FDA Device Guidance: Medical Device Accessories: Defining Accessories and Classification Pathway for New Accessory Types

The Food and Drug Administration set an ambitious guidance schedule for itself this year. On January 20, the Center for Devices and Radiological Health (CDRH) published two guidances—one on medical device accessories and the other on low risk or “general wellness” devices. This article walks through the accessory guidance, in which FDA clarifies that medical device accessories will not automatically take on the classification (Class I, II, or III) of the “parent device.” The agency will regulate based on the risks that individual accessories present when used with their parent device, and not based on the risks of the parent device.

As a background, in the U.S., medical devices are divided into three categories.

• Class 1 (low risk): includes, for example, examination gloves, elastic bandages, tongue depressors, hand-held surgical instruments. Most do not require FDA approval, but manufacturers must register the device and company on FDA’s website. The length of the approval process tends to be less than one month.
• Class 2 (medium risk): includes products that could harm a patient if they malfunction or are used improperly. Nearly all must go through a 510(k) pre-market notification submission where new products must be compared to an already cleared predicate device. FDA reviews 510(k) applications within 90 days, but also may drag on up to a year.
• Class 3 (high risk): includes products that could seriously injure or kill a patient if they malfunction or are used improperly. These devices must go through a rigorous pre-market approval (PMA) process that requires clinical trials and may take up to three years to obtain FDA approval.

What are medical device accessories, and in what Class do they belong?

In its guidance, FDA states that an accessory device is one that is intended for use with one or more “parent devices,” or that is intended to support, supplement, and/or augment the performance of one or more parent devices. FDA states that they will determine whether an article is intended for use with a parent device by the “labeling and promotional materials for the potential accessory device (rather than by the labeling and promotional materials for the parent device).”

For example, a parent device might be an automated external defibrillator. A rechargeable battery would be considered an accessory that supports the defibrillator’s intended use. FDA also states that a device can supplement the performance of a parent device as in the case of a pulse oximeter supplementing a multi-parameter monitor to display oxygen saturation. The pulse oximeter does not change its parent device’s intended use, which FDA states is to record and display multiple physiological parameters. A device may also augment a parent’s performance by enabling the device to perform its intended use more safely or effectively. For example, “a guidewire augments the performance of a bone-cutting instrument by increasing precision of the parent device and reducing the risk to the patient.”

FDA clarifies that these device accessories would not automatically take on the classification of their parent devices. “For example,” notes the agency, “if a parent device warrants regulation as a Class II device but an accessory to the parent device presents lower risks, we would regulate the accessory as a Class I rather than a Class II device.”

“FDA intends to determine the risk of accessories and the controls necessary to provide a reasonable assurance of their safety and effectiveness according to their intended use in the same manner that is used to determine such for devices that are not accessories,” FDA states. “Because accessories are intended to be used with and to support, supplement, and/or augment one or more parent devices, FDA will determine the risks of accessories when used, as intended, with the parent device type” (emphasis added). 

The agency clarifies that determining the risks of accessories according to their use with parent devices does not mean that all risks of a parent device are imputed to the accessory–the risk profile of an accessory can “differ significantly” from that of the parent device, warranting differences in regulatory classification. “In determining the classification of an accessory, FDA will evaluate the risks imposed by the accessory’s impact on the parent device and any unique risks of the accessory independent of its parent device,” states FDA. “As with the classification of any other device, the types of regulatory controls necessary to control the risks will determine the regulatory class for accessories.”

FDA offered an important clarifications regarding computers and iPhones: 

It is important to note that articles that do not meet the definition of an accessory will not be treated as accessories simply because they may be used in
conjunction with a device. For example, a mobile phone that is used as a
general platform for applications that include mobile medical applications that
are medical devices, or an off-the-shelf computer monitor used to display
medical data would not be considered accessories unless they are intended for
use with such devices.

FDA’s guidance also stressed that companies should pursue a de novo classification pathway for many device accessories. This process provides a pathway to Class I or Class II classification for accessories for which general controls or general and special controls provide a reasonable assurance of safety and effectiveness, but for which there are no legally marketed predicate device.

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Click here to view Medical Device Accessories: Defining Accessories and Classification Pathway for New Accessory Types. Comments are due by April 20.