How to Prepare for an FDA Human Factors Validation Test

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

Starting this activity too early can be costly. For example, an incomplete use-related risk analysis or last-minute design change can lead to pushback and costly delays during an FDA submission.

So, how do you know when your medical device is ready for human factors validation testing?

Below we describe some of the key areas to have in place when preparing your study.

Ensure production equivalence

One of the first questions to ask is simple:

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

For a human factors validation test, 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 on the validity of the human factors validation test results.

Develop a robust use-related risk analysis

The device’s Use-Related Risk Analysis (URRA) is one of the most important inputs to a human factors 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 medical device.

Most importantly, the use-related risk analysis helps identify your critical tasks (i.e., the user tasks that require particular attention during the human factors validation test because a use error or failure to perform the task could result in serious harm). The critical tasks identified in your use-related risk analysis should feed directly into your human factors validation protocol and evaluation activities that participants will perform.

Make sure every critical task can be traced from the use-related risk analysis to the human factors validation test protocol. By doing so, you provide a clear link between the identified use-related risks and the validation evidence supporting your final human factors documentation.

Identify the device user groups

A common question we often receive from medical device companies planning their human factors validation test 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 neccesarily 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 human factors validation budget, recruitment timeline, and overall study duration.

Consider recruitment lead time

Participant recruitment can easily become the bottleneck of a human factors 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 user groups.

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

Simulate a representative test environment

The test environment in a human factors validation test should representatively simulate the use conditions in which users will interact with the medical device during real-world use. 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 might need to simulate a representative home environment. In essence, consider the factors that could realistically influence user performance, including lighting, noise, workspace, interruptions, medical equipment, communication between users, and the physical position of the device, users, and patients.

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

Decide whether training should be included

Do you intend to provide formal training to end users when your device reaches the market? If so, the human factors validation test should generally represent that intended training approach. An appropriate training decay period may also be needed between the training and test session.

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

In short, the human factors validation study should represent the real-world approach, not teach participants how to pass the study.

Develop the HF validation test protocol

Once your device, labeling, use-related risk analysis, user groups, and potential training approach are defined, the human factors validation test protocol can be developed.

A strong protocol connects realistic use scenarios directly to the critical tasks identified through your use-related risk analysis. When developing prompts for evaluation activities that participants will perform be mindful with the 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 device specific interactions.

Maintain a realistic timeline

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

Consider the following timeline as a general planning estimate:

HF validation activity	Approximate 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 need to happen sequentially. Recruitment, for example, may begin while the protocol is being finalized. For a relatively straightforward HF Validation study, you might therefore plan for approximately 7–10 weeks from protocol development through completion of the HF validation test report. However, this is mainly dependent on participant recruitment, review cycles, and study complexity.

More complex programs can take longer. The duration of a study involving 15 participants from one user group involving 60-minute test sessions is very different from a study involving 45 participants across 2-hour sessions from three user groups.

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

Decide whether FDA feedback is needed

Not every medical device manufacturer needs FDA feedback on its human factors 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 misalignment with your validation approach after conducting the study can be considerably more expensive.

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Sources:

View FDA’s 2026 Human Factors Guidance

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