FDA Human Factors Validation Testing: How to Prepare Your Medical Device

Preparing for an FDA human factors (HF) validation test requires careful planning to ensure your device, labeling, use-related risk analysis, and study design are ready for validation.

Starting this activity too early can be costly. A design change, or an incomplete use-related risk analysis discovered during or after the HF validation test can lead to additional testing and costly delays to an FDA submission.

So, how do you know when your medical device is ready for HF validation?

Here are the key areas to have in place before starting your study.

1. Ensure production equivalence

One of the first questions to ask is simple:

Is the device we are testing representative of the device we intend to commercialize?

For an FDA HF validation study, participants should interact with a medical device that adequately represents the final user interface, including both the device and its labeling. Without a production-equivalent product, the study results may not accurately reflect real-world use, potentially leading to questions or pushback from the FDA.

2. Robust use-related risk analysis

The device’s Use-Related Risk Analysis (URRA) is one of the most important inputs to an HF validation test. Before moving into validation, you should ensure that a robust URRA has been developed that thoroughly evaluates all potential use-related risks associated with the device.

Most importantly, the URRA helps identify your critical tasks (i.e., the user tasks that require particular attention during validation because a use error or failure to perform the task correctly could result in serious harm). The critical tasks identified through the URRA should feed directly into your HF validation protocol and test scenarios.

Tip: Make sure every critical task can be traced from the URRA to the HF validation study. This provides a clear link between the identified use-related risks and the validation evidence supporting your final HF documentation.

3. Identify the device user groups

A common question we often receive is:

How many participants do I need for an FDA human factors validation study?

To ensure compliance with FDA’s guidance on human factors and usability engineering, manufacturers should plan for at least 15 participants per distinct user group. In other words, if your device has one user group, your study should involve at least 15 participants from that user group.

Different job titles doesn’t automatically mean different user groups. The key question is whether differences in device responsibilities, experience, training, capabilities, or other types of interaction with the device could affect how safely and effectively the product is used.

Identifying your user groups early is important because it can dramatically affect your HF validation budget, recruitment timeline, and overall study duration.

4. Consider recruitment lead time

Participant recruitment can easily become the bottleneck of an HF validation study. As a general planning assumption, we often take into account approximately three weeks for participant recruitment, although recruitment can take longer for specialized populations or multiple intended user groups.

Recruitment can often run partly in parallel with the HF validation protocol development, provided the user groups, screening criteria, study location, and anticipated study dates are sufficiently established.

5. Simulate a representative test environment

An HF validation study test environment should simulate the conditions in which users will actually interact with the medical device. For a hospital product, that might mean recreating an operating room (OR) environment, intensive care unit (ICU), or patient room.

For a home-use medical device, the study may instead need a representative home environment. Think about the factors that could realistically influence user performance, including lighting, noise, workspace, interruptions, personal protective equipment, other medical equipment, communication between users, and the physical position of the user and patient.

The goal should not be to reproduce every detail of a real clinical environment but the conditions that matter to safe and effective use.

6. Decide whether training should be included

Will users receive formal training when your device reaches the market? If so, the HF validation study should generally represent that intended training approach. An appropriate training decay period may also be needed between training and validation testing.

On the other hand, if users are expected to take the device out of its packaging and use it based on the supplied labeling, providing extensive study-specific training could create an unrealistically favorable test condition.

The HF validation study should represent the real-world approach, not teach participants how to pass the study.

7. Develop the HF validation test protocol

Once your device, labeling, URRA, user groups, and training approach are ready, the HF validation test protocol can be developed.

A strong protocol connects realistic use scenarios directly to the critical tasks identified through your URRA. Be careful with scenario wording. Participants should be given enough context to behave realistically without being told how to complete the task correctly. If your scenario effectively gives away the correct action, you may no longer be meaningfully evaluating that interaction.

8. Develop a realistic timeline

A realistic timeline is important when working backward from a planned FDA submission date.

As a general planning estimate:

HF validation activity	Typical timeline
HF validation protocol development	~3 weeks
Participant recruitment	~3 weeks
HF validation study conduct	~1–2 weeks
HF validation test report	~3 weeks

Fortunately, these activities don’t always happen sequentially. Recruitment, for example, may begin while the protocol is being finalized. For a relatively straightforward study, you might therefore plan for approximately 7–10 weeks from protocol development through completion of the HF validation report, depending on recruitment, review cycles, facility availability, and study complexity.

More complex programs can take longer. A study involving 15 participants from one user group with 60-minute sessions is very different from a study involving 45 participants across three user groups, specialist healthcare professionals, two-hour sessions, training, and specialized clinical equipment.

Your timeline should also account for internal reviews, protocol revisions, participant scheduling, potential IRB or ethics review where applicable, and any planned FDA interaction.

9. Decide whether FDA feedback is needed

Not every medical device manufacturer needs FDA feedback on its HF validation protocol before testing. However, obtaining feedback before validation can be valuable for devices with complex or novel human factors considerations.

This needs to be planned well in advance. Waiting for FDA feedback can add significant time to your development schedule, but identifying a fundamental disagreement with your validation approach after conducting the study can be considerably more expensive.

Need expert support?

Human Factors Insight supports medical device manufacturers throughout the human factors engineering process, including the development of use specifications, task analyses, Use-Related Risk Analyses (URRAs), formative usability testing, HF validation protocol development, participant recruitment, study execution, HF validation reporting, and Human Factors Engineering documentation for FDA submissions.

Whether you are preparing for validation or still determining whether your device is ready, we can help identify the remaining gaps and develop a practical path toward your HF validation study.

Fill out the contact form below and we’ll be in touch shortly.

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Sources:

View FDA’s August 2026 Human Factors Guidance

View FDA’s current HFE/UE report structure and submission guidance