Device Classification and the Three Classes

Every device question begins with classification. It determines whether a product can be marketed after a notification, whether it needs an approval supported by clinical evidence, or whether it needs neither. It also determines the ongoing obligations that attach once the product ships. Classification is not a description of how sophisticated a device is; it is a statement about what controls are needed to make it reasonably safe.

Intended use drives the classification

The statute classifies devices by type, and a type is defined by intended use as much as by design. The same physical article marketed for two purposes can occupy two classes. This is why the labeling and the promotional claims are the first documents a regulator reads when asked what a product is.

Intended use is established by objective evidence rather than by what a company says it means. Labeling, advertising, statements by representatives, and the circumstances surrounding distribution all bear on it. A product sold with instructions describing a clinical purpose has that intended use whether or not the classification submission mentioned it, which is why marketing materials and classification files should be written by people who read each other's work.

Classification regulations are codified by medical specialty across Parts 862 through 892 of Title 21, covering areas from clinical chemistry to physical medicine. Each entry gives an identification of the device type, its class, and any applicable special controls or exemptions. A manufacturer identifies the entry matching its product, and where nothing matches, that absence is itself the answer to a different question addressed below.

Class I and general controls

A device is in class I where general controls are sufficient to provide reasonable assurance of its safety and effectiveness, or where there is insufficient information to make that determination but the device is not purported to be for a use in supporting or sustaining human life or of substantial importance in preventing impairment of human health, and does not present a potential unreasonable risk of illness or injury.

General controls are not trivial and they apply to all three classes. They include the prohibitions on adulteration and misbranding, establishment registration and device listing, records and reports, good manufacturing practice requirements, the authority to ban devices, and notification and repair, replacement or refund provisions. Many class I devices are exempt from premarket notification by regulation, which is the source of the common but inaccurate belief that class I means unregulated.

Class II and special controls

A device falls in class II where general controls by themselves are insufficient to provide reasonable assurance of safety and effectiveness and there is sufficient information to establish special controls that will provide that assurance. Special controls are whatever the agency determines is necessary, and the statute gives examples: performance standards, postmarket surveillance, patient registries, development and dissemination of guidelines, and recommendations.

The evidentiary standard behind every classification decision is the same. Reasonable assurance of safety means that valid scientific evidence supports a conclusion that the probable benefits to health from use outweigh any probable risks, and reasonable assurance of effectiveness means such evidence supports a conclusion that use will provide clinically significant results in a significant portion of the target population. Valid scientific evidence is defined to exclude isolated case reports, random experience, reports lacking scientific detail and unsubstantiated opinions.

Special controls appear in the classification regulation for the device type and in guidance documents identified there. For a manufacturer, they function as a specification list: meet the identified standard, provide the identified testing, include the identified labeling statements. Most class II devices reach the market through premarket notification, and conformity with the special controls is a substantial part of what that submission demonstrates.

Class III, and the routes that change a classification

Class III covers devices for which insufficient information exists to determine that general or special controls would provide reasonable assurance, and which are life-supporting or life-sustaining, of substantial importance in preventing impairment of human health, or present a potential unreasonable risk of illness or injury. These devices require premarket approval supported by valid scientific evidence, and the difference between that route and notification is set out in premarket notification compared with premarket approval.

Classification is not fixed. The statute permits reclassification on the agency's own initiative or on petition, based on new information, and devices have moved in both directions. Separately, the de novo route allows a sponsor whose device is automatically class III solely because no predicate exists to request classification into class I or class II on the basis that general or special controls provide reasonable assurance. A granted request creates a new classification regulation, which later devices of that type can then use as a predicate.

Whatever class results, the obligations that follow are continuous rather than one-time. Quality system requirements and inspections apply as described in manufacturing quality systems and inspections, reporting duties attach as set out in adverse event and malfunction reporting, and the claims that placed the device in its class are the same claims constrained by labeling content and change requirements.