Factors published by the US FDA on May 28, 2026, organizes how much this interface should be explained when applying for medical device approval.
It may look difficult, but the core message is simple.
The FDA has not requested new user testing for all medical devices.
It is necessary to confirm how much the product's usage, users, usage environment, screens, buttons, and manuals have changed, and to explain whether past documentation is sufficient or if new actual-use validation is required.
■ What is Human Factors?
Human Factors is a concept for confirming whether people can actually use medical devices safely.
The scope is not limited to the device itself.
・Buttons
・Screens
・Alarms
・Sounds
・Connection parts
・Packaging
・Labels
・Instruction manuals
・Training
・Operating procedures
All of these are User Interfaces that connect people and equipment.
For example, if there is a possibility of misreading '10.0' and '100' on the screen for setting the infusion volume, it can lead to a serious accident even if the device is operating normally.
The FDA calls tasks that could lead to serious harm if performed incorrectly or not performed at all 'Critical Tasks'.
■ When moving from hospital use to home use, the conditions change even for the same device
The risks differ even with the same operation screen between devices used by professional medical staff in hospitals and devices used by patients or their families at home.
In a hospital, colleagues may be nearby, the user is trained, and the device can be used in a well-lit environment.
On the other hand, at home, situations occur such as using it alone at night, having limitations in vision or hand movement, being unable to hear the alarm well, or having received instructions only once.
Therefore, the following changes must be carefully confirmed.
・From medical staff use to patient use
・From hospital use to home use
・Changes in screen or button layout
・Changes in alarm sounds or displays
・Changes in packaging or labels
・Changes in manuals or training methods
・Addition of new connection parts or accessories
■ Three situations indicated by the FDA
The final guidance organizes the Human Factors information to be included in submissions into Categories 1, 2, and 3.
However, this is not a classification of medical devices into low, medium, or high risk.
To put it simply, these are the following three situations.
[Situation 1: No changes that affect the Human Factors evaluation]
This applies to changes to devices already permitted for sale in the U.S. where there are no changes to users, intended use, use environment, screens, buttons, instructions, training, etc., that would affect the Human Factors evaluation.
The company should concisely explain what is being compared and why it does not affect the Human Factors evaluation or Critical Tasks.
[Situation 2: Can provide a rationale for not submitting new validation test data]
This applies when no Critical Tasks are identified for a new device, when no new or affected Critical Tasks are identified for a modified device, or when it can be objectively explained that existing safety measures remain effective.
What is important here is that having past data does not automatically mean that testing is unnecessary.
Use past tests, Use-Related Risk Analysis (URRA), complaints, label comparisons, operating procedure comparisons, etc., to demonstrate 'why safety can be explained without submitting new validation test data.'
[Situation 3: Submit Human Factors Validation Test data]
This applies when, based on the FDA's decision framework, the submission of validation data is recommended due to complex user interfaces, known use error issues, significant design differences, new safety signals, increased severity of harm, or new users or use environments.
In this case, a Human Factors Validation Test, in which representative users perform Critical Tasks in a near-realistic environment, becomes important. However, specific changes do not automatically mean Category 3; decisions are made based on use-related risks and available evidence.
■ Do not discard existing materials, but 'reconnect' them
There is no need to interpret this guidance solely as a request to increase testing.
Rather, what is important for companies is to organize the materials they already have into a usable format.
For example, the following materials:
・Past user tests
・Design change records
・Use-Related Risk Analysis (URRA)
・Complaints
・Recalls and corrective actions
・Change history of instructions
・Comparison of screens and buttons
・Educational materials
・Change records from overseas factories
If a device is designed at a Japanese headquarters and manufactured in Vietnam, Thailand, or Malaysia, changes at overseas factories may affect operation feel, displays, connection parts, or packaging.
Even if they appear to be minor changes to the manufacturing department, they may be subject to Human Factors verification if they affect user operation.
■ 5 things to check now
Who are the actual users?
Consider physicians, nurses, technicians, patients, family members, caregivers, installation personnel, and maintenance personnel separately.
2. Where will it be used?
Lighting, noise, communication, and emergency response differ between hospitals, clinics, ambulances, homes, outdoors, and while in transit.
3. What operations are dangerous if performed incorrectly?
Identify critical tasks from settings, connections, infusions, confirmations, cleaning, replacements, alarm responses, etc.
4. Can past documentation be reused?
Compare the differences in products, users, usage environments, screens, and operating procedures.
5. Is a new validation test really necessary?
If the necessity is unclear and testing costs are high, there is a method to consult with the FDA via Pre-Submission before starting the test.
■ August 1, 2026 is not the "effective date of a new law"
The FDA's eSTAR was updated in June 2026 to reflect the content of this Human Factors guidance.
The FDA stated that both companies and the FDA need about 60 days of preparation time to incorporate the guidance into practice, and anticipates that applications received before August 1, 2026, may not contain all the newly recommended information.
However, this does not mean that a new law will go into effect on August 1.
FDA guidance is, in principle, not a regulation with legal binding force, but a document explaining the FDA's current thinking and review policy.
Nevertheless, for applications after August, being prepared to explain "why this documentation is sufficient" or "why new validation data is necessary" is important to reduce the risk of requests for additional information and review delays.
■ Summary
For medical devices, it is not enough for them to just work correctly.
It is necessary to design them so that users can operate them safely in the actual environment.
This latest FDA final guidance is not a system that adds testing to every product.
It is a framework for organizing whether existing evidence is sufficient or if new summative usability testing is required by reviewing changes in users, use environments, screens, buttons, instructions, training, and critical tasks.
For Japanese companies, the most important response is not to view Human Factors as a test to be performed just before submission, but as safety management that connects design, quality, manufacturing, labeling, training, complaints, and post-market information.
The starting point for judgment is not "is a new test required?"
It is about what has changed, which critical tasks are affected, and whether the effectiveness of risk management can be explained with existing evidence.
[Official Information]
・U.S. FDA, Content of Human Factors Information in Medical Device Marketing Submissions, Final Guidance, May 28, 2026
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/content-human-factors-information-medical-device-marketing-submissions
・U.S. FDA, Final Guidance PDF
https://www.fda.gov/media/163694/download
・U.S. FDA, eSTAR Program
https://www.fda.gov/medical-devices/how-study-and-market-your-device/estar-program
・U.S. FDA, Human Factors: Premarket Information – Device Design and Documentation Processes
https://www.fda.gov/medical-devices/human-factors-and-medical-devices/human-factors-premarket-information-device-design-and-documentation-processes
・U.S. FDA, Applying Human Factors and Usability Engineering to Medical Devices
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/applying-human-factors-and-usability-engineering-medical-devices
[Disclaimer]
This article is a general explanation based on publicly available information. For individual product FDA submissions, testing requirements, and legal judgments, please check product-specific guidance, applicable laws and regulations, and the results of consultations with the FDA.
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