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Developing a Strong Justification to Forgo Human Factors Validation Testing

Emergo by UL human factors specialists share tips for building a strong justification for forgoing HF validation testing.

Justifications for skipping human factors validation testing of medical devices

May 30, 2024

By Emilee Stanczyk and Andrea Dwyer 

In a prior article, we discussed when it is possible to forgo Human Factors (HF) validation testing. In this article, we will explain how to best craft your justification to increase the chance of acceptance by regulators. 

Core elements of a justification to forgo HF validation testing 

There are several core elements that your justification should include.  

  • The most important element will be a strong, fore-fronted conclusion. This conclusion should definitively assert and provide evidence that your product is safe and effective, drawing from other elements of your justification, discussed below. 

  • Your justification should include a detailed description of your device’s user interface, including any hardware, software, labeling and training, along with its intended use, users and use environments. 

  • Another very important element of your justification are items related to risk, such as a known problems analysis, comprehensive use-related risk analysis and a list of critical tasks.  

  • Finally, if there are similar existing products – whether predecessors or competitor products – your justification should include a comparative analysis. 

Justification for forgoing HF validation testing of medical devices

If these elements seem familiar, that is because they resemble an HFE report, without the HF validation testing, of course. Although you are trying to justify forgoing HF validation testing, that does not mean you can forgo other HF activities. Demonstrating that you have performed the necessary HF work and using the results of that work to reason your case is the best way to frame your justification. 

Additional elements to strengthen justifications 

In addition to these core elements, there might be other arguments you can use to strengthen your case, including: 

  • Prior usability testing. If you have usability test data that supports the validation claim in your justification, that data should be added. This data could include summative testing conducted outside of the US, prior formative testing that evaluated critical tasks identified in your use-related risk analysis or even clinical trials that captured usability data. If your product has a previous model that underwent HF validation testing, that data can complement your validation claim, especially if it is paired with a comparative analysis. 

  • On-market evidence. On-market evidence can support your validation claim. This could be data from post-market surveillance, on-market performance in other countries or evidence from predecessor devices. These data paired with your use-related risk analysis provide evidence that demonstrates the mitigations in place for your new product are indeed effective at mitigating risk. 

  • Familiarity. If a product has common use steps or design mitigations and is used in a way that is familiar to the intended users (for example, a routine injection for a healthcare provider), then you should use that familiarity in your justification. A more detailed comparative or threshold analysis of the product’s physical design, its labeling, and use-related risks is a great way to demonstrate this familiarity. 

  • Low use-related risk level. Our final element relates to a product’s use-related risk level. There are multiple ways you can demonstrate that the use-related risk level is low, and therefore does not warrant HF validation testing. You might conclude that there are no critical tasks, the risks have been inherently designed out or that there are no profound, unique risks. If there are predecessors, you can also compare the two use-related risk analyses to demonstrate that there are no new critical tasks. 

Examples of building a compelling justification 

For a vial kit used by healthcare professionals to administer drug, the elements of the justification should include a strong conclusion, device description, and intended use, users and use environment. Consider also including a comprehensive risk analysis and comparative analysis to a similar product and to strengthen your justification with familiarity claims. 

As another example, consider a medical device used by laypeople at home that is very similar to a prior version of the device from the same manufacturer. The justification should include the conclusion and core elements, a comparative analysis to the similar prior model of the device and data related to on-market evidence and prior usability testing. The comparative analysis should also provide a justification as to why each difference does not compromise the use-safety of the new device (if accurate). Identified differences related to critical tasks that do not warrant HF validation testing might be either improvements from a usability perspective or technical changes not impacting use of the device.  

The likelihood of a regulator accepting a justification to forgo HF validation testing depends on identifying when it might be possible to forgo HF validation testing and crafting a strong justification. To build a strong case, include the core elements and relevant supplemental elements in your justification. Contact our Emergo by UL Human Factors team for support on developing or reviewing your justification. 

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


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