On April 27, the Food and Drug Administration (FDA) released its promised draft guidance document, Multiple Function Device Products: Policy and Considerations, explaining how it will regulate multiple function devices that have at least one "device function" that is subject to FDA premarket review and at least one "other function" that is not. "Function" refers to each distinct purpose or intended use of the device.

For instance, software that stores, transfers and analyzes data can be said to have three purposes or functions, only one of which (analysis) likely would be regulated as a medical device. Each "other function" may not require premarket review either, because:

1. The function does not meet the definition of a device.
2. The function is a device function but is exempt from premarket submission.
3. The function may be a device function, but FDA has chosen not to enforce the regulations with respect to that function.

The draft guidance stems from the addition of Section 520(o) to the Food, Drug and Cosmetic Act by 21st Century Cures Act. Section 520(o) excludes from the definition of a medical device certain software functions (which FDA has addressed in previous guidance) and delineates the scope of FDA’s authority over multiple function devices (which is addressed in this guidance). Specifically, Section 520(o)(2) grants FDA the authority to assess the impact of a non-device software function on the function that is a device in a multiple function device, but prohibits FDA from directly regulating the non-device software itself.

Not surprisingly, and consistent with its overall risk-based approach to digital health and low risk devices, FDA clarifies in the guidance its intention to apply the same principle found in the Cures Act not just to multiple function devices with non-device software, but to all multiple function products. Further, FDA will not directly review any "other function" that might be a device but that is subject to FDA’s enforcement discretion "merely because it is part of a multiple function device product." In other words, FDA will review the impact that enforcement discretion functions have on the safety and effectiveness of the "device function-under-review", but will directly review only the device function(s) for which clearance or approval is sought.

The guidance goes on to discuss questions and considerations for manufacturers when making impact assessments for multiple function devices regarding whether and how the "other" functions may affect the "device" function, and what FDA expects in premarket submissions when they do. Where the "other function" impacts the device function-under-review such that the combination increases risk or negatively affects performance of the device function, (this could occur, for instance, where all of the functions compete for the same computational resources or where the device function depends on the accuracy of data supplied by the other functions), FDA expects submissions to include, among other things:

• A description of the impact of the other functions on the device function-under-review
• Detailed explanations regarding the architecture and design of the device, including how the other functions interact with or impact the device function-under-review
• Risk Analysis that includes a risk based assessment of the impact of the other functions and any risk mitigations.
• Documentation of requirements and specifications, including any expected relationship, reliance or interoperability between the functions

If the other functions positively impact the device function-under-review, the submitter may choose to include these elements in the submission to assist FDA's assessment of the device function. However, if the other functions do not impact the device function-under-review, FDA does not intend to assess the other functions and will expressly include a statement to that effect in the 510(k) Summary, PMA Summary of Safety and Effectiveness Data, De Novo Summary, or HDE Summary of Safety and Probable Benefit. This means that FDA’s decision to clear or approve a device applies only to the function that was reviewed. FDA likens this model to a 510(k) exempt accessory device (a guidewire) that is contained in a PMA submission for a primary device (an intragastric balloon).

The guidance also cautions that adverse event reports should be submitted by manufacturers of multiple function devices if information reasonably suggests that a death or serious injury may have been caused by the regulated function, and provides examples of multiple function device assessments, which manufacturers should review carefully.

Although FDA's rapid pace in the digital health space is welcome, it often raises a host of questions that remain unanswered and well only may be answered as the guidance is implemented. For instance, as described above, the manufacturer is tasked with determining whether a function is an "other" function or a device function and whether the "other" might have a positive or negative impact on the device function. Whether and under what circumstances FDA might assess the accuracy of such determinations—and seek to punish a manufacturer's incorrect one—is unclear.

Similarly, whether manufacturers can rely upon FDA's proposed statement that the other functions "are not subject to FDA premarket review" as confirmation that such function will not be regulated also is uncertain—particularly given the guidance's caution that, even when finalized, it "does not establish any rights for any person and is not binding on FDA or the public."

Outside the regulatory space, another implication of the draft guidance might be how FDA’s explicit exclusion of the "other" function from the clearance or approval will affect an assertion of the federal preemption defense in product liability litigation, especially where the impact of the other function has been assessed. This question seems likely to be resolved by the courts.

As we suggested here, the efforts of Congress and FDA to potentially narrow or "lighten" the regulatory load on manufacturers to encourage innovation does not necessarily correspondingly reduce uncertainty for how a manufacturer is to proceed in light of this changing landscape.