By: Susan Lubejko PhD and Abigail Copeland PhD, Regulatory Affairs Specialists at Mittal Consulting

While it may seem surprising, medical devices with the same technological characteristics but different clinical applications sometimes receive different classification from FDA. It all comes back to a device’s benefit-risk framework. The phrase “benefit-risk framework” is often used in medical device regulation as the mechanism that FDA uses for device classification. Considering the benefit-risk of a medical device to determine its classification may seem straightforward in terms of technological characteristics, but the context of its intended use is also key to consider as there may be substantial differences in regulatory and evidentiary requirements.

An interesting case study illustrating this arises with recent De Novo authorizations from Neurovalens. Last month, Neurovalens’ De Novo clearance for Class II Modius Spero (DEN250013) expanded its non-invasive vestibular nerve stimulation (VeNS) device platform into the treatment of post-traumatic stress disorder (PTSD). This expansion builds upon a previous De Novo authorization of Neurovalens’ Class I Modius Lean (DEN240076), which utilizes the same technology for weight management. These authorizations provide a clear example of how a single device technology can fall into different risk-based device classifications depending on intended use, thus impacting regulatory, evidentiary, and commercialization requirements.

As noted, Modius Lean and Modius Spero use the same VeNS technology, suggesting that the devices present the same direct risk of physical harm to patients. However, FDA has classified Modius Lean as a Class I medical device (despite using longer durations of electrical stimulation) and Modius Spero as a Class II device, insinuating that FDA’s consideration of the direct physical risk associated with VeNS is minor, and that the differentiation likely comes from the relative amount of risk contributed by the indications. In PTSD, ineffective treatment may lead to worsening of anxiety or PTSD symptoms, while with a weight loss indication the risk of an ineffective therapy is considered to be lower. By directly comparing the two authorizations of the same technology from the same Sponsor, it is easy to see how the risk level of a device, even when the technology has been previously cleared, is highly influenced by the indication.

Further, from a testing analysis perspective, the clearance for Modius Lean demonstrates the relatively lower validation bar and threshold for potential benefit for medical devices that can successfully argue a low-risk designation. While it is uncommon for a Class I De Novo device to require clinical data, certain neurological devices do require use on humans to demonstrate their effect that can’t be captured in bench or animal testing. Interestingly, Neurovalens conducted a pivotal clinical study for Modius Lean which failed to meet its predefined primary endpoint of weight loss, while meeting secondary endpoints related to decreased visceral fat (Viirre et al. 2025). For Class II and III device sponsors, this result would be unacceptable to support a premarket submission; however, in the case of a Class I medical device like Modius Lean, FDA interprets this differently. During pre-market review, FDA considers the extent of the probable benefits of the intended use the of the device in relation to the probable risks. Neurovalens likely argued successfully that relatively lower benefit for weight loss was acceptable due to the low risk related to the technology itself, the weight loss indication, and the resulting Class I designation.

These case studies illustrate that thoroughly considering risk, both from a technological and intended use perspective, is key in determining device classification and thus regulatory and evidentiary requirements for successful market entry. To best communicate with FDA review teams on their premarket submissions, Sponsors should frame their justifications for device classification and testing using a holistic assessment of the relative benefits and risks of their devices.

What does FDA’s finalized Human Factors guidance mean for upcoming device submissions?

On May 29, 2026, FDA published its final guidance on Content of Human Factors Information in Medical Device Marketing Submissions. Sponsors should take note, as there are subtle changes in FDA requirements between the 2022 Draft of this document and this year’s final revision. This final version provides much more clarity on Human Factors requirements as well as implies a potentially lower burden for usability information for certain simple and widely used devices in premarket submissions starting on August 3rd.

Human factors (HF) validation, often called “usability”, evaluates how intended users interact with medical device interfaces in their use environment, ensuring that devices can be used safely and correctly. This guidance document provides a risk-based framework for Sponsors to determine HF content that should be included with their marketing submissions. FDA defines three HF Submission Categories with increasing documentation and validation needed for increasing use-related risk. To determine their HF Submission Category, Sponsors are directed to a flow chart that probes whether the device is an update to an existing device, whether the device has “critical tasks” (steps in the use workflow that could cause harm if done incorrectly), and whether there is a history of use with similar devices and interfaces. Category 1 and 2 devices need only high-level summaries of existing HF efforts and descriptions of users, environments and interfaces, whereas Category 3 devices require full risk analysis and usability testing information.

The most notable change between the 2022 draft guidance and this finalized one is a new node that has been added to the decision flowchart. Previously, all devices with identified critical tasks would be automatically assigned to HF Category 3 and required to produce testing documentation. The new decision point asks Sponsors to consider the question: “Should HF validation test data be submitted for my device?”. If a device has good justification that it is simple, risk control measures are adequate, and the interface has a robust use history with same the intended users, it can now fall into HF Category 2. If not, the device falls into HF Category 3. This change loosens HF documentation requirements for simple devices with documented use history, even if they have critical tasks. This potentially signals a new FDA posture on usability, after a period where full validation testing appeared to be required for most devices and testing specifics could only be discerned by direct discussions with FDA.

Changes to eSTAR templates for 510(k) and De Novo submissions also accompanied this final guidance. Previously, there was not a dedicated section in eSTAR for usability information, and its inclusion (or not) was relatively hidden. Now, on eSTAR 7.0 which takes effect on August 3rd, HF is a prominent section with specific required material based on the selected category. Although not required until August, Sponsors currently working on a submission that could extend into the fall should consider consulting the new guidance to ascertain their HF documentation burden. For some Sponsors, the documentation burden may actually be lower than expected – and for all Sponsors, FDA’s HF expectations have been made clearer.