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Determining When It’s Possible to Forgo HF Validation Testing

HF validation testing may not be necessary for medical and drug delivery devices. Learn from Emergo by UL's insights on navigating FDA regulations and developing sufficient justifications.

Validation testing reports

May 6, 2024

By Andrea Dwyer and Emilee Stanczyk

We at Emergo by UL firmly believe that Human Factors (HF) validation testing is an important part of the medical and drug delivery device development process. However, in some nuanced situations, it might be acceptable to forgo HF validation testing. In this article, we share our experience navigating the task of determining whether an HF validation test is necessary for a product and developing sufficient documentation accordingly.

Is HF Validation Testing Always Necessary?

There’s no doubt HF validation testing is a major milestone in a product development effort and a critical activity in many cases. To successfully plan and conduct an HF validation test, it takes:

  • Substantial people resources, often internal and external team members working together.
  • A significant monetary investment, especially if you find yourself with a larger sample size, expensive participants, or a tough recruit requiring extensive travel.
  • Supplies, including ensuring your production-equivalent product, labeling, and training are ready to go.

The time, expense, and effort required to conduct an HF validation test is enough to ask the question: Is it always necessary to conduct HF validation testing? However, wanting to avoid spending the time, money, or effort is not sufficient justification for not performing an HF validation test. Ultimately, the goal is to validate that the product’s user interface is safe and effective and that the mitigations you have in place are effective at controlling the risk. When discussing forgoing HF validation testing, we are not advising you to skip HF work. We are advising you to perform the correct work to demonstrate your product is safe and effective and that the mitigations you have in place control the risk.

FDA’s openness to justifications for drug delivery devices

FDA’s Center for Drug Evaluation and Research (CDER) has demonstrated an openness to justifications that in some cases no HF validation test is needed. As far back as CDER’s draft HFE guidance from 2016, CDER provided certain example scenarios where they would not expect an HF validation test, such as for a familiar prefilled syringe used by HCPs in an acute care setting. Further, in a workshop setting, CDER has reiterated that sponsors can rely on certain existing data to mitigate the need for an HF validation test. In both cases, FDA asks for a justification. We have also seen this sentiment routinely reiterated in direct feedback to sponsors.

FDA’s openness to justifications for medical devices

FDA’s Center for Device and Radiological Health (CDRH), has provided very relevant information related to justifying forgoing HF validation testing in the December 2022 guidance, Content of Human Factors Information in Medical Device Marketing Submissions. In this guidance, FDA defines three device categories based on whether the device is new or a modification and whether there are critical tasks. Submission Categories 1 and 2 do not require that an HF validation test be submitted for the product. Take for example Submission Category 2, which is when there are no critical tasks for new devices or no changes impacting critical tasks in the modified device. Again, the guidance tells us to provide a rationale and specifically does not check off HF validation testing in the recommended minimum human factors information provided.

Criteria for deciding when HF validation testing is needed

To determine the situations when HF validation testing is needed, or conversely, when a justification for forgoing HF validation testing is likely to be accepted, there are several questions you should ask yourself:

  • Is this product new? Or is it a modification to an existing product?
  • Are there critical tasks / unique risks? Or is there a low-risk profile?
  • Is this product novel? Or is it similar to an existing product’s user interface?
  • Is the device different from what users are familiar with? Or is the design commonly used and well-understood?
  • Is the procedure unusual? Or is it routine?
  • Is your product used by laypersons / outside the healthcare environment? Or only by healthcare professionals?
  • Do you have sufficient existing human factors-related data to assert that your product is safe and effective?

HF validation test likely necessary

Potential opportunity for justification

New device

Modification to an existing device

Critical tasks / unique risks

No critical tasks / low risk

Novel user interface

Minimal differences to comparator

Unfamiliar device design

Device design commonly used

Unusual procedure

Routine procedure

Layperson users

Healthcare professionals only

Lack of existing data

Sufficient existing data


If your answers generally fall on the left side of this table, plan to conduct and submit the results of an HF validation test. If your answers mostly fall on the right, you might have a good opportunity to justify forgoing an HF validation test.

Avoid attempting to rationalize forgoing HF validation testing for reasons such as not enough budget or time, no HF work for prior product, or worry that the results will not be favorable. These reasons will not be accepted.

Just because you might be able to forgo an HF validation test does not mean you can skip all HF work. In fact, you need to perform certain HF activities, such as conducting a use-related risk analysis, before you can decide whether you would be able make the justification. Think of it as performing a comprehensive design process involving HF work, but that you are replacing submitting validation test data with a justification. Contact our Emergo by UL Human Factors team for support on developing or reviewing your justification.

Andrea Dwyer is an Associate Research Director and Emilee Stanczyk is a Managing Human Factors Specialist at Emergo by UL.


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