Medical Device Classification

In vitro diagnostics (IVDs) are a subcategory of medical devices and rely on the medical device classiﬁcations. IVDs are considered medical devices even when they are paired with drugs as companion diagnostics (i.e., products which must be used to evaluate a patient prior to a drug being given).

Determining which class a product falls into depends on two factors: the level of risk it the information presents to the consumer and whether or not there are other products like it that have been previously approved. Although FDA has been blurring this decision-making process in recent years, it’s easiest to start with the basic deﬁnitions and then discuss the exceptions that have been made.

Class I Devices

Class I medical devices are products that FDA believes present a very low risk to the consumer and are substantially equivalent to other products already on the market. Most Class I products are exempt from FDA review. When a company produces a Class I medical device they must register their establishment and the product they intend to sell with FDA but most of the time further scientiﬁc review is not necessary.

Some Class I products may also be exempt from many of the Quality System Regulations (QSRs). Determining whether or not the product is exempt from QSR requirements is an important step when mapping regulatory strategy. Examples of Class I exempt IVD products include unassayed (qualitative, not quantitative) third party controls as long as they are not used for blood screening, general purpose laboratory reagents, and most Analyte Specific Reagents (ASRs). Third party controls and ASRs are exempt from scientiﬁc review but must be manufactured in a QSR compliant manner. General purpose reagents are exempt from scientiﬁc review as well but are also exempt from the majority of the QSR regulations.

Class II Devices

Class II medical devices are products that are substantially equivalent to previously approved products but, in the FDA’s view, require additional study and control. Class II products are subject to scientiﬁc review via marketing applications called 510(k)s or premarket notifications and must be manufactured in an environment that is QSR compliant. Part of the scientiﬁc review may include the need for a clinical trial.

Examples of Class II IVD products include HLA typing products, microarray instrumentation systems (as well as some microarrays, depending on intended use) and infectious disease genotyping assays.

FDA has created a special category for products that applies when they consider the risk to be Class II but where there is no previously cleared product, typically called predicate devices. This category is reviewed via a de novo 510(k) route. The de novo 510(k) was the pathway used by Affymetrix and Roche to obtain the first microarray/microarray instrumentation FDA clearances.

Class III Devices

Class III medical devices are products where there is not a substantially equivalent product to compare to or is a type of product that FDA considers too high of a risk to down-classify. For example, recent Class III products that have received FDA approval include a molecular assay for detection of mycobacterium turberculosis and an assay that provides analysis of breast lymph node tissue during or after surgery to determine whether additional lymph nodes need to be removed.